MULTIPLE FLUID LINE MEDICAL TREATMENT SYSTEMS, METHODS, AND APPARATUS - Patent application

Abstract

To provide a volumetric standard cassette or cycler for calibration of a cassette based pumping system.SOLUTION: A volumetric standard cassette for calibration of a cassette based pumping system includes a rigid body configured for a sealing attached inside the cassette based pumping system. The rigid body includes: a center body; and some solid pump chamber regions each having a predefined shape defining a known volume of the pump chamber region. The rigid body includes neither flow path nor orifice.SELECTED DRAWING: Figure 66

Description

[Background technology]

[0001] Peritoneal dialysis (PD) involves the periodic infusion of a sterile aqueous solution (called peritoneal dialysis fluid or dialysate) into the patient's peritoneal cavity. Diffusion and osmosis exchanges occur across the autologous membrane between the solution and the bloodstream. These exchanges carry waste products into the dialysate, which is normally excreted by the kidneys. The waste products typically consist of solutes such as sodium and chloride ions, as well as other compounds normally excreted through the kidneys, such as urea, creatinine, and water. The diffusion of water across the peritoneal membrane during dialysis is called ultrafiltration.

[0002] Conventional peritoneal dialysis fluid contains a sufficient concentration of glucose to generate the osmotic pressure necessary to remove water from the patient through ultrafiltration.

[0003] Continuous ambulatory peritoneal dialysis (CAPD) is a common form of PD. Patients perform CAPD manually approximately four times per day. During the drain / fill procedure for CAPD, patients first drain used peritoneal dialysis fluid from their peritoneal cavity and then infuse fresh peritoneal dialysis fluid into their peritoneal cavity. This drain and fill procedure typically takes approximately one hour.

[0004] Automated peritoneal dialysis (APD) is another form of PD. APD uses a machine called a cycler to automatically infuse, dwell, and drain peritoneal dialysis fluid into the patient's peritoneal cavity. APD is particularly attractive to PD patients because it can be performed overnight while the patient is asleep. This eliminates the need for patients to perform CAPD daily during awake and working hours.

[0005] An APD procedure typically lasts several hours. It often begins with an initial drain phase, which empties the spent dialysate from the peritoneal cavity. The APD procedure then continues through successive fill, dwell, and drain phases. Each fill / dwell / drain step is called a cycle.

[0006] During the fill phase, the cycler delivers a predetermined amount of fresh, warmed dialysate into the patient's peritoneal cavity. The dialysate remains (or "dwells") in the peritoneal cavity for a period of time, referred to as the dwell phase. During the drain phase, the cycler removes spent dialysate from the peritoneal cavity.

[0007] The number of fill / dwell / drain cycles required during a given APD session is determined by the total volume of dialysate prescribed for the patient's APD regimen and is either entered as part of the treatment prescription or calculated by the cycler.

[0008] APD can be and is performed in a variety of ways.

[0009] Continuous ambulatory peritoneal dialysis (CCPD) is one commonly used APD modality. During each fill / dwell / drain phase of CCPD, a cycler infuses a prescribed volume of dialysate. After a prescribed dwell period, the cycler completely drains this fluid volume from the patient, leaving the peritoneal cavity empty or "dry." CCPD typically employs four to eight fill / dwell / drain cycles to achieve the prescribed treatment volume.

[0010] After the last prescribed fill / dwell / drain cycle in CCPD, the cycler infuses a final fill volume. The final fill volume remains in the patient's body for an extended period of time. It is drained at the start of the next CCPD session in the evening or during a daytime exchange. The final fill volume may contain a different concentration of glucose than the fill volumes of successive CCPD fill / dwell / drain fill cycles provided by the cycler.

[0011] Intermittent peritoneal dialysis (IPD) is another APD modality. IPD is typically used in emergencies, when patients are suddenly placed on dialysis treatment. IPD can also be used when patients require PD, but cannot assume the responsibilities of CAPD or perform it at home.

[0012] Like CCPD, IPD involves a series of fill / dwell / drain cycles. Unlike CCPD, IPD does not include a final fill stage. In IPD, the patient's peritoneal cavity remains empty of dialysate (or "dry") between APD treatment sessions.

[0013] Tidal peritoneal dialysis (TPD) is another APD modality. Like CCPD, TPD involves a series of fill / dwell / drain cycles. Unlike CCPD, TPD does not completely drain dialysate from the peritoneal cavity during each drain phase. Instead, TPD establishes a basal volume during the first fill phase and drains only a portion of this volume during the first drain phase. Subsequent fill / dwell / drain cycles infuse the basal volume plus an exchange volume, which is then drained. The final drain phase removes all dialysate from the peritoneal cavity.

[0014] There are variations of TPD that involve cycles in which the patient is completely drained and infused with a new full basal volume of dialysate.

[0015] A TPD may include a final fill cycle, like a CCPD, or alternatively, a TPD may avoid a final fill cycle, like an IPD.

[0016] APD offers flexibility and improved quality of life for those requiring dialysis. APD can relieve patients from the fatigue and inconvenience that the daily practice of CAPD presents for some. APD can return patients' waking and working hours without the need for dialysate exchanges. Summary of the Invention

[0017] An embodiment of the present disclosure provides a volumetric measurement standard set or cycler substantially as shown and described herein.

[0018] According to another embodiment of the present disclosure, a volumetric measurement standard set for calibration of a cassette-based pumping system may include a rigid body configured to seal within the cassette-based pumping system. The rigid body may have a central body and multiple solid pumping chamber regions, each having a predefined shape that defines a known volume of the pumping chamber region. The rigid body may be devoid of flow channels and orifices.

[0019] In some embodiments, the volumetric measurement standard set can be metal. In some embodiments, the volumetric measurement standard set can be machined. In some embodiments, the volumetric measurement standard set can be made from a list of materials consisting of aluminum, steel, and plastic. In some embodiments, the volumetric measurement standard set can be constructed via a material additive process. In some embodiments, the central body can have a thickness equivalent to at least half the thickness of the thickest part of the rigid body. In some embodiments, the central body can have a thickness equivalent to at least 60% of the thickness of the thickest part of the rigid body. In some embodiments, the central body can have a thickness equivalent to between one-half and three-quarters the thickness of the thickest part of the rigid body. In some embodiments, the volumetric measurement standard cassette does not include a cassette sheet.

[0020] According to another embodiment of the present disclosure, a volumetric standard cassette for calibrating a cassette-based pump system may include a central body that may be completely solid and may include a first surface and an opposing second surface. The volumetric standard cassette may further include several walls extending from at least the first surface of the central body, including a peripheral wall located at the periphery of the central body and several interior walls. The volumetric standard cassette may further include several solid pump chamber regions, each having a predefined shape that defines a known volume of the pump chamber region. The volumetric standard cassette may not be capable of pumping liquid.

[0021] In some embodiments, the sheet may not be bonded to any number of the walls of the volumetric standard cassette. In some embodiments, the first surface of the central body may not be covered by the cassette sheet and may include the pump chamber area. In some embodiments, both the first surface and the opposite surface of the central body may not be covered by the cassette sheet. In some embodiments, the volumetric standard set may be made from a list of processes consisting of material additive processes, machining, and molding. In some embodiments, the volumetric standard set may be made from a list of materials consisting of aluminum, steel, and plastic. In some embodiments, the opposite surface of the volumetric standard cassette may be flat. In some embodiments, the first surface of the volumetric standard cassette may include several protrusions that may be surrounded by the inner wall. In some embodiments, the wall may be draft-free.

[0022] According to another embodiment of the present disclosure, a cassette analog of a disposable pump cassette for calibrating a cassette-based pump system may include a central body having a first surface and an opposing second surface. The cassette analog may further include several sealing ribs on at least the first surface. The cassette analog may further include a first pump chamber region and a second pump chamber region. Each of the first and second pump chamber regions may have a defined, dimensionally stable shape that represents a selected fill volume of the corresponding pump chamber in the disposable pump cassette. The first surface and the opposing surface may be open or may lack an overlying cassette sheet. The cassette analog may be incapable of pumping liquid.

[0023] In some embodiments, the cassette analog may be formed of metal. In some embodiments, the central body may be completely solid. In some embodiments, the central body may lack any passages. In some embodiments, the selected fill volume may be the full pump chamber volume of the corresponding pump chamber in the disposable pump cassette. In some embodiments, the selected fill volume may be the empty pump chamber volume of the corresponding pump chamber in the disposable pump cassette. In some embodiments, the selected fill volume may be an intermediate volume between the full pump chamber volume and the empty pump chamber volume of the corresponding pump chamber in the disposable pump cassette. In some embodiments, the opposite surface of the volumetric standard cassette may be flat. In some embodiments, the first surface of the volumetric standard cassette may include several protrusions surrounded by sealing ribs. The number of protrusions may be positioned corresponding to the number of valve seats in the disposable pump cassette. In some embodiments, the cassette analog may lack ports, spikes, and attached fluid lines.

[0024] According to another embodiment of the present disclosure, a method for calibrating a cassette-based pump system may include sequentially installing several volumetric calibration cassettes in the cassette-based pump system. Each of the number of volumetric calibration cassettes may include a pump chamber region having a known volume. The method may further include measuring the known volume of the pump chamber region in each volumetric calibration cassette using the cassette-based pump system. The method may further include generating a calibration curve for volume measurements performed with the cassette-based pump system based at least in part on the known volumes for each of the number of volumetric calibration cassettes and the corresponding measured volume of the pump chamber region for each volumetric calibration cassette.

[0025] In some embodiments, measuring the known volume of the pump chamber region in each volume calibration cassette may include taking multiple measurements of the known volume of the pump chamber region of each volume calibration cassette and analyzing the multiple measurements. Determining a single value of the volume of the pump chamber region that serves as the corresponding measured volume. In some embodiments, analyzing the multiple measurements may include averaging the multiple measurements. In some embodiments, generating the calibration curve may include generating a best-fit equation. In some embodiments, generating the calibration curve may include generating a best-fit polynomial. In some embodiments, the best-fit polynomial may be a third-order polynomial. In some embodiments, generating the calibration curve may include performing a least-squares regression. In some embodiments, generating the calibration curve may include constraining at least one region of the curve to at least one limit. In some embodiments, the limit may be an acceptable range of derivative values ​​of points along the at least one region. In some embodiments, generating the calibration curve may include imposing constraints on allowed derivative values ​​( ) at zero crossings of the calibration curve. In some embodiments, measuring the known volume of the pump chamber region in each volume calibration cassette may include taking multiple measurements of the known volume of the pump chamber region of each volume calibration cassette and determining their conformance to a predefined standard, and analyzing the multiple measurements to determine a single value of the volume of the pump chamber region that serves as the corresponding measured volume. In some embodiments, the predefined standard may be a predefined allowable variation. In some embodiments, the predefined standard may be an allowed standard deviation. In some embodiments, the method may further include refining the calibration curve into a second calibration curve that accounts for volume measurement error due to the disposable pump cassette. In some embodiments, the method may further include refining the calibration curve into another calibration curve that accounts for volume measurement error due to head height of the fluid source or destination.

[0026] According to another embodiment of the present disclosure, a cassette-based pump system may include a fluid processing set including a pump cassette having a flexible membrane covering at least one pump chamber. The system may further include a cycler. The cycler may include a mounting location sized to receive the pump cassette and position the cassette relative to a control surface. The cycler may further include multiple pressure reservoirs. The cycler may further include a pressure delivery assembly for applying pressure from the pressure reservoirs to the pump cassette to pump fluid through the cassette. In addition to the pressure sensor, the pressure delivery assembly may have a control surface, a pneumatic channel, and a control chamber for actuating the flexible membrane, and at least one reference chamber of known volume for measuring the volume of the pump chamber. The pneumatic channel may be in selective communication with the pressure reservoir via several valves. The cycler may further include a controller configured to receive data from the pressure sensor, determine a raw measured amount of fluid pumped via the data, and adjust the raw measured amount of fluid pumped based at least in part on a cycler-specific calibration equation.

[0027] In some embodiments, the controller may be configured to adjust the raw measured volume of fluid pumped based at least in part on the cycler-specific calibration equation and the pump cassette volume error calibration equation. In some embodiments, the controller may be configured to adjust the raw measured volume of fluid pumped based at least in part on the cycler-specific calibration equation, the pump cassette volume error calibration equation, and the head height error calibration equation. In some embodiments, the cycler-specific calibration equation may be a best-fit polynomial through a data set of test measurements of a series of volumetric standard cassettes. In some embodiments, the controller may be configured to adjust the raw measured volume of fluid pumped based on a second calibration equation that may be a function of the cycler-specific calibration equation. In some embodiments, the second equation may be a pump cassette volume error calibration equation. In some embodiments, the controller may be configured to adjust the raw measured volume of fluid pumped based on a third calibration equation that may be a function of the second calibration equation. In some embodiments, the second equation may be a pump cassette volume error calibration equation, and the third equation may be a head height error calibration equation. In some embodiments, the second equation can be a head height error calibration equation and the third equation can be a pump cassette volume error calibration equation. In some embodiments, the controller can be configured to adjust the raw measured volume of fluid pumped based at least in part on the cycler-specific calibration equation and the second calibration equation. In some embodiments, the system may further include a database of pump cassette volume error calibration equations associated with the cassette-associated unique identifier. In some embodiments, the cycler may further include a user interface, and the controller may be configured to receive the cassette-associated unique identifier input via the user interface. The controller may be configured to communicate with the database to obtain the pump cassette volume error calibration equation associated with the cassette-associated unique identifier input. The pump cassette volume error calibration equation associated with the cassette-associated unique identifier input can be used as the second calibration equation. In some embodiments, the cycler may further include an imager. The controller may be configured to determine the cassette-associated unique identifier data via the imager data and to communicate with the database to obtain the pump cassette volume error calibration equation associated with the cassette-associated unique identifier data. The pump cassette volume error calibration equation associated with the cassette-associated unique identifier data can be used as the second calibration equation. In some embodiments, the fluid processing set may include a coded cassette-associated unique identifier.

[0028] According to another embodiment of the present disclosure, a cassette-based pump system may include a fluid processing set including a pump cassette having a flexible membrane covering at least one pump chamber and at least one cassette valve that gates fluid communication to a fluid reservoir. The system may further include a cycler including a pressure delivery assembly having at least one pump control chamber for actuating a portion of the flexible membrane covering the at least one pump chamber. The pressure delivery assembly may further include at least one valve control chamber for actuating a portion of the flexible membrane covering the at least one cassette valve. The pressure delivery assembly may further include at least one pressure sensor in communication with the at least one pump control chamber. The cycler may further include a pressure reservoir in selective communication with the at least one pump control chamber and the at least one valve control chamber via several pressure supply valves. The cycler may further include a controller configured to receive data from the at least one pressure sensor. The controller may be further configured to command the at least one cassette valve to an open state, monitor data from the at least one pressure sensor to identify first and second pressure peaks, and calculate a head height of the fluid reservoir based on the first and second pressure peaks.

[0029] In some embodiments, the controller may be further configured to determine a length of a fluid line coupling the fluid reservoir to the cassette based on time data associated with the first and second peaks. In some embodiments, the first peak may be an overshoot peak and the second peak may be an undershoot peak. In some embodiments, the controller may be further configured to adjust an operating parameter based on the calculated head height. In some embodiments, the operating parameter may be at least one pump pressure. In some embodiments, the controller may be further configured to refine the calibration curve based on the head height. In some embodiments, the fluid reservoir may be a dialysate reservoir. In some embodiments, the fluid reservoir may be a body cavity of the patient. In some embodiments, the controller may be further configured to displace a portion of a flexible membrane covering at least one pump chamber to a mid-stroke position before commanding the at least one cassette valve to an open state. In some embodiments, the controller may be further configured to determine a number of extension lines to be included in the fluid line coupling the fluid reservoir to the cassette based on time data associated with the first and second peaks. In some embodiments, the controller may be further configured to generate an error when the head height breaches a threshold. In some embodiments, the controller may be further configured to compare the head height to a predefined acceptable head height threshold.

[0030] According to another embodiment of the present disclosure, a method for selecting a pump pressure for a cassette-based pump system may include priming a fluid processing set installed in the pump system. The method may further include placing a pump chamber of a cassette of the fluid processing set in communication with a reservoir. The method may further include detecting a first pressure peak in a control chamber separated from the pump chamber by a membrane. The method may further include detecting a second pressure peak in the control chamber. The method may further include predicting a final pressure using the first and second pressure peaks. The method may further include calculating the pump pressure based on the predicted final pressure.

[0031] In some embodiments, the method may further include calculating a head height of the reservoir based on the predicted final pressure. In some embodiments, the method may further include determining a characteristic length of a fluid line connecting the reservoir based on cassette-based time data associated with the first and second peaks. In some embodiments, the method may further include determining a number of extensions to be included in the fluid path connecting the cassette to the reservoir based on the time data associated with the first and second peaks. In some embodiments, the method may further include generating an error if the predicted final pressure breaches a predetermined threshold. In some embodiments, the method may further include moving the membrane to a predetermined initial position. In some embodiments, the predetermined initial position may be a position that biases the head height detection range toward detecting a positive head height. In some embodiments, the predetermined initial position may be a position that biases the head height detection range toward detecting a negative head height. In some embodiments, the predetermined initial position may be a mid-stroke position. In some embodiments, the method may further include adjusting a calibration curve of the cassette-based pump system based on the predicted final pressure. In some embodiments, detecting the first peak may include calculating a difference between a set of consecutive data points from at least one pressure sensor in communication with the control room. In some embodiments, detecting the first peak may further include applying data smoothing to the set of consecutive data points forming the at least one pressure sensor. In some embodiments, the method may further include identifying the first peak when a difference between the set of consecutive data points is less than a predefined limit. In some embodiments, predicting the final pressure may include determining an overshoot percentage based on the first and second peaks.

[0032] According to another embodiment of the present disclosure, a method for checking head height of a reservoir coupled to a cassette-based pumping system may include placing a pumping chamber of a cassette of a fluid processing set installed in the cassette-based pumping system in communication with a reservoir. The method may further include detecting a first pressure peak in a control chamber separated from the pumping chamber by a membrane. The method may further include detecting a second pressure peak in the control chamber. The method may further include predicting a final pressure using the first and second pressure peaks. The method may further include comparing the predicted final pressure to at least one predetermined threshold. The method may further include generating a notification when the predicted final pressure breaches at least one of the at least one predetermined threshold.

[0033] In some embodiments, generating a notification may include generating an error. In some embodiments, generating the notification may include generating a screen for display on a user interface of the cassette-based pump system. In some embodiments, generating the notification may include generating an audible noise. In some embodiments, the method may further include calculating a reservoir head height based on the predicted final pressure. In some embodiments, the method may further include determining an overshoot percentage based on the first and second pressure peaks. In some embodiments, the method may further include determining a characteristic length of a fluid line connecting the reservoir to the cassette based on time data associated with the first and second peaks. In some embodiments, the method may further include determining a number of extensions to be included in the fluid path connecting the cassette to the reservoir based on time data associated with the first and second peaks. In some embodiments, the method may further include moving the membrane to a predetermined initial position. In some embodiments, the predetermined initial position may be a position that biases the head height detection range toward detecting a positive head height. In some embodiments, the predetermined initial position may be a position that biases the head height detection range toward detecting a negative head height. In some embodiments, the predetermined initial position may be a mid-stroke position. In some embodiments, the method may further include adjusting a calibration curve of the cassette-based pump system based on the predicted final pressure. In some embodiments, detecting the first peak may include calculating a difference between a set of consecutive data points from at least one pressure sensor in communication with the control room. In some embodiments, detecting the first peak may further include applying data smoothing to the set of consecutive data points from the at least one pressure sensor. In some embodiments, the method may further include identifying a first peak when the difference between a set of consecutive data points is less than a predefined limit.

[0034] According to another embodiment of the present disclosure, a cassette-based pump system may include a fluid processing set including a pump cassette having a flexible membrane covering at least one pump chamber and at least one cassette valve that gates fluid communication to a fluid reservoir. The system may further include a cycler including at least one pump control chamber. The cycler may further include at least one valve control chamber. The cycler may further include at least one pressure sensor in communication with the at least one pump control chamber. The cycler may further include a pressure reservoir in selective communication with the at least one pump control chamber and the at least one valve control chamber via several pressure supply valves. The cycler may further include a controller in data communication with the pressure sensor. The controller may be configured to command the at least one cassette valve to an open state, monitor data from the at least one pressure sensor, identify first and second pressure peaks, and predict a final pressure based on the first and second pressure peaks.

[0035] In some embodiments, the controller may be further configured to determine a length of a fluid line coupling the fluid reservoir to the cassette based on time data associated with the first and second peaks. In some embodiments, the first peak may be an overshoot peak and the second peak may be an undershoot peak. In some embodiments, the controller may be further configured to adjust an operating parameter based on the calculated head height. In some embodiments, the operating parameter may be at least one pump pressure. In some embodiments, the controller may be further configured to refine the calibration curve based on the head height. In some embodiments, the fluid reservoir may be a dialysate reservoir. In some embodiments, the fluid reservoir may be a body cavity of the patient. In some embodiments, the controller may be further configured to displace a portion of a flexible membrane covering at least one pump chamber to a mid-stroke position before commanding the at least one cassette valve to an open state. In some embodiments, the controller may be further configured to determine a number of extension lines to be included in the fluid line coupling the fluid reservoir to the cassette based on time data associated with the first and second peaks. In some embodiments, the controller may be further configured to generate an error when the predicted final pressure breaches a threshold. In some embodiments, the controller may be further configured to compare the predicted final pressure to a predefined acceptable head height pressure threshold.

[0036] According to another embodiment of the present disclosure, the fluid line condition detector may include a receptacle configured to hold a fluid line opaque to ultraviolet light. The fluid line condition detector may further include a light sensor. The fluid line condition detector may further include an infrared-emitting LED. The fluid line condition detector may further include an ultraviolet-emitting LED. The fluid line condition detector may further include a third LED. The fluid line condition detector may further include a controller in data communication with the light sensor. The controller may be configured to determine that the appropriate tube is present in the fluid line condition detector when the intensity of infrared light sensed by the light sensor from the infrared-emitting LED exceeds a predetermined first threshold and the intensity of ultraviolet light sensed by the light sensor from the ultraviolet-emitting LED is below a predetermined second threshold. The axis of the infrared-emitting LED and the axis of the ultraviolet-emitting LED may be parallel to each other and to the axis of the light sensor.

[0037] In some embodiments, the axis of the infrared-emitting LED can be the optical axis of the infrared-emitting LED, and the axis of the ultraviolet-emitting LED can be the optical axis of the ultraviolet-emitting LED. In some embodiments, the axis of the infrared-emitting LED can be the mechanical axis of the infrared-emitting LED, and the axis of the ultraviolet-emitting LED can be the mechanical axis of the ultraviolet-emitting LED. In some embodiments, the axis of the light sensor can be the optical axis of the light sensor. In some embodiments, the axis of the light sensor is the mechanical axis of the light sensor. In some embodiments, the third LED can be an infrared-emitting LED. In some embodiments, the axis of the third LED can be at an angle other than parallel to the axis of the infrared-emitting LED and the axis of the ultraviolet-emitting LED. In some embodiments, the axis of the ultraviolet-emitting LED can be configured to pass through a central portion of a fluid line installed in the receptacle. In some embodiments, the receptacle can include a retainer for holding the fluid line. In some embodiments, the controller can be further configured to determine that the fluid line is dry when the light intensity from the third LED exceeds a predetermined dryness threshold. In some embodiments, the controller may be further configured to determine that the fluid line is primed when the light intensity from the third LED falls below a predetermined primed threshold. The predetermined prime threshold may be lower than a predetermined dry threshold. In some embodiments, the controller may be further configured to determine that the fluid line is primed when the light intensity from the infrared-emitting LED falls below a predetermined infrared threshold and when the light intensity from the third LED falls below a predetermined priming threshold. The predetermined prime threshold may be lower than a predetermined dry threshold. In some embodiments, the controller may be configured to determine that the fluid line status detector has adequate tubing when the intensity of infrared light sensed by the light sensor from the infrared-emitting LED exceeds a predetermined first threshold, when the intensity of ultraviolet light sensed by the light sensor from the ultraviolet-emitting LED falls below a predetermined second threshold, and when the intensity of light emitted by the third LED falls below a predetermined third threshold.In some embodiments, the controller may be further configured to manage the supply of power to the infrared-emitting LED, the ultraviolet-emitting LED, and the third LED.

[0038] According to one embodiment of the present disclosure, a fluid line condition detector for detecting the presence of a fluid line that is opaque to light of a first spectrum and at least translucent to light of a second spectrum may include a receptacle configured to hold the fluid line. The fluid line condition detector may further include a light sensor. The fluid line condition detector may further include a first LED configured to emit light of the first spectrum. The fluid line condition detector may further include a second LED configured to emit light of the second spectrum. The fluid line condition detector may further include a third LED. The fluid line condition detector may further include a controller in data communication with the light sensor. The controller may be configured to determine the presence of a fluid line in the fluid line condition detector when the intensity of the light of the first spectrum sensed by the light sensor from the first LED falls below a predetermined first threshold and when the intensity of the light of the second spectrum sensed by the light sensor from the second LED exceeds a predetermined second threshold. The axis of the first LED and the axis of the second LED may be parallel to each other and to the axis of the light sensor.

[0039] In some embodiments, the axis of the first LED may be the optical axis of the first LED, and the axis of the second LED may be the optical axis of the second LED. In some embodiments, the axis of the first LED may be the mechanical axis of the first LED, and the axis of the second LED may be the mechanical axis of the second LED. In some embodiments, the axis of the light sensor may be the optical axis of the light sensor. In some embodiments, the axis of the light sensor may be the mechanical axis of the light sensor. In some embodiments, the third LED may be configured to emit light of a second spectrum. In some embodiments, the axis of the third LED may be at an angle other than parallel to the axis of the first LED and the axis of the second LED. In some embodiments, the axis of the first LED may be configured to pass through a central portion of the fluid line when the fluid line is installed in the receptacle. In some embodiments, the receptacle may include a retainer for holding the fluid line. In some embodiments, the controller may be further configured to determine that the fluid line is dry when the light intensity from the third LED exceeds a predetermined dryness threshold. In some embodiments, the controller may be further configured to determine that the fluid line is primed when the light intensity from the third LED falls below a predetermined primed threshold. The predetermined prime threshold may be lower than a predetermined dry threshold. In some embodiments, the controller may be further configured to determine that the fluid line is primed when the light intensity from the second LED falls below a predetermined second light spectrum threshold and when the light intensity from the third LED falls below a predetermined priming threshold. The primed threshold is lower than the predetermined dry threshold. In some embodiments, the controller may be configured to determine that a fluid line is present in the fluid line condition detector when the light intensity of the first spectrum sensed by the light sensor from the first LED falls below a predetermined first threshold, the light intensity of the second spectrum sensed by the light sensor from the second LED exceeds a predetermined second threshold, and the light intensity sensed by the light sensor from the third LED falls below a predetermined third threshold.In some embodiments, the controller may be further configured to manage the supply of power to the first, second, and third LEDs. In some embodiments, the first spectrum may be an ultraviolet spectrum. In some embodiments, the second spectrum may be an infrared spectrum. In some embodiments, the fluid line may be transparent to light of the second spectrum.

[0040] According to one embodiment of the present disclosure, a method for detecting the presence of a proper fluid line in a detector receptacle may include emitting light of a first spectrum from a first LED. The fluid line may be opaque to the light of the first spectrum. The method may further include emitting light of a second spectrum from a second LED. The fluid line may be at least translucent to the light of the second spectrum. The method may further include monitoring the intensity of the received light using a light sensor positioned on an opposite side of the receptacle from the first and second LEDs. The method may further include comparing the intensity of the light received in the first spectrum to a first threshold. The method may further include comparing the intensity of the light received in the second spectrum to a second threshold. The method may further include determining the presence of a proper fluid line when the intensity of the light of the first spectrum is less than the first threshold and the intensity of the light of the second spectrum is greater than the second threshold.

[0041] In some embodiments, the first threshold value may correspond to substantially no light transmission from the first LED to the light sensor. In some embodiments, the first spectrum may be an ultraviolet spectrum. In some embodiments, the second spectrum may be a higher wavelength spectrum than the first spectrum. In some embodiments, the second spectrum may be an infrared spectrum. In some embodiments, the fluid line may be transparent to light of the second spectrum. In some embodiments, the method may further include generating a notification when the intensity of the light of the first spectrum is greater than the first threshold value and the intensity of the light of the second spectrum is greater than the second threshold value. In some embodiments, generating the notification may include displaying a notification to reload the fluid line on a graphical user interface. In some embodiments, the axes of the first LED and the second LED may be parallel to each other and to the axis of the light sensor.

[0042] According to one embodiment of the present disclosure, a fluid pump system may include a pump. The fluid pump system may further include a displacement volume sensing assembly. The fluid pump system may further include a receptacle for holding a fluid line, a fluid line status detector having at least one optical sensor and at least one LED. The fluid pump system may further include a fluid transfer set including an output line configured to mate with the receptacle. The fluid pump system may further include at least one fluid source. The fluid pump system may further include a controller in data communication with the fluid line status detector. The controller may be configured to provide power to the at least one LED and monitor an output signal of the at least one optical sensor when the outlet line is installed in the receptacle to determine a light intensity value of the dry tube. The controller may be further configured to control operation of the pump to prime the output line with fluid from the at least one fluid source. The controller may be further configured to provide power to the at least one LED, monitor the output signal, and stop operation of the pump when the output signal indicates that the light intensity value has fallen below a primed line threshold. The primed line threshold may be calculated by the controller based on the dry tube intensity reading.

[0043] In some embodiments, the primed line threshold may be calculated by adding a constant to a percentage of the dry tube intensity value. In some embodiments, the controller may be further configured to power at least one LED multiple times. The dry tube intensity value may be based on a maximum light intensity value output from the light sensor multiple times. In some embodiments, the controller may be configured to power at least one LED multiple times and monitor the output signal to determine the maximum light intensity value. The dry tube intensity value may be based on the maximum light intensity value and at least one limit. In some embodiments, the limit may be a minimum value of the dry tube intensity value. In some embodiments, the controller may be further configured to generate a notification when the displaced fluid sensing assembly indicates that the volume of displaced fluid is greater than a predefined threshold. In some embodiments, the controller may be configured to continue pumping upon receiving a user input from a user interface of the system indicating that the output line is not yet fully primed. In some embodiments, the pump may be a diaphragm pump. In some embodiments, the pump may be a pneumatic diaphragm pump. In some embodiments, a portion of the pump may be included in a fluid transfer set. In some embodiments, a portion of the pump may be included in a fluid treatment cassette of a fluid transfer set. In some embodiments, the fluid transfer set may include a fluid treatment cassette with at least one pump chamber, each of the at least one pump chamber forming a portion of the pump. In some embodiments, the at least one fluid source may be a dialysate reservoir. In some embodiments, the at least one LED may include a first LED positioned at an angle relative to the optical axis of the optical sensor. In some embodiments, the at least on LEDs may include a second LED and a third LED. In some embodiments, the axis of the second LED and the axis of the third LED may be parallel to the optical axis of the optical sensor.

[0044] According to another embodiment of the present disclosure, a method for priming a fluid line may include installing the fluid line in a receptacle of a fluid line condition detector. The method may further include emitting light from at least one LED of the fluid line condition detector a first plurality of times. The method may further include monitoring an output signal of a light sensor of the fluid line condition detector and determining a maximum light intensity value based on the output signal during the first plurality of times. The method may further include determining a primed line threshold based on the maximum light intensity value. The method may further include pumping fluid through the fluid line. The method may further include emitting light from at least one LED of the fluid line condition detector a second plurality of times. The method may further include determining that the fluid line is primed when the output signal of the light sensor indicates that the light intensity from the LED has breached a primed line threshold.

[0045] In some embodiments, placing the fluid line in the receptacle may include seating the fluid line within a channel of the fluid line status detector. In some embodiments, the method may further include comparing the maximum light intensity to a limit and, if the maximum light intensity value does not meet the limit, overriding the maximum light intensity value with the limit value. In some embodiments, determining the maximum light intensity value based on the output signal may include comparing the light intensity value indicated by the output signal during the first plurality of times to a calibrated value to determine a ratio. In some embodiments, the calibrated value may be a light intensity value from at least one LED output from the light sensor when no tubing is attached to the receptacle. In some embodiments, determining a threshold for a primed line may include adding a constant to a percentage of the maximum light intensity value. In some embodiments, the second plurality of times may occur during the process of pumping fluid through the line. In some embodiments, emitting light from at least one LED during the second plurality of times may include emitting light from the first, second, and third LEDs. In some embodiments, the method may further include stopping pumping of fluid through the line upon determining that the fluid line is primed. In some embodiments, the method may further include monitoring the volume of fluid being pumped via the displaced volume sensing assembly. In some embodiments, the method may further include pausing pumping of fluid when the amount of fluid being pumped exceeds a first volume threshold. In some embodiments, the method may further include resuming pumping upon receiving user input indicating that the line is not yet fully primed. In some embodiments, the method may further include inhibiting resumption of the pump if the amount of fluid being pumped exceeds a second volume threshold.

[0046] According to another embodiment of the present disclosure, a fluid pump system may include a pump. The fluid pump system may further include a fluid line condition detector having a receptacle, at least one sensor, and at least one illuminator. The fluid pump system may further include a fluid transfer set including an output line configured to mate with the receptacle. The fluid pump system may further include a controller in data communication with the fluid line condition detector. The controller may be configured to provide power to the at least one illuminator and monitor an output signal of the at least one sensor when the outlet line is installed in the receptacle to determine a light intensity value of the dry tube. The controller may be further configured to control operation of the pump to prime the output line with fluid from the at least one fluid source. The controller may be further configured to provide power to the at least one illuminator, monitor the output signal, and stop operation of the pump when the output signal indicates that the light intensity value has fallen below a prime line threshold that is dependent on the dry tube intensity value.

[0047] In some embodiments, the primed line threshold may be calculated by adding a constant to a percentage of the dry tube light intensity value. In some embodiments, the controller may be configured to power the at least one illuminator multiple times, where the dry tube light intensity value is based on a maximum light intensity value output from the sensor over the multiple times. In some embodiments, the controller may be configured to power the at least one illuminator multiple times and monitor the output signal to determine a maximum light intensity value, where the dry tube light intensity value is based on the maximum light intensity value and at least one limit. In some embodiments, the limit may be a minimum value of the dry tube light intensity value. In some embodiments, the system may further include a displacement volume sensing assembly. The controller may be further configured to generate a notification when the displacement volume sensing assembly indicates that the displaced fluid volume is greater than a predefined threshold. In some embodiments, the controller may be configured to continue pumping upon receiving a user input from a user interface of the system indicating that the output line is not yet fully primed. In some embodiments, the pump may be a diaphragm pump. In some embodiments, the pump may be a pneumatic diaphragm pump. In some embodiments, a portion of the pump may be included in a fluid transfer set. In some embodiments, the at least one fluid source may be a dialysate reservoir. In some embodiments, the at least one illuminator may include a first LED positioned at an angle relative to an optical axis of the sensor. In some embodiments, the at least one illuminator may include a second LED and a third LED, and in some embodiments, the axis of the second LED and the axis of the third LED may be parallel to the optical axis of the sensor. [Brief explanation of the drawings]

[0048] Aspects of the present invention are described below, at least in part, with reference to the exemplary embodiments illustrated in the following drawings, in which like numerals refer to like elements and in which: [Figure 1A]1 shows a schematic diagram of an automated peritoneal dialysis (APD) system incorporating one or more embodiments of the present invention. [Figure 1B] 1B illustrates an alternative configuration to the dialysate delivery set shown in FIG. 1A. [Figure 2] FIG. 2 is a schematic diagram of an exemplary set used in the APD system of FIG. 1. [Figure 3] FIG. 2 is an exploded perspective view of the cassette according to the first embodiment. [Figure 4] 4 is a cross-sectional view of the cassette taken along line 4-4 in FIG. 3. [Figure 5] FIG. 1 is a perspective view of a vacuum forming mold that can be used to form a membrane having a preformed pumping chamber portion in an exemplary embodiment. [Figure 6] FIG. 4 shows a front view of the cassette body of FIG. 3. [Figure 7] 10A-10C are front views of a cassette body including two different spacer arrangements in an exemplary embodiment. [Figure 8] FIG. 4 is a rear perspective view of the cassette body of FIG. 3. [Figure 9] FIG. 4 is a rear view of the cassette body of FIG. 3. [Figure 10] 1 is a front perspective view of an exemplary configuration of a fluid line condition detector or liquid level detector. FIG. [Figure 11] FIG. 1 is a rear perspective view of a fluid line condition detector or liquid level detector. [Figure 12] FIG. 1 is a perspective layout diagram of three LEDs and an optical detector surface-mounted on a printed circuit board. [Figure 13] FIG. 1 is a plan view of three LEDs and an optical detector mounted on a detector circuit board. [Figure 14] FIG. 11 is an exploded perspective view of the detector of FIG. 10 showing the printed circuit board and transparent or translucent plastic insert. [Figure 15] 11 is a graph illustrating the ability of the liquid level detector of FIG. 10 to distinguish between primed and unprimed fluid lines. [Figure 16]10 is a graph showing measurements detected by an optical sensor comparing liquid detection using angled LEDs versus orthogonally oriented LEDs. [Figure 17] 11 is a graph illustrating the ability of the liquid level detector of FIG. 10 to distinguish between the presence and absence of a pipe segment within the detector. [Figure 18] 11 is a graph showing the range of signals corresponding to primed and unprimed fluid lines for various cyclers using the liquid detector of FIG. 10. [Figure 19] 1 is a flowchart illustrating several example actions that may be performed to prime a fluid line. [Figure 20] 10 is a perspective view of an alternative configuration of the liquid level detector; FIG. [Figure 21] 1 illustrates an embodiment of a fluid line cap, a fluid line, and a fluid line connector. [Figure 22] 1 illustrates an embodiment of a fluid line cap, a fluid line, and a fluid line connector. [Figure 23] 10 illustrates another embodiment of a fluid line cap, a fluid line, and a fluid line connector. [Figure 24] 10 illustrates another embodiment of a fluid line cap, a fluid line, and a fluid line connector. [Figure 25] 1 illustrates an example of a fluid line cap that includes a notch. [Figure 26] 1 illustrates an example of a fluid line cap that includes a restriction. [Figure 27] 26A shows a cross-sectional view of the fluid line cap taken along line 26-26 of FIG. 26. [Figure 28] 1 illustrates an example of a fluid line cap installed on a fluid line connector of a fluid line. [Figure 29] 28 shows a cross-sectional view of the fluid line cap, fluid line, and fluid line connector of FIG. 27 taken along line 28-28 of FIG. 28. [Figure 30] A flowchart outlining several steps a cycler can use to prime a line with a two-part prime is shown. [Figure 31] FIG. 2 is a perspective view of the APD system of FIG. 1 with the cycler door open. [Figure 32] FIG. 32 is a front view of the control surface of the cycler for interacting with the cassette in the embodiment of FIG. 31. [Figure 33A] FIG. 12 is a front view of an embodiment of a control surface of the cycler. [Figure 33B] 33B shows a selected cross-sectional view of FIG. 33A. [Figure 33C] 33B shows a selected cross-sectional view of FIG. 33A. [Figure 34] FIG. 33 is an exploded view of an assembly for the interface of FIG. 32 with a mating pressure supply block and pressure distribution module. [Figure 35] 1 shows an exploded view of a control gasket inserted between the pressure supply block and the pump cassette of the base unit. [Figure 36] FIG. 1 is an exploded view of an integrated manifold. [Figure 37] Two isometric views of the integrated manifold are shown. [Figure 38] 1 shows a schematic diagram of the pneumatic system controlling fluid flow through the cycler. [Figure 39] FIG. 10 is a front side view of an embodiment of a cassette fixture. [Figure 40] 4 shows another example of a cassette fixture made from a modified cassette such as the cassette shown in FIG. 3. [Figure 41] 10 shows another example of a cassette fixture made from a modified cassette cassette. [Figure 42] 1 shows pressure tracing from the control or actuation chamber of the pump cassette during a liquid delivery stroke. [Figure 43] FIG. 10 is a schematic diagram of the pump chamber of the cassette and associated control components and inflow / outflow paths in an exemplary embodiment. [Figure 44] 44 is a plot of exemplary pressure readings for the control and reference chambers from a time before valve X2 is opened to some time after valve X2 is opened for the embodiment of FIG. 43. [Figure 45]FIG. 10 is a schematic diagram of an exemplary embodiment of a cassette control chamber and associated control components including pressure sensors and inlet / outlet paths. [Figure 46] 10 is a pressure versus time plot for the reference and control chambers during the pumping and FMS process. [Figure 47] 1 is a flow chart of the pneumatic steps of the FMS process. [Figure 48A] 10 is a plot of the pressure in the pump chamber and the reference chamber during the +FMS process. [Figure 48B] 10 is a plot of the pressure in the pump chamber and the reference chamber during the FMS process. [Figure 49A] FIG. 1 is a diagram of a polytropic conceptual model of the +FMS process, which includes three separate closed mass systems. [Figure 49B] 10 is a plot of the polytropic expansion constant for +FMS versus control room volume. [Figure 50A] FIG. 1 is a diagram of a polytropic conceptual model of the FMS process, involving three separate closed mass systems. [Figure 50B] 10 is a plot of the polytropic expansion constant for the -FMS case versus the control room mass. [Figure 51] 1 is a flowchart of the basic AIA FMS calculation steps. [Figure 52] 1 is a more detailed flowchart of the AIA FMS calculation steps. [Figure 53A] 1 is a flowchart of an FMS calibration method for a diaphragm pump. [Figure 53B] 10 is a flowchart for calibrating partial stroke volume for the FMS calibration method. [Figure 54] FIG. 1 is a diagram of a process used to calibrate part-stroke volume in a diaphragm pump. [Figure 55] FIG. 10 is a diagram of the correction of volume measurements during partial stroke calibration as the pump diaphragm approaches the chamber wall. [Figure 56] 10 shows a pressure trace from the control or actuation chamber of the pump cassette during a liquid delivery stroke. [Figure 57] 1 shows a graph plotting pressure in the control or actuation chamber during a liquid delivery stroke, and a cumulative volume estimation plot during the liquid delivery stroke. [Figure 58] 1 shows a flowchart outlining steps that can be used to estimate control room volume change over time. [Figure 59] 1 shows a flowchart outlining the steps for adjusting the equation used to estimate control chamber volume change over time during a pump stroke. [Figure 60] 1 shows a flowchart outlining the steps for detecting the end of a stroke based on flow rate during the stroke. [Figure 61] 1 shows a flowchart outlining the steps for determining the end of a stroke by predicting the time required to complete the stroke. [Figure 62] 1 shows a flowchart outlining the steps for detecting a reduced flow condition while a pump stroke is in progress. [Figure 63A] 1 illustrates a top view of an exemplary disposable fluid pump cassette. [Figure 63B] A cross-sectional view taken along line 63B-63B of Figure 63A is shown. [Figure 63C] A cross-sectional view taken along line 63C-63C of Figure 63A is shown. [Figure 64A] 1 shows a top view of an exemplary set of capacitance measurement standards. [Figure 64B] A cross-sectional view taken along line 64B-64B of Figure 64A is shown. [Figure 64C] A cross-sectional view taken along line 64C-64C of Figure 64A is shown. [Figure 64D] 1 illustrates a perspective view of an exemplary volumetric standard cassette. [Figure 65A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 65B] FIG. 65B shows a top view of the volumetric standard cassette shown in FIG. 65A. [Figure 66A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 66B] FIG. 66B shows a top view of the volumetric standard cassette shown in FIG. 66A. [Figure 67A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 67B] FIG. 67B shows a top view of the volumetric standard cassette shown in FIG. 67A. [Figure 68A] 65B illustrates a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 65A. [Figure 68B] 66B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 66A. [Figure 68C] 67B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 67A. [Figure 69A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 69B] FIG. 69B shows a top view of the volumetric standard cassette shown in FIG. 69A. [Figure 70A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 70B] FIG. 70B shows a top view of the volumetric standard cassette shown in FIG. 70A. [Figure 71A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 71B] FIG. 71B shows a top view of the volumetric standard cassette shown in FIG. 71A. [Figure 72A] 1 illustrates a perspective view of another exemplary volumetric standard cassette. [Figure 72B] FIG. 72B shows a top view of the volumetric standard cassette shown in FIG. 72A. [Figure 73A] 69B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 69A. [Figure 73B] 70B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 70A. [Figure 73C] 71B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 71A. [Figure 73D] 72B shows a cross-sectional view of the exemplary capacitance measurement standard set shown in FIG. 72A. [Figure 74]1 shows a flowchart detailing some exemplary actions that may be performed to perform a calibration using one or more volumetric calibration cassettes. [Figure 75] 10 shows a graph illustrating an exemplary calibration curve for the cycler's control room. [Figure 76] 1 shows an exemplary graph illustrating several calibration curves that may be used by the cycler. [Figure 77] 10 shows a flowchart illustrating some exemplary actions that can be used to refine a cycler's calibration curve. [Figure 78] 10 shows a flowchart illustrating some exemplary actions that may be used to refine the calibration curve for a particular cycler based on information related to the disposable cassette that is about to be used in the impending treatment. [Figure 79] 10 shows a flowchart illustrating some exemplary actions that may be used to test a production lot of disposable cassettes during manufacturing. [Figure 80] 10 shows a flowchart detailing some example actions that may be performed to detect the head height of a component of interest in a system. [Figure 81] 10 shows a flowchart detailing some exemplary actions that may be performed to adjust pump pressure based on a determined head height of a component of interest. [Figure 82] 10 shows a flowchart detailing some exemplary actions that may be performed during head height detection of a component of interest in the system. [Figure 83] 10 shows a flowchart detailing some exemplary actions that may be performed during head height detection of a component of interest in the system. [Figure 84] 10 shows a representative view of the pump chamber after finishing a delivery stroke to a destination at different head heights. [Figure 85] 10 shows a representative view of the pump chamber after finishing a delivery stroke to a destination at different head heights. [Figure 86] 10 shows a flowchart detailing several actions that may be used to determine a calibration curve for a particular head height. DETAILED DESCRIPTION OF THE INVENTION

[0049]

[0050] Automated Peritoneal Dialysis System 1A illustrates an automated peritoneal dialysis (APD) system 10 incorporating one or more aspects of the disclosure. Other APD systems or components thereof, such as those shown and described in U.S. Patent No. 10,058,694 to Norris et al., entitled "Medical Systems and Methods Using Multiple Fluid Lines," filed June 5, 2015 (Attorney Docket No. Q21), which is incorporated herein by reference in its entirety, may also be used with various embodiments of the disclosure detailed herein.

[0051] As shown in FIG. 1A , for example, system 10 in this exemplary embodiment includes a dialysate delivery set 12 (which in some embodiments may be a disposable set), a cycler 14 that interacts with delivery set 12 to pump fluid provided by solution container 20 (e.g., a bag), and a control system 16 (e.g., including a programmed computer or other data processor, computer memory, an interface that provides information to and receives input from a user or other device, one or more sensors, actuators, relays, a pneumatic pump, a tank, a power source, and / or other suitable components) that manages the process to perform APD treatment. While FIG. 1 shows only a few buttons for receiving user control input, further details regarding the control system components are provided below. In this exemplary embodiment, cycler 14 and control system 16 are associated with a common housing 82, but may be associated with two or more housings and / or may be separate from one another. The cycler 14 may have a compact footprint suitable for operation on a tabletop or other relatively small surface typically found in the home. The cycler 14 is lightweight and portable, and can be carried by hand, for example, via handles on either side of the housing 82 .

[0052] Set 12 is intended to be a single-use, disposable item in this embodiment, but could instead have one or more reusable parts or be reusable in its entirety. A user associates set 12 with cycler 14 before beginning each APD therapy session, for example, by installing cassette 24 in front door 141 of cycler 14, and cycler 14 interacts with cassette 24 to pump and control fluid flow in various lines of set 12. For example, to perform APD, dialysate can be pumped to and from a patient. After therapy, a user can remove all or some of the components of set 12 from cycler 14.

[0053] As is known in the art, prior to use, a user can connect the patient line 34 of the set 12 to their own indwelling peritoneal catheter (not shown) at connection 36. In one embodiment, the cycler 14 can be configured to operate with one or more different types of cassettes 24, such as those having different sized patient lines 34. For example, the cycler 14 can be configured to operate with a first type of cassette with a patient line 34 sized for use with adult patients and a second type of cassette with a patient line 34 sized for use with infants or children. The pediatric patient line 34 can be shorter and have a smaller inner diameter than the adult line to minimize line volume, allowing for more controlled delivery of dialysate and helping to avoid returning relatively large amounts of used dialysate to the pediatric patient when the set 12 is used in successive drain and fill cycles. A heater bag 22, connected to the cassette 24 by a line 26, can be placed on the heater vessel receiving portion (in this case, a tray) 142 of the cycler 14. The cycler 14 can pump fresh dialysate (via the cassette 24) into the heater bag 22, which can then heat the dialysate to a temperature of approximately 37° C. by the heater tray 142, for example, by an electrical resistance heating element associated with the tray 142. The heated dialysate can be provided to the patient from the heater bag 22 via the cassette 24 and the patient line 34. In an alternative embodiment, the dialysate can be heated on its way to the patient, as it enters the cassette 24, or after it leaves the cassette 24, by passing it through tubing in contact with the heater tray 142 or through an in-line fluid heater (which can be provided in the cassette 24). Spent dialysate can be pumped from the patient through the patient line 34 to the cassette 24 and into the drain line 28, which can include one or more clamps that control flow through one or more branches of the drain line 28.In this exemplary embodiment, the drain line 28 can include a connector 39 connecting the drain line 28 to a dedicated drain receptacle and an effluent sample port 282 for obtaining a sample of used dialysate for testing or other analysis. A user can also install the lines 30 of one or more containers 20 within the door 141. The lines 30 can also be connected to a continuous or real-time dialysate preparation system. (The lines 26, 28, 30, and 34 can include flexible tubing and / or suitable connectors and other components, such as pinch valves, as desired.) The container 20 can contain sterile peritoneal dialysis fluid to be infused or other substances (e.g., substances used by the cycler 14 to formulate dialysate by mixing with water or different types of dialysate). The lines 30 can be connected to a spike 160 on the cassette 24, which is covered by a removable cap in FIG. 1A .

[0054] In one aspect of the present invention, the cycler 14 can automatically remove the caps from one or more spikes 160 of the cassette 24 and connect the lines 30 of the solution containers 20 to the respective spikes 160. This feature can help reduce the chance of contact of non-sterile items with the spikes 160, thereby reducing the possibility of infection or contamination.

[0055] In another embodiment, the dialysate delivery set 12A may not have a cassette spike 160. Instead, one or more solution lines 30 may be permanently attached to the inlet port of the cassette 24, as shown in FIG. 1B. In this case, each solution line 30 may have a spike connector 35 (with a cap) for manual connection to a solution container or dialysate bag 20.

[0056] By making various connections, the control system 16 can pace the cycler 14 through a series of fill, dwell, and / or drain cycles typical of an APD treatment. For example, during a fill phase, the cycler 14 can pump dialysate (via cassette 24) from one or more containers 20 (or other dialysate sources) into heater bag 22 for heating. The cycler 14 can then infuse the heated dialysate from heater bag 22, through cassette 24, and into the patient's peritoneal cavity via patient line 34. Following the dwell phase, the cycler 14 can begin a drain phase, during which the cycler 14 pumps spent dialysate from the patient via line 34 (again via cassette 24) and drains the spent dialysate via drain line 28 into a nearby drain (not shown).

[0057] The cycler 14 does not necessarily require that the solution container 20 and / or heater bag 22 be positioned at a defined head height above the cycler 14, for example, because the cycler 14 is not necessarily a gravity-flow system. Instead, the cycler 14 can mimic gravity flow or otherwise suitably control the flow of dialysate, such as when the source solution container 20 is above, below, or at the same height as the cycler 14 and the patient is above or below the cycler. For example, the cycler 14 can mimic a fixed head height during a given treatment, or the cycler 14 can vary the effective head height to increase or decrease the pressure applied to the dialysate during treatment. The cycler 14 can also adjust the flow rate of the dialysate. In one aspect of the present invention, the cycler 14 can adjust the pressure and / or flow rate of the dialysate as it is provided to or withdrawn from the patient to reduce the patient's perception of filling or draining. Such adjustments can be made during a single fill and / or drain cycle, or can be adjusted across different fill and / or drain cycles. In one embodiment, the cycler 14 can gradually reduce the pressure used to draw spent dialysate from the patient near the end of the drain operation. Because the cycler 14 can establish an artificial head height, it has the flexibility to interact with and adapt to changes in a patient's particular physiology or relative height.

[0058] cassette In one embodiment of the present invention, the cassette 24 can include patient and drain lines that are separately occludable relative to the solution supply lines. That is, safety-critical flow to and from the patient lines can be controlled, for example, by pinching the lines to stop flow without having to occlude flow through one or more of the solution supply lines. This feature can enable a simplified occluder device because occlusion can be performed with respect to only two lines, as opposed to occluding other lines, which has little or no impact on patient safety. For example, in situations where the patient or drain connection is isolated, the patient and drain lines can be occluded. However, the solution supply and / or heater bag lines can remain fluidly open, allowing the cycler 14 to prepare for the next dialysis cycle; for example, separate occlusion of the patient and drain lines can help ensure patient safety while allowing the cycler 14 to continue pumping dialysate from one or more containers 20 to the heater bag 22 or other solution containers 20.

[0059] In another aspect of the invention, a cassette can have patient lines, drain lines, and heater bag lines on one side or portion of the cassette and one or more solution supply lines on another side or portion of the cassette, e.g., the opposite side of the cassette. This arrangement can allow for separate occlusion of the patient lines, drain lines, or heater bag lines with respect to the solution lines, as described above. Physically separating the lines attached to the cassette by type or function allows for more efficient control of interactions with lines of a given type or function. For example, this arrangement can allow for simplified occluder design, since less force is required to occlude one, two, or three of these lines than all lines leading to or from the cassette. Alternatively, this arrangement can allow for more effective automatic connection of solution supply lines to the cassette, as described in more detail below. That is, the solution supply lines and their respective connections are located away from the patient lines, drain lines and / or heater bag lines so that the automated uncapping and connection device can remove the caps from the spikes of the cassette, as well as remove the caps from the solution supply lines and connect the lines to their respective spikes without interference from the patient lines, drain lines or heater bag lines.

[0060] FIG. 2 illustrates an exemplary embodiment of a cassette 24 incorporating aspects of the present invention described above. In this embodiment, cassette 24 has a generally planar body with heater bag line 26, drain line 28, and patient line 34 connected to respective ports on the left end of the cassette body, and the right end of the cassette body includes five spikes 160 to which solution supply lines 30 can be connected. In the arrangement shown in FIG. 2 , spikes 160 are each covered by a spike cap 63, which can be removed to expose the respective spike and enable connection to the respective line 30. As mentioned above, lines 30 can be attached to one or more solution containers or other sources of material, for example, for use in dialysis and / or dialysate formulation, and can be connected to one or more collection bags for sampling purposes or for a peritoneal equilibration test (PET test).

[0061] 3 and 4 show exploded views (perspective and top views, respectively) of cassette 24 in this exemplary embodiment. Cassette 24 is formed as a relatively thin, flat member having a generally planar shape and may include components molded, extruded, or otherwise formed from a suitable plastic. In this embodiment, cassette 24 includes a base member 18 that serves as a frame or structural member for cassette 24 and at least partially defines the various flow paths, ports, valves, etc. Base member 18 may be molded or otherwise formed from a suitable plastic or other material, such as polymethyl methacrylate (PMMA) acrylic resin or cyclic olefin copolymer / ultra-low density polyethylene (COC / ULDPE), and may be relatively rigid. In an embodiment, the ratio of COC to ULDPE may be approximately 85% / 15%. FIG. 3 also shows a heater bag port (port 150), a drainage port (port 152), and a patient port (port 154) formed in base member 18. Each of these ports may be positioned in any suitable manner, such as, for example, a central tube 156 extending from an outer ring or skirt 158, or the central tube alone. Flexible tubing for each of the heater bag line 26, drain line 28, and patient line 34 may connect to the central tube 156 and, if present, engage the outer ring 158.

[0062] Both sides of base member 18 can be covered by membranes 15 and 16, e.g., flexible polymeric films made from, for example, cast, extruded, or otherwise formed polyvinyl chloride (PVC). Alternatively, they can be formed as a laminate of two or more layers of, for example, polycyclohexylene dimethylene cyclohexane dicarboxylate (PCCE) and / or ULDPE, held together by a coextrudable adhesive (CXA). In some embodiments, membrane thicknesses can range from approximately 0.002 inches to 0.020 inches thick. In preferred embodiments, the thickness of the PVC-based membrane can range from approximately 0.012 inches to 0.016 inches thick, more preferably approximately 0.014 inches thick. In another preferred embodiment, such as a laminate sheet, the thickness of the laminate can range from approximately 0.006 inches to 0.010 inches thick, more preferably approximately 0.008 inches thick.

[0063] Both membranes 15 and 16 can function to close or otherwise form portions of the flow paths of cassette 24, as well as move or otherwise manipulate to open / close valve ports and / or function as part of pump diaphragms, partitions, or walls that move fluid within cassette 24. For example, membranes 15 and 16 can be disposed on base member 18 and sealed (e.g., by heat, adhesive, ultrasonic welding, or other means) to a rim around the periphery of base member 18 to prevent fluid leakage from cassette 24. Membrane 15 can also be bonded to other interior walls of base member 18, such as those that form the various channels, or can be pressed into sealing contact with walls and other features of base member 18 when cassette 24 is suitably mounted in cycler 14. Thus, both membranes 15 and 16 may be sealed to the peripheral rim of base member 18, for example to help prevent leakage of fluid from cassette 24 upon removal from cycler 14 after use, but may be positioned so as to lie free from contact with other portions of base member 18. Cassette 24 positioned within cycler 14 may be squeezed between opposing gaskets or other members, whereby membranes 15 and 16 are pressed into sealing contact with base member 18 in the areas inside their peripheries, thereby suitably sealing channels, valve ports, etc. from one another.

[0064] Other configurations for membranes 15 and 16 are possible. For example, membrane 16 can be formed by a rigid sheet of material that is bonded to or otherwise integrated with body 18. Thus, membrane 16 need not necessarily be or include a flexible member. Similarly, membrane 15 need not be flexible over its entire surface, but instead can include one or more flexible portions to allow pumping and / or valving, and one or more rigid portions, for example, to close off flow paths in cassette 24. For example, if cycler 14 includes suitable members for sealing passages, such as cassettes, control valves, and pumping functions, it is possible that cassette 24 may not include membrane 16 or membrane 15.

[0065] According to another aspect of the invention, the membrane 15 can include a pump chamber portion 151 ("pump membrane") that is formed to have a shape that closely matches the shape of the recess of a corresponding pump chamber 181 in the base 18. For example, the membrane 15 can be generally formed as a flat member having a thermoformed (or otherwise formed) dome-like shape 151 that matches the shape of the pump chamber recess in the base member 18. The dome-like shape of the preformed pump chamber portion 151 can be constructed, for example, by heating and molding the membrane over a vacuum forming mold of the type shown in FIG. 5. As shown in FIG. 5, a vacuum can be applied through a collection of holes along the walls of the mold. Alternatively, the walls of the mold can be constructed from a porous, gas-permeable material, which may result in a more uniformly smooth surface for the molded membrane. In one example, the molded membrane sheet 15 is trimmed while attached to the vacuum forming mold. The vacuum forming mold then presses the trimmed membrane sheet 15 against the cassette body 18, bonding them together. In one embodiment, the membrane sheets 15, 16 are , and is heat-welded to cassette body 18. In this manner, membrane 15 is able to move relative to pump chamber 181 to pump pressure without requiring stretching of membrane 15 (or at least with minimal stretching of membrane 15) both when membrane 15 is moved fully into pump chamber 181 and (possibly) into contact with spacer element 50 (e.g., as shown by the solid lines in FIG. 4 while pumping fluid out of pump chamber 181) and when membrane 15 is fully withdrawn from pump chamber 181 (e.g., as shown by the dashed lines in FIG. 4 while drawing fluid into pump chamber 181). Avoiding stretching of membrane 15 can help prevent pressure surges or other changes in fluid delivery pressure due to sheet stretching and / or can help simplify pump control when attempting to minimize pressure fluctuations during pump operation. Other benefits can be found, including reduced likelihood of membrane 15 damage (e.g., due to membrane 15 tearing resulting from stresses placed on membrane 15 during stretching) and / or improved accuracy in pump delivery volume measurement, as described in more detail below.In one embodiment, the pump chamber portion 151 can be formed to have a size (e.g., define a volume) that is approximately 85% to 110% of the pump chamber 181, for example, where the pump chamber portion 151 defines a volume that is approximately 100% of the pump chamber volume, and the pump chamber portion 151 can be positioned within the pump chamber 181 and in contact with the spacer 50 without being subjected to stress while at rest.

[0066] Providing greater control over the pressure used to generate the fill and delivery strokes of fluid in and out of the pump chamber can have several advantages. For example, during the drain cycle, it may be desirable to apply the smallest possible negative pressure when the pump chamber draws fluid from the patient's peritoneal cavity. Patients can be uncomfortable during the drain cycle of therapy due in part to the negative pressure applied by the pump during the fill stroke. The additional control that a preformed membrane can provide over the negative pressure applied during the fill stroke can help reduce patient discomfort.

[0067] The use of a pump membrane pre-shaped to the contours of the cassette pump chamber can realize several other advantages. For example, the flow rate of liquid through the pump chamber can be more uniform because a constant pressure or vacuum can be applied throughout the pump stroke, thereby simplifying the process of regulating liquid heating. Furthermore, temperature changes within the cassette pump, along with the dynamics of membrane displacement, have a smaller effect on the accuracy of measuring the pressure within the pump chamber. Furthermore, pressure spikes within the fluid line can be minimized. It also makes it simpler to correlate the pressure measured by a pressure transducer on the control (e.g., pneumatic) side of the membrane with the actual pressure of the liquid on the pump chamber side of the membrane. This allows for more accurate head height measurements of the patient and fluid source bag prior to treatment, improves sensitivity for detecting air in the pump chamber, and improves the accuracy of volumetric measurements. Furthermore, eliminating the need for membrane stretching can allow for the construction and use of chambers with larger volumes.

[0068] In this embodiment, cassette 24 includes multiple pump chambers 181 formed in base member 18, although one pump chamber or three or more pump chambers are possible. According to aspects of the invention, the inner walls of pump chambers 181 include spacer elements 50 that are spaced apart from one another and extend from the inner walls of pump chamber 181 to help prevent portions of membrane 15 from contacting the inner walls of pump chamber 181. (As shown for right pump chamber 181 in FIG. 4 , the inner walls are defined by side 181 a and bottom 181 b. Spacer 50 extends upward from bottom 181 b in this embodiment, but could extend from side 181 a or be otherwise formed.) By preventing membrane 15 from contacting the pump chamber inner walls, spacer elements 50 can provide dead space (or trapped volume) that can trap air or other gas within pump chamber 181 and help inhibit gas from being pumped out of pump chamber 181 in some circumstances. In other cases, the spacer 50 can aid in the movement of gas to the outlet of the pumping chamber 181, thereby removing gas from the pumping chamber 181, for example, during priming. The spacer 50 can also help prevent the membrane 15 from adhering to the pumping chamber walls and / or allow flow to continue through the pumping chamber 181, even when the membrane 15 is pressed into contact with the gas spacer element 50. Furthermore, the spacer 50 helps prevent premature closure of the pumping chamber outlet ports (openings 187 and / or 191) if the membrane accidentally makes uneven contact with the pumping chamber walls. Further details regarding the configuration and / or function of the spacer 50 are provided in U.S. Pat. Nos. 6,302,653 and 6,382,923, both of which are incorporated herein by reference.

[0069] In this embodiment, the spacer elements 50 are arranged in a sort of "stadium seating" configuration, whereby the spacer elements 50 are arranged in a concentric elliptical pattern, with the ends of the spacer elements 50 increasing in height from the bottom 181b of the inner wall the farther away from the center of the pumping chamber 181, forming a semi-elliptical dome-shaped region (shown by the dotted line in FIG. 4 ). Arranging the spacer elements 50 so that the ends of the spacer elements 50 form a semi-elliptical region that defines the dome-shaped region over which the pumping chamber portion 151 of the membrane 15 is intended to extend can allow for a desired volume of dead space that minimizes any reduction in the intended stroke volume of the pumping chamber 181. As shown in FIG. 3 (and FIG. 6 ), the "stadium seating" configuration in which the spacer elements 50 are arranged can include "passages" or breaks 50a in an elliptical pattern. The breaks (or passages) 50a help maintain an equal gas level throughout the rows (voids or dead spaces) 50b between the spacer elements 50 as fluid is delivered from the pumping chamber 181. For example, if the spacer elements 50 were arranged in the stadium seating configuration shown in FIG. 6 without breaks (or passages) 50A or other means for allowing liquid and air to flow between the spacer elements 50, the membrane 15 could bottom out on the spacer element 50 located at the outermost edge of the pump chamber 181, trapping any gas or liquid present in the gap between this outermost spacer element 50 and the side 181a of the pump chamber wall. Similarly, if the membrane 15 bottomed out on any two adjacent spacer elements 50, any gas and liquid in the gap between the elements 50 could be trapped. In such an arrangement, air or other gas in the center of the pump chamber 181 could be delivered at the end of the pump stroke, while liquid remained in the outer rows. Providing breaks (or passages) 50A or other fluid communication means between the gaps between the spacer elements 50 helps maintain equal gas levels throughout the gaps during the pump strobe, thereby preventing air or other gas from exiting the pump chamber 181 unless a substantial liquid volume has been delivered.

[0070] In some embodiments, the spacer elements 50 and / or membrane 15 can be arranged so that when membrane 15 is pressed into contact with gas spacers 50, it generally does not wrap around or otherwise deform around individual spacers 50 or otherwise extend significantly into the spaces between spacers 50. Such an arrangement can reduce any stretching or damage to membrane 15 caused by wrapping around or otherwise deforming around one or more individual spacer elements 50. For example, in this embodiment, it has also been found to be advantageous to size the gaps between the spacers 50 so that their width is approximately equal to the width of the gas spacer 50. This feature has been found to help prevent deformation of the membrane 15, such as sagging of the membrane into the gaps between the spacers 50, when the membrane 15 is forced into contact with the spacers 50 during pumping operations.

[0071] According to another aspect of the present invention, the interior wall of the pumping chamber 181 can define a space through which the pumping chamber portion 151 of the membrane 15 is intended to extend, e.g., a semi-elliptical or larger recess than the dome-shaped space. In such a case, one or more spacer elements 50 can be positioned below the dome-shaped region through which the membrane portion 151 is intended to extend, rather than extending into the dome-shaped region. In some cases, the ends of the spacer elements 50 can define the periphery of the dome-shaped region through which the membrane portion 151 is intended to extend. Positioning the spacer elements 50 outside or adjacent to the periphery of the dome-shaped region through which the membrane portion 151 is intended to extend can have several advantages. For example, positioning one or more spacer elements 50 outside or adjacent to the dome-shaped region through which the flexible member is intended to extend provides the dead space between the spacer and the membrane, as described above, while minimizing any reduction in the intended stroke volume of the pumping chamber 181.

[0072] It should be understood that the spacer elements 50 within the pump chambers, if present, can be arranged in any other suitable manner, as shown, for example, in FIG. 7 . The left pump chamber 181 in FIG. 7 includes spacers 50 arranged similarly to those in FIG. 6 , but with only one break or passage 50a extending vertically through approximately the center of the pump chamber 181. The spacers 50 can be arranged to define a concave shape similar to that of FIG. 6 (i.e., the tops of the spacers 50 can form the semi-elliptical shapes shown in FIGS. 3 and 4 ), or can be arranged in any other suitable manner, such as to form a spherical, box-like shape, etc. The right pump chamber 181 in FIG. 7 illustrates an embodiment in which the spacers 50 are arranged vertically and the gaps 50b between the spacers 50 are also arranged vertically. Similar to the left pump chamber, the spacers 50 in the right pump chamber 181 can define a semi-elliptical, spherical, box-like, or any other suitable shaped recess. However, it should be understood that the spacer elements 50 can have a fixed height, a different spatial pattern than that shown, etc.

[0073] Additionally, the membrane 15 itself may have other features in addition to or in place of the gas spacer elements or spacer elements 50, such as ribs, bulges, tabs, grooves, channels, etc. Such features in the membrane 15 may provide other features, such as helping to prevent the membrane 15 from sticking, etc., and / or helping to control how the sheet folds or otherwise deforms as it moves during a pumping action. For example, bulges or other features in the membrane 15 may help the sheet deform consistently and prevent it from folding in the same area during repeated cycles. Folding the membrane 15 in the same area during repeated cycles could cause the membrane 15 to prematurely fail in that fold area, and therefore features in the membrane 15 may help control how and where folds occur.

[0074] In this exemplary embodiment, the base member 18 of the cassette 24 defines a plurality of controllable valve features, fluid pathways, and other structures to guide fluid movement within the cassette 24. FIG. 6 shows a plan view of the pump chamber side of the base member 18, which is also seen in the perspective view of FIG. 3. FIG. 8 shows a perspective view of the back side of the base member 18. FIG. 9 shows a plan view of the back side of the base member 18. The tubes 156 of each of the ports 150, 152, and 154 are in fluid communication with respective valve wells or chambers 183 formed in the base member 18. The valve wells or chambers 183 are fluidly isolated from one another by walls surrounding each valve well or chamber 183 and by sealing engagement of the membrane 15 with the walls around the wells or chambers 183. Similarly, the valve well 185 can be sealed from the port 186 by operation of the cassette membrane 15. The pump inlet or outlet valves have wells 189, 194 that can be sealed from ports 190, 192 by manipulation of cassette membrane 15. As noted above, membrane 15 can sealingly engage walls around each valve well or chamber 183, 185, 189, and 194 (and other walls of base member 18), for example, by being pressed into contact with the walls when loaded into cycler 14. Fluid within valve wells or chambers 183, 185, 189, and 194 can flow into or out of each valve port or orifice 184, 186, 190, and 192 when membrane 15 is not pressed into sealing engagement with valve ports or orifices 184, 186, 190, and 192. Thus, each valve port or orifice 184, 186, 190, and 192 defines a valve (e.g., a "volcano valve") that can be opened and closed by selectively moving a portion of the membrane 15 associated with the valve port or orifice 184, 186, 190, and 192. The cassette valve port or orifice seat may be defined by a raised wall 196 to form a valve seat (see FIG. 3) so that occlusion of the port by the cassette membrane 15 and associated valve control region of the gasket is more reliably achieved.However, in other embodiments, the cassette valve port seats may not include raised walls 196 if the cassette membrane 15 is sufficiently flexible or appropriately shaped so that the applied pressure is sufficient to seal the valve ports 184, 186, 190 and 192 from the valves.

[0075] As will be described in more detail below, the cycler 14 can selectively control the position of portions of the membrane 15, thereby opening and closing valve ports (such as port 184) to control flow through various fluid channels and other pathways within the cassette 24. Flow through valve port 184 leads to the rear side of the base member 18. In the case of the valve ports associated with the heater bag and drain (ports 150 and 152), the valve port 184 leads to a common channel 200 formed in the rear side of the base member 18. As with the valve well 183 and chambers 183, 185, 189, and 194, the channel 200 is isolated from the other channels and pathways of the cassette 24 by the sheet 16, which provides sealing contact with the wall of the base member 18 that forms the channel 200. In the case of the valve port 184 associated with the patient line port 154, flow through port 184 leads to a common channel 202 in the rear side of the base member 18. The common channel 200 may also be referred to herein as an upper fluid bus, and the common channel 202 may also be referred to as a lower fluid bus.

[0076] Returning to FIG. 6 , each of the spikes 160 (shown without its cap in FIG. 6 ) is in fluid communication with a respective valve well 185, which are isolated from one another by the walls and sealing engagement of the membrane 15 with the walls forming the well 185. When the membrane 15 is not in sealing engagement with the port 186, fluid in the valve wells 185 can flow into the respective valve port 186. (Again, the position of the portion of the membrane 15 above each valve port 186 can be controlled by the cycler 14 to open or close the valve port 186.) Flow through the valve ports 186 leads to the back side of the base member 18 and into the common channel 202. Thus, according to one aspect of the invention, a cassette can have multiple solution supply lines (or other lines providing substances to provide dialysate) connected to a common manifold or channel of the cassette, and each line can have a corresponding valve controlling flow to or from the line to the common manifold or channel. Fluid in channel 202 can flow into lower openings 187 of pump chamber 181 by way of openings 188 that lead to lower pump valve wells 189 (see FIG. 6 ). When the respective portions of membrane 15 are not pressed into sealing engagement with ports 190, flow from lower pump valve wells 189 can pass through respective lower pump valve ports 190. As shown in FIG. 9 , lower pump valve ports 190 lead to channels that communicate with lower openings 187 of pump channel 181. Flow exiting pump chamber 181 can pass through upper openings 191 and into channels that communicate with upper valve ports 192. Flow from upper valve ports 192 (when membrane 15 is not sealingly engaged with ports 192) can enter respective upper valve wells 194 and into openings 193 that communicate with a common channel 200 on the rear side of base member 18.

[0077] As will be appreciated, cassette 24 can be controlled so that pump chamber 181 can pump fluid to or from any of ports 150, 152, and 154 and / or any of spikes 160. For example, fresh dialysate provided by one of containers 20 connected by line 30 to one of spikes 160 can be drawn into common channel 202 by opening the appropriate valve port 186 for the appropriate spike 160 (and, optionally, closing other valve ports 186 for other spikes). Also, lower pump valve port 190 can be opened and upper pump valve port 192 can be closed. The portion of the membrane 15 (i.e., pump diaphragm 151) associated with the pump chamber 181 can then be moved (e.g., away from the base member 18 and the pump chamber interior wall) to reduce the pressure within the pump chamber 181, thereby drawing fluid through the selected spike 160, through the corresponding valve port 186, into the common channel 181, through opening 188 into the lower pump valve well 189, through the (open) lower pump valve port 190, and through the lower opening 187 into the pump chamber 181. The valve ports 186 are independently operable, allowing the option to draw fluid through any one or combination of spikes 160 and associated source containers 20 in any desired order or simultaneously. Of course, only one pump chamber 181 need be operated to draw fluid. The other pump chambers can remain inoperable and sealed against flow by closing the appropriate lower pump valve ports 190.

[0078] Fluid in pump chamber 181 can close lower pump valve port 190 and open upper pump valve port 192. As membrane 15 moves towards base member 18, pressure in pump chamber 181 can increase, causing fluid in pump chamber 181 to pass through upper opening 191, through (open) upper pump valve port 192 into upper pump valve well 194, and through opening 193 into common channel 200. By opening the appropriate valve ports 184, fluid in the channels 200 can be directed to the heater bag ports 150 and / or drain ports 152 (and into the corresponding heater bag or drain lines). In this way, for example, fluid in one or more of the containers 20 can be pumped into the cassette 24 and out the heater bag 212 and / or drain.

[0079] Fluid within heater bag 22 (e.g., after being suitably heated on a heater tray for introduction into a patient's body) can be drawn into cassette 24 by opening valve port 184 for heater bag port 150, closing lower pump valve port 190, and opening upper pump valve port 192. By moving a portion of membrane 15 associated with pump chamber 181 away from base member 18, the pressure within pump chamber 181 can be reduced, causing fluid flow from heater bag 22 into pump chamber 181. With pump chamber 181 filled with heated fluid from heater bag 22, upper pump valve port 192 can be closed and lower pump valve port 190 can be opened. To deliver heated dialysate to the patient, valve port 184 for patient port 154 can be opened and valve port 186 for spike 160 can be closed. By moving the membrane in pump chamber 181 towards base member 18, the pressure in pump chamber 181 can be increased, causing fluid to flow through lower pump valve port 190, through opening 188 into common channel 202, and to and through (open) valve port 184 for patient port 154. This action can be repeated a suitable number of times to deliver the desired volume of heated dialysate to the patient.

[0080] To drain the patient, the valve port 184 for the patient port 154 can be opened, the upper pump valve port 192 can be closed, and the lower pump valve port 190 can be opened (with the spike valve port 186 closed). The membrane 15 can be moved to draw fluid from the patient port 154 into the pump chamber 181. The lower pump valve port 190 can then be closed, the upper valve port 192 can be opened, and the valve port 184 for the drain port 152 can be opened. Fluid from the pump chamber 181 can then be pumped into a drain line for disposal in a drain or collection container, or for sampling. Alternatively, fluid can be sent to one or more spikes 160 / lines 30 for sampling or drainage purposes. This operation can be repeated until enough dialysate has been removed from the patient and pumped to the drain.

[0081] The heater bag 22 can also serve as a mixing container. Depending on the predetermined treatment requirements for an individual patient, dialysate or other solutions having different compositions can be connected to the cassette 24 via suitable solution lines 30 and spike 160. Measured amounts of each solution can be added to the heater bag 22 using the cassette 24 and mixed according to one or more predetermined recipes stored in microprocessor memory and accessible to the control system 16. Alternatively, a user can input predetermined treatment parameters via the user interface 144. The control system 16 can be programmed to calculate the appropriate mixing requirements based on the type of dialysate or solution container connected to the spike 160, and the control system 16 can then control the mixing and delivery of the prescribed mixture to the patient.

[0082] According to aspects of the present invention, the pressure applied by the pump to the dialysate being infused into or removed from the patient can be controlled to minimize the patient's sensation of a "tug" or "pull" resulting from pressure fluctuations during drain and fill operations. For example, when draining dialysate, the suction pressure (or vacuum / negative pressure) can be reduced near the end of the drain process, thereby minimizing the patient's sensation of dialysate removal. A similar approach can be used near the end of the fill operation, i.e., the delivery pressure (or positive pressure) can be reduced near the end of the fill. If it is found that a patient is more sensitive to fluid shifts during different cycles of therapy, different pressure profiles can be used for different fill and / or drain cycles. For example, a relatively higher (or lower) pressure can be used during the fill and / or drain cycles when the patient is asleep compared to when the patient is awake. The cycler 14 may, for example, use an infrared motion detector to infer that the patient is asleep when their movement is reduced, or may use detected changes in blood pressure, brain waves, or other parameters indicative of sleep to detect the patient's sleep / wake state. Alternatively, the cycler 14 can simply "ask" the patient "Are you asleep?" and control system operation based on the patient's response (or lack thereof).

[0083] Patient Line Status Detector In one aspect, a patient line status detector detects when a fluid line to a patient, such as the patient line 34, is properly primed before connection to the patient. While fluid line status detection is described with respect to a patient line, it should be understood that aspects of the invention include detecting the presence of any suitable tubing segment or other conduit and / or the fill status of the tubing segment or other conduit. Accordingly, aspects of the invention are not limited to use with patient lines, as any suitable conduit and tubular detector can be used. In some embodiments, a fluid line status detector can be used to detect proper priming of a tubing segment at the patient connection end of a fluid line. The patient line 34 can be connected to an indwelling catheter within a patient's blood vessel, body cavity, subcutaneously, or another organ. In one embodiment, the patient line 34 can be a component of a peritoneal dialysis system 10, delivering and receiving dialysate to and from the patient's peritoneal cavity. The tubing segment near the distal end of the line can be placed in an upright position in a cradle in which the detector's sensor element is located.

[0084] FIG. 10 shows a front perspective view of an exemplary configuration of a fluid line condition detector 1000, which may be mounted or otherwise exposed on the left exterior side of the housing 82, e.g., to the left of the front door 141. For illustrative purposes, the fluid line condition detector will be described as a patient line condition detector 1000. The patient line 34 should preferably be primed before connection to the patient because, if not, air may be delivered into the patient's body, increasing the risk of complications. In some configurations, it may be acceptable for up to 1 mL of air to be present in the patient line 34 before connection to the patient's peritoneal dialysis catheter. The exemplary configurations of the patient line condition detector 1000 described below generally meet or exceed this criterion because they can detect the liquid level in a properly positioned tubing segment of the line 34, such that, after priming, at most approximately 0.2 mL of air remains at the tip of the line 34.

[0085] In one aspect, the patient line condition detector 1000 in a first configuration can include a base member 1002. There can also be a patient line condition detector housing 1006 attached to (or typically molded with) the base member 1002, such that the detector housing 1006 can extend outwardly from the base member 1002. The detector housing 1006 defines a tubing or connector-retaining channel 1012 within which the tubing segment 34a or its associated connector 36 near the distal end of the patient line 34 can be disposed. The portion of the detector housing 1006 facing the base member 1002 can be substantially hollow, thereby creating an open cavity 1008 (shown in FIGS. 11 and 13) at the rear of the detector housing 1006. The open cavity 1008 can accommodate placement and positioning of sensor elements (1026, 1028, 1030, and 1032 shown in FIG. 13) adjacent to the channel 1012 within which the tubing segment 34a can be disposed. In an alternative embodiment, there may also optionally be a stabilizing tab 1010 extending outwardly from the base member 1002. The stabilizing tab 1010 may have a concave outer shape that can substantially match the curvature of the patient line connector 36 when the patient line 34 is placed within the patient line condition detector housing 1006. The stabilizing tab 1010 may help prevent the connector 36 from moving during priming of the patient line 34, thereby improving the accuracy and efficiency of the priming process. The detector housing 1006 may have a shape that generally helps define a tubing or connector retaining channel 1012, which may further have dimensions that vary to accommodate the transition from the tubing segment 34a to the tubing connector 36.

[0086] In this exemplary embodiment, the channel 1012 can substantially conform to the shape of the patient line connector 36. As a result, the channel 1012 can be “U-shaped” to encompass a portion of the connector 36 when positioned within the channel 1012. The channel 1012 can be comprised of two separate features: a tubing portion 1014 and a cradle 1016. In another aspect, the tubing portion 1014 can be positioned below the cradle 1016. Additionally, the cradle 1016 can be formed by a pair of side walls 1018 and a rear wall 1020. Both of the side walls 1018 can be slightly convex in shape, while the rear wall 1020 can be generally flat or otherwise have a contour that generally matches the shape of the adjacent portion of the connector 36. The generally convex shape of the side walls 1018 helps to lock the patient line connector 36 in place when positioned within the cradle 1016.

[0087] In an exemplary embodiment for the first configuration of the patient line condition detector 1000, the region 36a of the patient line connector 36 can have a generally planar surface that can be fixedly positioned against an opposing rear wall 1020 of the channel 1012. Additionally, this region of the connector 36 can have a recess 37 on the opposite side, which can be positioned adjacent to an opposing side wall 1018 of the channel 1012 when the connector 36 is positioned within the detector housing 1006. The recess 37 can be defined by a raised element 37a located on the side of the connector 36. One of these recesses 37 is partially visible in FIG. 10 . The two side walls 1018 can have a generally mating shape (e.g., a convex shape, etc.) that engages the recess 37 and helps lock the connector 36 in place within the cradle 1016. This helps prevent the connector 36 and tubing segment 34a from being inadvertently removed from the detector housing 1006 during priming of the patient line 34. If the raised element 37a of the connector 36 is made from a sufficiently flexible material (e.g., polypropylene, polyethylene or other similar polymeric material), a threshold pulling force on the connector 36 can release the connector 36 and the tube segment 34a from the detector housing 1006.

[0088] In another aspect, the tube portion 1014 of the cavity 1012 can enclose most of the tube segment 34a just before the tube segment 34a is attached to the connector 36. The tube portion 1014 can accommodate most of the tube segment 34a using three structures: two side walls 1018 and a back wall 1020. In an embodiment, the two side walls 1018 and the back wall 1020 can be transparent or sufficiently translucent (e.g., constructed from Plexiglas) to allow light from multiple LEDs (e.g., LEDs 1028, 1030, and 1032 in FIG. 13 ) to be directed through the walls without being significantly obstructed or diffused. An optical sensor 1026 (shown in FIG. 12 ) can also be positioned along one of the walls 1018 and can detect light being emitted by the LEDs. In the illustrated embodiment, a clear or translucent plastic insert 1019 can be configured to snap into the main detector housing 1006 in the area where the LEDs are located within the housing.

[0089] FIG. 12 shows a perspective layout of the patient line status detector printed circuit board 1022 with LEDs 1028, 1030 and 1032 and optical sensor 1026 surface mounted thereon. 13 shows a top view of LEDs 1028, 1030, and 1032 and optical sensor 1026 mounted on a detector circuit board 1022, which may be positioned adjacent a rear wall 1020 and a side wall 1018 of the detector housing 1006. FIG. 14 is an exploded perspective view of the detection assembly 1000, showing the relative positions of the printed circuit board 1022 and translucent or transparent plastic insert 1019 with respect to the housing 1006.

[0090] 11 , the detector circuit board 1022 can be disposed over the support structure 1004 and the interior open cavity 1008, the interior open cavity 1008 being formed from a detector housing 1006 extending outward from a base member 1002. The base member 1002 and the support structure 1004 can be attached to, or typically molded to, one another such that the base member 1002 is generally perpendicular to the support structure 1004. This orientation generally allows the plane of the detector circuit board 1022 to be generally perpendicular to the longitudinal axis of the tube segment 34a when secured within the channel 1012. The detector circuit board 1022 can generally conform to the cross-sectional shape of the open cavity 1008 and can also have a cutout 1024 ( FIGS. 12 , 13 ) that generally conforms to the cross-sectional shape of the channel 1012 formed by the back wall 1020 and the side wall 1018 ( FIG. 10 ). A detector circuit board 1022 can then be placed within the open cavity 1008, with the cutouts 1024 generally adjacent to the rear wall 1020 and side wall 1018 of the detector housing 1006 to ensure proper alignment of the detector circuit board 1022 with the tube segment 34a or connector 36.

[0091] The detector circuit board 1022 can include a plurality of LEDs and at least one optical sensor that can be attached to the circuit board 1022; in one embodiment, the LEDs and optical sensor can be surface-mounted on the circuit board 1022. In one aspect, the detector circuit board 1022 can include a first LED 1028, a second LED 1030, a third LED 1032, and an optical sensor 1026. The first LED 1028 and the second LED 1030 can be positioned to direct light through the same sidewall 1018a of the channel 1012. The light emitted by the first LED 1028 and the second LED 1030 can be directed generally parallel and generally perpendicular to the sidewall 1018a to which they are closest. The optical sensor 1026 can be positioned along the opposing sidewall 1018b of the channel 1012. Additionally, a third LED 1032 can be positioned along the rear wall 1020 of the channel 1012. In this exemplary embodiment, this configuration of the LEDs and optical sensor 1026 enables the patient line status detector 1000 to detect three different states during the process of priming the patient line 34: the tubing segment 34a or connector 36 is nearly completely filled with fluid (primed state), the tubing segment 34a or connector 36 is not completely filled (unprimed state), or the tubing segment 34a and / or connector 36 is not present in the channel 1012 (line absent state).

[0092] When used in a peritoneal dialysis system, such as peritoneal dialysis system 10, detector circuit board 1022 configured in this manner can send appropriate control signals to PD cycler controller system 16. Controller system 16 can then notify a user via user interface 144 to position the distal end of line 34 at patient line status detector 1000 before connecting it to a peritoneal dialysis catheter. The controller can then monitor the placement of tubing segment 34a within patient line status detector 1000. The controller can then instruct the priming of line 34, indicate an end to priming once line 34 is primed, and then instruct the user to disconnect the distal end of line 34 from patient line status detector 1000 and connect it to the user's peritoneal dialysis catheter.

[0093] Surface mounting the LEDs 1028, 1030, and 1032 and the optical sensor 1026 to the circuit board 1022 can simplify the manufacturing process for the device, can allow the patient line status detector 1000 and circuit board 1022 to occupy a relatively small space, and can help eliminate errors that may result from movement of the LEDs or optical sensor relative to each other or to the channel 1012. Without surface mounting of the sensor components, misalignment of the components may occur during assembly of the device or during its use.

[0094] In one aspect, the optical axis (or central optical axis) of the LED 1032 can form an oblique angle with respect to the optical axis of the optical sensor 1026. In the illustrated embodiment, the optical axes of the first LED 1028, the second LED 103, and the optical sensor 1026 are each generally parallel to one another and to the rear wall 1020 of the channel 1012. Thus, the amount of light directed from the LEDs to the optical sensor 1026 can vary depending on (a) the presence or absence of a translucent or transparent conduit within the channel 1012 and / or (b) the presence of liquid within the conduit (which may be, for example, the tube segment 34a). Preferably, the LED 1032 can be positioned near the sidewall (e.g., 1018a) farthest from the optical sensor 1026 to refract a portion of the light emitted by the LED 1032 due to the presence of the translucent or transparent tube segment 34a within the channel 1012. The degree of refraction away from or toward the optical sensor 1026 can depend on the presence or absence of fluid in the tube segment 34a.

[0095] In various embodiments, the oblique angle of the LED 1032 relative to the optical sensor 1026 creates a more robust system for determining the presence or absence of liquid with translucent or transparent conduits in the channel 1012. The LED 1032 can be positioned so that its optical axis can form any angle between 91° and 179° with respect to the optical axis of the optical sensor 1026. Preferably, the angle can be set within a range of about 95° to about 135° with respect to the optical axis of the optical sensor. More preferably, the LED 1032 can be set to have an optical axis at about 115° ±5° with respect to the optical axis of the optical sensor. In the exemplary embodiment shown in FIG. 13, the angle θ of the LED 1032's optical axis relative to the optical axis of the optical sensor 1026 was set to approximately 115° ±5°. (The optical axis of the optical sensor 1026 in this particular embodiment is approximately parallel to the back wall 1020 and approximately perpendicular to the side wall 1018b.) The benefits of angling the LED 1032 with respect to the optical axis of the optical sensor 1026 were confirmed in a series of tests comparing the performance of the optical sensor 1026 in distinguishing fluid-filled tube segments (wet tubes) from air-filled tube segments (dry tubes) using an LED 1032 oriented at an angle of approximately 115° versus an LED whose optical axis was oriented perpendicular or parallel to the optical axis of the optical sensor 1026. The results showed that the angled LED-based system was more robust in distinguishing the presence or absence of liquid in the pipe segment 34a. By using the angled LED 1032, it was possible to select an optical sensor signal strength threshold above which an empty pipe segment 34a could be reliably detected. It was also possible to select an optical sensor signal strength threshold below which a fluid-filled pipe segment 34a could be reliably detected.

[0096] FIG. 15 shows a graph of test results demonstrating that the patient line condition detector 1000 can distinguish between a liquid-filled tubing segment 34a (primed condition) and an empty tubing segment 34a (unprimed condition). The results were recorded with the LED 1032 (third LED) oriented at an angle of approximately 115° relative to the optical axis of the optical sensor 1026 and the LED 1030 (second LED) oriented approximately parallel to the optical axis of the optical sensor 1026. The results plotted in FIG. 15 demonstrate that the patient line condition detector 1000 can reliably distinguish between primed and unprimed conditions. When the relative signal strength associated with the light received from the LED 1030 was approximately 0.4 or greater, the upper signal detection threshold 1027 and lower signal detection threshold 1029 for the unprimed condition versus the primed condition could be determined using only the light signal received from the LED 1032. An upper threshold 1027 can be used to identify an unprimed condition, and a lower threshold 1029 can be used to identify a primed condition. Data points that fall above the upper threshold 1027 are associated with an empty tubing segment 34a (an unprimed condition), and data points that fall below the lower threshold 1029 are associated with a fluid-filled tubing segment 34a (a primed condition). A relatively narrow region 1031 between these two thresholds defines a range of relative signal strengths associated with the light received from the LED 1032 within which an assessment of the primed condition of the tubing segment 34a may be uncertain. A controller (e.g., control system 16, etc.) can be programmed to send an appropriate message to a user whenever the signal strength associated with the light received from the LED 1032 falls within this uncertainty range. For example, the user can be instructed to evaluate whether the tubing segment 34a and / or connector 36 are properly attached to the patient line condition detector 1000. In the context of a peritoneal dialysis system, if the optical sensor 1026 generates a signal corresponding to an empty tubing segment 34a, the controller can instruct the cycler to continue priming the patient line 34 with dialysate.A signal corresponding to the liquid fill tubing segment 34a can be used by the controller to stop further priming and indicate to the user that the fluid line 34 is ready to be connected to a dialysis catheter.

[0097] In an embodiment, the cycler 14 controller can continuously monitor the received signal from one of the LEDs at the beginning of the priming procedure. Upon detecting a change in the received signal, the controller can stop further fluid pumping to allow for a complete measurement using all of the LEDs. If the received signal is sufficiently within the range indicating a wet tube, further priming can be stopped. However, if the received signal is within the uncertainty region 1031 or the "dry" region, the cycler commands a series of small, incremental pulses of fluid into the patient line via the pumping cassette, repeatedly reading the LED signal strength after each pulse of fluid. Primer can then be stopped as soon as a reading indicating a fluid-filled line is achieved at the sensor level. Incremental pulses of fluid can be achieved by commanding brief pulses of a valve connecting a pressure reservoir to the pump actuation chamber or control chamber. Alternatively, the controller can command continuous pressure application to the pump actuation chamber or control chamber and command the pump's outlet valve to briefly open and close to generate a series of fluid pulses.

[0098] FIG. 16 shows a graph of test results demonstrating the superiority of an angled LED 1032 (LEDc) compared to an LED (LEDd) whose optical axis is approximately perpendicular to the optical axis of the optical sensor 1026. In this case, the relative signal strength generated by the optical sensor 1026 in response to light from the LED was plotted against the signal strength associated with the light from the LED. Some separation between the liquid-filled (“primed”) and empty (“unprimed”) tube segments 34a was evident at an LED relative signal strength of approximately 0.015, but there remained a substantial number of “unprimed” data points 1035 that could not be distinguished from the “primed” data points based on this threshold. On the other hand, a relative signal strength 1033 associated with light from LEDc between 0.028 and 0.03 effectively distinguishes between the “primed” tube segment 34a (primed state) and the “unprimed” tube segment 34a (unprimed state). Therefore, the angled LED (1032) can produce more reliable data than an LED aimed at a right angle.

[0099] In another embodiment, the patient line status detector 1000 can also determine whether a tubing segment 34 a is present in the channel 1012. In one aspect, the first LED 1028 and the second LED 1030 can be positioned next to each other. One LED (e.g., LED 1028) can be positioned so that its optical axis passes through approximately the center of a properly positioned translucent or transparent conduit or tubing segment 34 a in the channel 1012. The second LED (e.g., LED 1030) can be positioned so that its optical axis is slightly shifted off-center relative to the conduit or tubing segment 34 a in the channel 1012. This pairing of centered / off-centered LEDs on one side of the channel 1012, with the optical sensor 1026 on the opposite side of the channel 1012, has been found to improve the reliability of determining the presence or absence of a fluid conduit or tubing segment 34 a in the channel 1012. In a series of tests in which the tube segment 34a was alternately absent, present but improperly positioned, or present and properly positioned within the channel 1012, signal measurements were taken from the first LED and the second LED 1030 by the optical sensor 1026. The signals received from each LED were plotted against each other, and the results are shown in FIG.

[0100] 17 , it was found that in the majority of cases when tube segment 34a was absent from channel 1012 (region 1039), the signal strength received by optical sensor 1026 due to LEDa (LEDa received strength) did not differ significantly from the signal strength received from LEDa during a calibration step in which LEDa was illuminated in the known absence of any tube in channel 1012. Similarly, it was found that the signal strength associated with LEDb (LEDb received strength) did not differ significantly from LEDb during a calibration step in which LEDb was illuminated in the known absence of any tube in channel 1012. Patient line status detector 1000 can reliably determine that no tube is present in channel 1012 when the ratio of LEDa to its calibrated value and the ratio of LEDb to its calibrated value are each approximately 1±20%. In a preferred embodiment, the threshold ratio may be set to 1±15%. In embodiments in which patient line status detector 1000 is used with a peritoneal dialysis cycler, the values ​​of LEDa and LEDb in region 1039 of FIG. 17 can be used to indicate, for example, the absence of tubing segment 34a in channel 1012. The cycler controller can be programmed to notify the user via user interface 144 that further pumping action should be paused and that proper positioning of the tip of the patient line 34 in patient line status detector 1000 is required.

[0101] The configuration and alignment of the three LEDs and optical sensor 1026 described above can generate the necessary data using translucent or transparent fluid conduits (e.g., tubing segment 34a) having a wide range of translucency. Further testing found that the patient line status detector 1000 could provide reliable data for distinguishing liquid from air in a fluid conduit, or the presence or absence of a fluid conduit, using samples of tubing having significantly different degrees of translucency. It was also able to provide reliable data regarding whether the PVC tubing being used was non-sterile or sterilized (e.g., sterilized with EtOX).

[0102] In certain embodiments, the fluid conduit or patient line 34 may be transparent or translucent to light in a first spectrum or multiple spectrums. The fluid conduit may also be opaque to light in a second spectrum or multiple spectrums. The LEDs used in the patient line status detector 1000 may be selected based on the light transmission characteristics of the fluid conduit. For example, a first LED may be selected to emit light in a first spectrum or at least one of multiple first spectrums. A second LED may be selected to emit light in a second spectrum or multiple spectrums. For example, the fluid conduit may be transparent or translucent to light in at least the infrared spectrum, but opaque to light in at least the ultraviolet spectrum. A first LED (e.g., LED 1030) may emit light in the infrared spectrum, while a second LED (e.g., LED 1028) may be selected to emit light in the ultraviolet spectrum. The optical sensor 1026 may sense light emitted from each LED, or multiple sensors may be included in the optical sensor 1026, one for each LED wavelength. Filters and the like may be included as part of the optical sensor 1026 to filter out undesired wavelengths of light. For example, trim (short-pass and long-pass) and band-pass filters may be used.

[0103] In embodiments in which the LED 1028 emits ultraviolet light and the LED 1030 emits infrared light, if no tubing is in the channel 1012, the optical sensor 1026 may sense light from both LEDs 1028, 1030. If a tubing (e.g., a patient line 34) is installed in the channel 1012, the light from the ultraviolet LED 1028 may be blocked by the presence of the tubing. The light from the infrared LED may be recorded by the optical sensor 1026 because the tubing may be translucent or transparent to that light spectrum. Thus, the control system 16 may declare a tubing present if the intensity of the light from the ultraviolet LED 1028 falls below a predefined threshold (which may be set to indicate that the light is completely or nearly completely obscured) and the light from the infrared-emitting LED 1030 exceeds at least a certain threshold. This may be further beneficial because the patient line status detector 1000 may be able to distinguish between tubing of the expected type or composition and undesirable or unauthorized tubing types. The patient line status detector 1000 may also have greater robustness in distinguishing between various scenarios. For example, the use of ultraviolet and infrared LEDs may assist the patient line status detector 1000 in determining whether foreign objects or detritus are present in place of improperly placed tubing. Thus, troubleshooting and prompts generated for display on the user interface may be streamlined, and the cycler 14 may provide a better patient experience. This may be particularly desirable as patients are getting ready for bed each night, and prolonged troubleshooting can result in lost sleep and frustration.

[0104] In some embodiments, by matching the light source to the characteristics of the tube, it may be possible to omit one of the LEDs 1028, 1030 used to detect the tube. The infrared-emitting LED 1030 may be omitted, and the control system 16 may monitor only the light from the ultraviolet-emitting LED being blocked (e.g., a decrease below some predefined threshold) to determine whether a tube is present or properly installed in the channel 1012.

[0105] Measurements obtained by the optical sensor 1026 from the LEDs 1028, 1030, and 1032 can be used as inputs to the patient line status detector algorithm to detect the status of the tubing segment 34a. Other than detecting a filled, empty, or absent tubing segment 34a, the results of the algorithm may be inconclusive, potentially indicating movement or improper positioning of the tubing segment 34a within the patient line status detector 1000, or potentially the presence of a foreign object within the channel 1012 of the patient line status detector 1000. Due to manufacturing variations, the output from the LEDs 1028, 1030, and 1032 and the sensitivity of the optical sensor 1026 may vary between different assemblies. Therefore, it may be advantageous to perform an initial calibration of the patient line status detector 1000. For example, the following procedure may be used to obtain calibration values ​​for the LEDs and sensors.

[0106] (1) Ensure that tubing segment 34a is not loaded into patient line status detector 1000. (2) The optical sensor 1026 is queried for the following four different states: (a) no LED is lit; (b) the first LED 1028 (LEDa) is lit; (c) the second LED 1030 (LEDb) is lit; and (d) the third LED 1032 (LEDc) is lit. (3) Subtract the "LED off" signal value from each of the other signal values ​​to obtain their environmentally corrected values, and store these three measurements as the "no tube" calibration values.

[0107] Once the calibration values ​​for the LEDs and sensors are obtained, the condition of the tubing segment 34a can be detected. In this exemplary embodiment, the patient line condition detector algorithm performs condition detection in the test as follows: (1) The optical sensor 1026 is queried for four different states: (a) no LED; (b) the first LED 1028 (LEDa) is on; (c) the second LED 1030 (LEDb) is on; and (d) the third LED 1032 (LEDc) is on. (2) Subtract the "LED off" value from each of the other values ​​to find their environmental correction values. (3) Calculate the relative LED values ​​by dividing the test values ​​associated with each LED by their corresponding calibration ("no tube") values.

[0108] result: If the environmentally corrected LEDa value is less than 0.10, there may be a foreign object in the detector or an indeterminate result may be reported to the user. If the environmentally corrected LEDa and LEDb values ​​are within ±15% of their respective stored calibrated (no tube) values, report to the user that no tube segment is present in the detector. - if the environmentally corrected LEDb value is greater than or equal to about 40% of its stored calibrated (no tube) value, (a) check the signal associated with LEDc, and (i) if the environmentally corrected signal associated with LEDc is greater than or equal to about 150% of its calibrated ("no tube") value, report to the user that the tube segment is empty; (ii) if the environmentally corrected signal associated with LEDc is less than or equal to about 125% of its calibrated ("no tube") value, report to the user that the tube segment is filled with liquid; (iii) otherwise, report to the user that the result is inconclusive and that the measurement should be repeated (e.g., the tube segment may be moving, may be uneven, or is unclear, or that the tube segment should be checked to ensure it is properly inserted into the detector). If the environmentally corrected LEDb value is less than about 40% of its stored calibration ("no tube") value, the LEDc threshold for determining the presence of a dry tube may be larger. In one embodiment, for example, it has been empirically found that the LEDc empty tube threshold follows the relationship: [LEDc empty tube threshold] = -3.75 x [LEDb value] + 3.

[0109] Once it is determined that tubing segment 34a is loaded into the patient line status detector 1000, the patient line status detector algorithm may: a) query the optical sensor 1026 for an LED off and store this as a LED off value. b) Illuminate LEDc. c) Query the optical sensor 1026 and subtract the no-LED value from the LEDc value and store this as the initial value. d) Begin pumping. e) Query the optical sensor 1026 and subtract the no-LED value from the next LEDc value. f) If this value is less than 75% of the initial value, declare tubing segment 34a filled with liquid, reduce pumping, check detector status using the procedure above, and when prompted, report priming complete to the user. If not, continue to repeat the query, calculation, and comparison. In one embodiment, the system controller can be programmed to perform the query protocol as frequently as desired, for example, every 0.005 to 0.01 seconds. In an embodiment, the entire query cycle can conveniently occur every 0.5 seconds.

[0110] Figure 18 shows the results of a sample calibration procedure for six cycles. It is noted that the signal intensity range that distinguishes dry tubes from wet tubes (the "wet / dry threshold" range) varies between different cycles. (Variations in these ranges may be due to slight variations in manufacturing, assembly, and positioning of various components.) Thus, during calibration, each cycler can be assigned a wet / dry threshold signal intensity range that optimally separates data points generated by dry tubes from data points generated by wet tubes.

[0111] In some examples, the threshold at which control system 16 can register a wet or liquid-filled tubing may vary. For example, in some embodiments, as shown in FIG. 19 , the threshold may depend on a value previously collected when tubing segment 34 a was determined to be dry. This may help patient line condition detector 1000 more reliably determine when a transition from a dry line to a primed line occurs. Additionally, this may help make patient line condition detector 1000 more resistant to drift that may occur after repeated use and over time.

[0112] FIG. 19 shows a flowchart 1050 detailing several actions that may be performed to prime a fluid line. As shown, in block 1052, a user may power on the cycler 14 and begin preparing for treatment. If the patient line status detector 1000 is not empty in block 1054, the control system 16 of the cycler 14 may enter a troubleshooting mode in block 1056. During troubleshooting, the control system 16 of the cycler 14 may generate one or more messages or warnings for display on the user interface of the cycler 14 suggesting actions the user can take to resolve the problem. The user may be requested, for example, to remove an old line, clean the patient line status detector 1000, or check for detritus. If the patient line status detector 1000 is empty in block 1054, the user may load a patient line into the patient line status detector 1000 in block 1058. The cycler 14 may display a prompt instructing the user to do so. The control system 16 can use the patient line status detector 1000 to determine whether the patient line status detector 1000 is empty, as described elsewhere herein.

[0113] The control system 16 of the cycler 14 can coordinate the collection of status readings on the patient line 34 using the patient line status detector 1000 in block 1060. To collect these readings, the control system 16 can, for example, turn on the LED 1032 and check the light intensity using the optical sensor 1026. If the readings in block 1062 indicate that the patient line is not dry, the control system 16 of the cycler 14 can proceed to troubleshooting in block 1056. During troubleshooting, the control system 16 of the cycler 14 can generate one or more messages, alerts, or warnings for display on the user interface of the cycler 14 suggesting actions the user can take to resolve the problem. For example, the user may be asked to remove and reload the line. If the patient line status detector 1000 continues to determine that a wet line is present, treatment with the set 12 can be prohibited. The user may be asked to discard the set 12 and restart with a new set 12. During troubleshooting, various guidance graphics can be generated for display on the user interface.

[0114] If the ratio of the reading to the "no tube" calibration value matches a predefined range or threshold, the reading may be determined to indicate that the line is dry. In block 1062, if the reading indicates that the line is dry, the control system 16 may check the characteristics of that reading against one or more criteria. For example, in the embodiment shown in FIG. 19, the control system 16 may check whether the ratio of the reading to the "no tube" value is greater than a threshold value (e.g., 1.7). The control system 16 may also check whether that ratio is the highest seen on that patient line. In block 1062, if the reading (or ratio) is the highest ever, it may be saved as a maximum value in block 1068. Alternatively, if the reading (or ratio) is less than or equal to the threshold value (e.g., 1.7), the maximum value may be saved as the threshold value in block 1068.

[0115] In some embodiments, control system 16 may require multiple readings (e.g., consecutive readings) indicating the patient line is dry before instructing cycler 14 to prime the patient line. If the predefined number of checks has not been completed in block 1070, control system 16 may return to block 1060 to collect another reading. If the prerequisite number of checks has been completed in block 1070, control system 16 of cycler 14 may calculate a primed patient line threshold in block 1072. In alternative embodiments, this primed tube threshold may be calculated at a different point in time, for example, after the initial reading in block 1060. In such embodiments, the primed tube threshold may be updated with each subsequent pass through block 1060.

[0116] 19, the primed line threshold may be based on the maximum value stored in block 1068. In certain examples, the primed tube threshold may be calculated as the greater of a predefined value (e.g., 1.7) and the output of a predefined equation. For example, an equation using a constant added to a percentage of the maximum value from block 1068 may be used. In certain embodiments, the equation may be Primed Tube Threshold = 1.1 + (Max Dry Tube [from block 1068] * 0.2).

[0117] In block 1074, the control system 16 of the cycler 14 can command the cycler 14 to pump fluid through the patient line 34. In block 1076, the control system 16 of the cycler 14 can command readings to be collected by the patient line status detector 1000. If the readings indicate that the primed tubing threshold has not been breached in block 1078, the control system 16 of the cycler 14 can return to block 1074 and command additional pumping. Alternatively, readings can be collected while pumping is occurring. If the readings indicate that the primed tubing threshold has been breached in block 1078, the control system 16 of the cycler 14 can declare the line primed in block 1080. The control system 16 of the cycler 14 can also coordinate communication to the user (e.g., via a screen or prompt generated on the user interface) to instruct the user to proceed to the next step in treatment setup in block 1080. The reading may be determined to indicate a threshold breach when the ratio of the reading to the "no tube" value is greater than the primed tube threshold calculated in block 1072.

[0118] In some embodiments, the control system 16 of the cycler 14 can limit the volume of fluid allowed to be displaced during priming of the patient line 34. For example, there may be a volume threshold imposed on the volume displaced to prime the patient line 24 (e.g., the line volume at the nominal patient line 34), and the control system 16 can generate a notification or alert when this volume is breached. The user may be instructed (via the GUI) to check the line to ensure it is not fully primed and properly seated in the patient line status detector 1000. The control system 16 of the cycler 14 may allow the cycler 14 to return to block 1074 and continue priming upon receiving user input that the line is properly seated and not fully primed. In some embodiments, there may be an upper limit on the number of times continuous pumping is allowed. If this limit is reached or exceeded, the control system 16 of the cycler 14 can trigger an alert or error and prevent the cycler 14 from performing therapy in that set 12.

[0119] 20 shows a perspective view of a second configuration of patient line condition detector 1000. Two or more different patient line condition detector configurations may be required to accommodate various types of patient line connectors. In this exemplary embodiment, patient line condition detector 1000 in the second configuration may include most of the same components as patient line condition detector 1000 in the first configuration. However, to accommodate the different type of connector, the second configuration may include a raised element 1036 above housing 1006 rather than the stabilizing tab 1010 found on patient line condition detector 1000 in the first configuration. Raised element 1036 may generally conform to the shape of a standard patient line connector cap or connector flange.

[0120] According to aspects of the present disclosure, the detector housing 1006 may not include the tubing portion 1014. Thus, the open cavity 1008 may be positioned to allow for placement of the detector circuit board 1022 so that the LED and optical sensor may be located next to the translucent or transparent patient line connector 36 rather than as part of the tubing. Thus, the channel 1012 may be different shapes to accommodate transmission of the LED light through the connector 36.

[0121] In some embodiments, fluid line detector 1000 is not used to detect the priming status of a segment of tubing, but rather can simply use one or more LEDs to detect the presence of a line segment in fluid line detector 1000. The presence and proper placement of a line segment can be determined using fewer LEDs than in the embodiments described above.

[0122] In other embodiments, other types of sensors may be used to detect one or more conditions of interest associated with a fluid line, such as fluid line 30 or patient line 34 . For example, the fluid line detector 1000 may include a physically actuated switch, such as an electrical or magnetic contact switch or a microswitch. The fluid line detector 1000 may detect the presence of the fluid line connector 36 or tubing segment 34a through activation of such a switch. In some embodiments, two or more such switches may be used in the fluid line detector 1000, which may provide some redundancy or may be used to detect proper installation of multiple line segments of interest. In embodiments, for example, a microswitch may be located in the channel 1012 so that it is activated when the tubing segment 34a is placed in the channel 1012. Alternatively or additionally, a microswitch may be located in the cradle 1016, for example, so that it is activated when the fluid line connector 36 is placed in the fluid line detector 1000. In such embodiments, the cycler controller (e.g., control system 16) may not allow priming of the tubing until all of the one or more switches indicate that the line and / or connector are properly installed in the fluid line detector 1000.

[0123] In another embodiment, the fluid line detector 1000 can detect the presence and condition of a tube segment using a split-ring resonator-based sensor. Such a detector is shown and described, for example, in U.S. patent application Ser. No. 14 / 341,207, filed July 25, 2014, and entitled "System, Method and Apparatus for Bubble Detection in a Fluid Line Using a Split-Ring Resonator," the contents of which are incorporated herein by reference.

[0124] In some embodiments, the sensors of the fluid line detector 1000 can be configured to detect the type of fluid line 34 installed in the fluid line detector 1000 (e.g., adult size vs. pediatric size, opaque vs. translucent, etc.). The fluid line connector 36 and / or tubing segment 34a can have different distinguishing features (e.g., different geometric shapes), for example, depending on the type of line being used. The sensors of the fluid line detector 1000 can be configured to recognize what type of line is present based on detecting the presence or absence of such distinguishing features.

[0125] For example, if the fluid line detector 1000 is configured to use microswitches, the switches can be configured to detect the presence of a particular type of fluid line connector 36. The fluid line connectors 36 for each type of line can include different features (e.g., different protrusions or voids, or differently positioned protrusions or voids). When installed in the fluid line detector 1000, the fluid line connectors 36 can activate a predetermined switch or group of switches to detect the presence of a particular type of fluid line connector 36. If an invalid or unexpected combination of switches is activated, or if a combination of switches that does not correspond to the fluid line geometry intended for use with the cycler or medical device is activated, the controller can be programmed to notify the user of an incompatible or improper line. This arrangement of switches can also be used to detect improperly installed lines or connectors.

[0126] In other embodiments, completion of liquid priming of fluid line 34 can be inferred by detecting when liquid flow replaces air flow within the lumen at the distal end of line 34 or within connector 36 at the distal end of line 34. By monitoring the flow rate of the liquid under a predetermined force (either by gravity or active pumping), the difference in resistance to flow between air and liquid within a lumen of a given internal diameter can be detected. The internal diameter of the lumen can be selected to optimize discrimination between air and liquid flow. In most cases, this involves introducing a flow restriction near or at the end of the fluid line 34 or the distal connector. A properly selected flow restriction in the line 34 or distal end of the connector 36 allows relatively unrestricted air flow out of the line 34 while impeding liquid flow sufficiently to slow the progress of the liquid column through the line 34. This increased liquid flow resistance or change in pressure drop across the restriction zone can be detected using a flow meter in the liquid flow path or by measuring the change in volume of liquid in the upstream pump chamber over a predetermined time interval. In embodiments in which a membrane-based positive displacement pump is used, the rate of change in liquid volume in the pump chamber can be calculated by monitoring the pressure in the pump's working chamber (e.g., by applying Boyle's Law or other pressure-volume relationship for an ideal gas in a closed space), and the pressure in the working chamber indicates the pressure in the pump chamber of the pump. A controller, which receives liquid flow data from the fluid line or calculates the liquid flow out of the pump chamber by measuring the pressure change in the pump chamber, can compare the liquid flow to a predetermined value. Alternatively, the controller can calculate the drop in liquid flow rate and compare the change in flow rate to a prediction to declare the fluid line primed with liquid.

[0127] The zone of obstructed flow can include a narrowing, obstruction, partial blockage, or restriction (e.g., an orifice) that allows the easy passage of air but prevents the passage of liquid, such as dialysate. The feature can include a short segment of the tip tubing or fluid connector 36 that includes an area having a cross-sectional area smaller than the cross-sectional area of ​​the fluid conduit in the proximal section of the fluid line. As used herein, "restriction" is intended to encompass any feature that differentiates between air and liquid in a fluid conduit, increasing resistance to flow.

[0128] In embodiments, the restriction may be removable from the tip of the fluid line or associated connector. For example, the restriction may be included in a plug or cap that remains in place on the fluid line 34 during priming of the fluid line 34. The restriction may be molded into the plug or cap during manufacturing, for example. The restriction may be a recess, void, channel, or other flow path in the plug portion of the cap. The plug portion of the cap may be inserted directly into the fluid conduit or into the lumen of the attached connector 36. Alternatively, the plug or plug portion of the cap may be sized to have a diameter smaller than the diameter of the fluid conduit or associated connector lumen. When the cap is installed, the plug portion occludes a portion of the fluid conduit, providing a small gap between the outer surface of the plug and the inner wall of the conduit, thereby creating a restriction.

[0129] When fluid is pumped to prime the fluid line 34, the fluid moves at a relatively high flow rate as air is free to displace out of the fluid line 34 through the restriction. The increased impedance as the liquid reaches the restriction slows the flow rate. The flow rate can be monitored by a controller receiving input from one or more sensors as priming occurs. If the flow rate drops, it can be inferred that air is being forced out of the line beyond the restriction and that a given applied force is now forcing the liquid through the restriction. In some embodiments, the controller can employ additional logic to distinguish between multiple possible causes for reduced liquid flow in the fluid line.

[0130] In embodiments where the restriction is an orifice (located at the tip of a fluid line or in an attached connector), the cross-sectional area of ​​the orifice opening can be selected to create a desired amount of impedance to liquid flow. Additionally, the pumping pressure selected can be selected so that the flow rate when pumping air is detectably different from the flow rate when pumping liquid.

[0131] It may be desirable to place the restriction slightly upstream of the point at which the fluid line 34 is fully primed. This allows some fluid to flow through the restriction during the determination or recognition period when the controller is determining whether the impedance to fluid flow has changed. The line volume downstream from the restriction provides a fluid buffer to accommodate additional fluid while the controller makes the priming decision and stops the fluid pump, thus helping to prevent overflow of fluid out the distal end of the fluid line. Preferably, the pumping system's delay characteristics in response to changes in fluid flow impedance are empirically determined for the system once system parameters are selected. These parameters may include, for example, the force or pressure applied by the pump, the frequency of pumped volume determinations or flow rate measurements, the inner diameter and length of the tubing, the characteristics of the flow restriction, and the response times of the controller and pump. Once the system characteristics are determined, the post-restriction tubing or connector buffer volume required to prevent overflow can be empirically determined. For illustrative purposes, if the flow rate through the restriction is 30 mL / min and it takes about 5 seconds for the controller and pump to recognize and respond to the impedance change, then a hysteresis fluid volume of about 2.5 mL will be displaced while the system responds to the impedance change. In such an embodiment, the downstream volume beyond the restriction can be set to approximately 2.5 mL, or slightly more than 2.5 mL. This can serve to help minimize the amount of air remaining in the fluid line 34 during priming, without overpriming the line and causing fluid to overflow and leak down the line.

[0132] Alternatively, the restriction can extend along the line axis a distance that allows the restricted flow path volume to approach the expected flow rate while the impedance change is detected. This embodiment may be desirable when the restriction is contained within a fluid line cap.

[0133] In some embodiments, a material that is air-permeable but substantially liquid-impermeable can be used to restrict liquid flow. Such a material can allow relatively unrestricted air passage but restrict or prevent liquid passage. This material can be placed at the end of the fluid line 34, allowing air to be pumped through the line 34 but preventing overflow and spillage when the line 34 reaches a primed state. The material can then be removed along with the fluid line cap, for example, when a user removes the line cap. In some specific embodiments, the material used can be Goretex or another similar material (e.g., a breathable material that can be either microporous or macroporous). As described above, a drop in flow rate when the liquid reaches the material signals that the fluid line 34 has reached a primed state.

[0134] 21 and 22 show exemplary embodiments of a fluid line cap 5320, a fluid line 34, and a fluid line connector 36. As shown, a restriction 5322 is included within the fluid line 34. In other examples, the cap 5320 can have interior surface features incorporating a restriction similar to the restriction 5322 shown. In this example, the restriction 5322 is optionally positioned such that there is some fluid line 34 volume downstream of the restriction 5322. The restriction 5322 in the example embodiment is a portion of the fluid path with a reduced cross-sectional area. In other examples, the restriction 5322 can be an orifice or membrane that has one or more pores that have been cut, perforated, or otherwise increased resistance to the passage of liquid.

[0135] As shown in FIG. 21 , the liquid 5324 in the fluid line 34 has not yet reached the restriction 5322. At this point, the flow rate of fluid (e.g., a laminar column of air and liquid) through the fluid line 34 may be relatively high. As the air column is expelled, the liquid 5324 in the fluid line 34 will reach the restriction 5322. At this point, the flow rate will decrease due to a change in impedance. When the cycler determines that the impedance has changed, some liquid 5324 continues to flow. Once detected, the cycler can be programmed to stop the flow of liquid through the line. At this point, as shown in FIG. 22 , the liquid 5324 has substantially primed the entire line 34, including the volume of the line 34 downstream of the restriction 5322. The controller can be programmed to notify the user that the line 34 is primed and ready to be connected to a catheter or other device in preparation for treatment.

[0136] 23 and 24 illustrate another embodiment of a fluid line 34, a fluid line connector 36, and a fluid line cap 5320. As shown, there is no restriction on the fluid line 34 or the fluid line connector 36. The fluid line cap 5320 acts as a plug for the fluid line 34 and includes a restriction 5322. In an example embodiment, the restriction 5322 may include a notch, groove, or channel recessed around the plug portion of the fluid line cap 5320. The restriction 5322 may be sized to allow air to be pumped out of the line with relatively little resistance during priming, but to prevent liquid flow once the air column is fully released. Once the controller determines that the line 34 is primed, it may then instruct the user to remove the line cap 5320 and attach the fluid line connector 36 to an indwelling catheter or other similar device.

[0137] As shown in FIG. 23 , the liquid 5324 in the fluid line 34 has not yet reached the restriction 5322. At this point, the flow rate of fluid (gas plus liquid) through the fluid line 34 may be relatively high. When the liquid 5324 in the fluid line 34 reaches the restriction 5322, the flow rate decreases due to the change in impedance between the gas flow and the liquid flow through the restriction 5322. When the controller determines that the impedance has changed, some liquid 5324 continues to flow. Once detected, the controller stops the flow of liquid 5324 through the line. At this point, as shown in FIG. 24 , the liquid 5324 has substantially primed the entire line 34. The controller can then notify the user that the line 34 is primed and the line cap 5320 can be removed. Once the cap 5320 is removed, any excess pumped liquid 5324 can fill the volume of the fluid line 34 previously occupied by the plug portion of the fluid line cap 5320. Alternatively, the controller can be programmed to receive a signal from the user that the cap 5320 has been removed, and to cause the cycler or pump to advance a small amount of liquid down the liquid line 34 to top up the tip of the line 34 or connector 36 prior to use.

[0138] 25 shows a representative example of a fluid line cap 5320 with a plug or plug portion 5500. As shown, the fluid line cap 5320 includes a plug portion 5500 that can be sized to protrude into and fit snugly within a fluid conduit of a fluid line 34. A notch is provided in the plug portion 5500 of the fluid line cap 5320, which serves to create a restriction 5322 when the fluid line cap 5320 is installed on the end of a fluid line 34 or line connector 36. In the illustration, the notch is substantially triangular in cross section. In other embodiments, any suitable cross-sectional shape can be used. For example, other configurations can be used, such as a narrow lumen running the length of the plug 5500 while the remainder is solid. Also, as shown in FIG. 25, the end of the plug portion 5500 that extends into the fluid flow path can optionally be rounded (or tapered). This can facilitate placement of the fluid line cap 5320 onto the fluid line 34.

[0139] FIG. 26 illustrates another embodiment of a fluid line cap 5320. Similar to FIG. 25, the fluid line cap 5320 includes a bung portion 5500, which may be sized to protrude into and fit snugly within the fluid conduit of the fluid line 34. The restriction 5322 in FIG. 26 is a flow path that allows fluid to flow from the fluid conduit of the fluid line 34, through the interior of the bung portion 5500, and into the interior volume of the fluid line connector 36. FIG. 27 illustrates a cross-sectional view of the example fluid line cap 5320 taken along a longitudinal plane. The cross-sectional area of ​​the flow path is smaller than the cross-sectional area of ​​the fluid conduit of the fluid line 34.

[0140] FIG. 28 illustrates another embodiment of a fluid line cap 5320 installed in a fluid line connector 36 of a fluid line 34. As shown in FIG. 29, a cross section taken along line 28-28 in FIG. 28, the fluid line connector 36 includes a segment extending into a fluid conduit of the fluid line 34. The tubing of the fluid line 34 may be secured (e.g., glued, bonded, welded, etc.) to the fluid line connector 36. The fluid line connector 36 includes a fluid flow path leading from the fluid conduit of the fluid line 34 to a connector fitting 5502 included as part of the fluid line connector 36. The connector fitting 5502 may mate with cooperating features of a complementary connector (e.g., of a patient's indwelling catheter) to allow fluid to be delivered and / or withdrawn from a site (e.g., the peritoneal cavity or another body cavity). While a luer lock is shown in the example embodiment, any of a number of other suitable connectors or fittings may be used.

[0141] The cap in the example embodiment includes a plug portion 5500. The plug portion 5500 is sized to extend into the fluid path of the fluid line connector 36. In the example embodiment, the diameter of the plug portion 5500 is smaller than the diameter of the flow path in the fluid line connector 36. When the plug portion 5500 of the fluid line cap 5320 is installed in the flow path of the fluid line connector 36, a small gap remains between the outer surface of the plug portion 5500 and the inner wall of the flow path. Thus, the plug portion 5500 serves to reduce the cross-sectional area of ​​the flow path, creating a restriction 5322.

[0142] As mentioned above, in some embodiments, a small gap between the outer surface of the plug portion 5500 and the inner wall of the flow path need not exist. Instead, the plug portion 5500 can fit snugly into the flow path. The outer surface of the plug portion 5500 can be recessed with a notch to reduce the cross-sectional area of ​​the flow path and create a restriction, or an otherwise solid plug inserted into the connector lumen can include a narrow flow path to create a restricted flow path.

[0143] In one aspect, changes in flow path impedance can be determined based on flow rate estimates during the course of a pumping stroke from the pump cassette. Additionally, stroke volume estimates can be used to distinguish between changes in flow rate due to the pump chamber being empty and changes in flow rate due to liquid 5324 reaching a restriction 5322 in fluid line 34. Estimating flow rate and stroke volume during a pumping stroke is discussed further below.

[0144] In some embodiments, a controller algorithm that estimates stroke volume can be used to stop the stroke before the entire chamber is delivered to the fluid line. That is, the controller can be programmed to instruct the pump to perform a partial delivery stroke during priming to avoid reaching the pump diaphragm gas end-of-stroke. This can help ensure that any reduction in flow rate is not due to the pump diaphragm reaching a rigid pump chamber wall at the end of the pump stroke. When the controller determines that the volume of fluid pumped per unit time has decreased beyond a predetermined threshold, the liquid 5324 in the fluid line 34 can be assumed to have reached the restriction 5322, and the line can be considered primed.

[0145] In other embodiments, the controller can instruct the pump to pump fluid until a discontinuity in flow rate is detected. At that point, the controller can instruct the pumping device (e.g., a cycler) to attempt to deliver a small amount of fluid from another pump chamber of a dual-pump cassette. If the flow discontinuity is due to the pump diaphragm reaching the end of gas stroke, the flow from the other chamber should be greater than the ending flow rate from the first chamber. If the discontinuity is due to a primed line condition, the flow rate from the other chamber will be similar to the ending flow rate from the first chamber. Thus, the device controller can determine that the line is primed.

[0146] In some embodiments, a nominal internal tubing volume for the fluid line 34 can be determined. The controller can then direct the pump to move fluid down the line 34 until the volume of fluid primed down the line 34 is within one chamber volume of the nominal tubing volume. If the remaining volume in the line 34 is determined to be less than the volume of a full pump stroke, the controller can register the next flow discontinuity as indicating a primed condition.

[0147] The nominal internal volume of the line 34 can be determined based on the type of set being used. For example, a pediatric set can have a smaller internal tubing volume than an adult set. In some embodiments, the device controller can determine this information via an optical sensor. In some embodiments, the set can include a barcode or data matrix that can be read by a camera on the pumping device or cycler, and the encoded information allows the controller to determine the type of set installed. The controller receiving input from the camera may also be able to detect different features or geometries of parts of the set. For example, the fluid line connector 36 can have a unique detectable geometry that can be detected by the fluid line detector 1000, as described above. Alternatively, the user can manually enter information regarding the type of tubing or pump cassette being used in a user interface on the pumping device.

[0148] Line Priming Line Priming: To reduce the time required to prime a line, it may be preferable for a pumping device to actively prime the line rather than allowing gravity-based flow to accomplish the task. In gravity-based priming, which is the standard procedure, fluid flow through the line is determined by the head height of the reservoir in which the priming fluid is stored. The rate of fluid flow through the line during priming increases as the head height of the priming fluid reservoir increases. Actively priming the line using one or more pumps allows the pumping device or cycler to simulate various head heights relative to the reservoir while the reservoir remains in a fixed position. If the fluid pump includes a pneumatically driven pump chamber, the amount of air pressure applied to the pump chamber via a membrane can control the flow rate to a desired value without repositioning the priming reservoir. Eliminating the need to reposition the fluid reservoir helps keep the pumping or dialysis system compact, reduces setup burden for the user, and allows for relatively fast priming of the fluid line.

[0149] In some embodiments where the flow paths and chambers of the pump cassette are to be primed with fluid, priming can occur in two or more stages. The first stage can prime the lines at a lower effective head height (e.g., at low pump pressure or by passive gravity flow) than the second or subsequent stages. Turbulent flow at relatively high flow rates can result in air bubbles or pockets being introduced or trapped in various locations or recesses of the pump cassette. This problem can be mitigated by allowing the pump cassette to prime slowly, followed by a more rapid priming process once the fluid reaches the fluid lines downstream of the cassette. The length of the first stage can be empirically determined in advance through testing or by measuring the amount of fluid volume transferred from the priming reservoir to the cassette or attached fluid lines.

[0150] Reducing air bubble formation or entrapment is desirable for several reasons, including the ability of a line priming sensor to detect air bubbles and direct the controller to stop the process and issue a user warning.

[0151] The duration of the first priming stage may depend on the type of cassette being used (number of pumps and valves, complexity of the flow paths) and the volume of its internal fluid paths and pump chambers. Preferably, priming is performed at a flow rate slow enough to allow the fluid to displace air from the cassette from bottom to top and to ensure that most or all of the trapped air is forced into the attached fluid lines and then released to the atmosphere.

[0152] FIG. 30 shows a flowchart detailing steps by which a controller can be used to control the priming of a cassette and attached lines using two stages. In the example, the line being primed is a patient line extending from the pump cassette to the patient. The steps shown can be easily generalized to the priming of other fluid lines. As shown, in step 5570, the cycler begins priming the patient line by gravity feeding fluid through the cassette and into the line. In the example embodiment, the priming reservoir is a heater bag. Free flow can be achieved by controlling the valves on the cassette to create an open flow path between the patient line and the heater bag.

[0153] Upon initiating the priming operation in step 5570, the controller may start a timer for the first priming stage. The duration of the first priming stage may be empirically determined through testing to be sufficient to ensure that any air within the cassette has exited the cassette and flowed into the patient line. Using the example cassette shown in FIG. 3, this duration may range from 1 second to 3 seconds. In one embodiment, the timer may be set for approximately 1.6 seconds. In control system embodiments that do not use a timer but instead use a transition from the first priming stage when a predetermined volume of fluid has been delivered from the priming reservoir, the predetermined volume may be approximately 1 ml to 3 ml, considering the example cassette shown in FIG. 3.

[0154] When the timer has elapsed (or the predetermined volume has been delivered), the pumping device or cycler can proceed to step 5572 and begin actively priming the line. Preferably, step 5572 primes the line at a faster flow rate than step 5570. The cycler can continue actively priming the patient line until the priming sensor indicates that the line has reached a fully primed state. In some embodiments, the controller can then notify the user in a user interface that priming is complete and the primed line is ready to be connected.

[0155] Set Loading and Operation FIG. 31 (37) shows a perspective view of the APD system 10 of FIG. 1A with the door 141 of the cycler 14 lowered to an open position, exposing a mounting location 145 for the cassette 24 and a carriage 146 for the solution line 30. (In this embodiment, the door 141 is attached to the cycler housing 82 by a hinge at the bottom of the door 141.) When loading the set 12, the cassette 24 is placed in the mounting location 145 with the membrane 15 and the pump chamber side of the cassette 24 facing upward, and the portions of the membrane 15 associated with the pump chamber and valve ports can interact with a control surface 148 of the cycler 14 when the door 141 is closed. The mounting location 145 can be shaped to match the shape of the base member 18, thereby ensuring proper orientation of the cassette 24 in the mounting location 145. In this exemplary embodiment, cassette 24 and mounting location 145 have a generally rectangular shape that includes a single corner with a large radius to require the user to properly orient cassette 24 in mounting location 145 or prevent door 141 from closing. However, it should be understood that other shape or orientation features for cassette 24 and / or mounting location 145 are possible.

[0156] According to an aspect of the invention, when cassette 24 is placed in mounting position 145, patient line 34, drain line 28, and heater bag line 26 are routed to the left through channel 40 in door 141, as shown in FIG. 31 . Channel 40, which may include guides 41 or other features, can hold patient line 34, drain line 28, and heater bag line 26, allowing occluder 147 to selectively open and close the lines for flow. When door 141 closes, occluder 147 can press one or more of patient line 34, drain line 28, and heater bag line 26 against occluder stop 29. Generally, when cycler 14 is operational (and operating properly), occluder 147 can allow flow through lines 34, 28, and 26, but can occlude the lines when cycler 14 is powered down (and / or not operating properly). Occlusion of the lines can be achieved by compressing the lines or pinching the lines to close the flow path in the lines. Preferably, the occluder 147 is capable of selectively occluding at least the patient line 34 and the drain line 28.

[0157] When cassette 24 is installed and door 141 is closed, the pump chamber side of cassette 24 and membrane 15 can be urged into contact with control surface 148 by, for example, an air bladder, spring, or other suitable configuration of door 141 behind mounting location 145 that compresses cassette 24 between mounting location 145 and control surface 148. Receiving cassette 24 in this manner can urge membranes 15 and 16 into contact with walls and other features of base member 18, thereby isolating channels and other flow paths of cassette 24 as desired. Control surface 148 can include a flexible gasket or membrane, for example, a sheet of silicone rubber or other material associated with membrane 15, allowing portions of membrane 15 to be selectively moved to effect pumping of pump chamber 181 and opening and closing valve ports of cassette 24. Control surface 148 can be associated with various portions of membrane 15, e.g., can be positioned in intimate contact with one another, such that portions of membrane 15 move in response to movement of corresponding portions of control surface 148. For example, membrane 15 and control surface 148 can be positioned proximate one another, and a suitable vacuum (or lower pressure relative to ambient) can be introduced and maintained between membrane 15 and control surface 148 through suitably positioned vacuum ports in control surface 148, such that membrane 15 and control surface 148 are essentially affixed to one another in areas of membrane 15 requiring movement to open or close a valve port and / or provide a pumping action, at least. In another embodiment, membrane 15 and control surface 148 can be glued or otherwise suitably associated with one another.

[0158] In some embodiments, the control surface 148 or surface of the gasket facing the corresponding cassette membrane overlying the pump chambers and / or valves is textured or roughened. The texturing creates a plurality of small passages horizontally or tangentially along the surface of the gasket as the gasket is pulled against the corresponding cassette membrane surface. This can facilitate evacuation between the gasket surface and the cassette membrane surface at the textured locations. It can also improve the accuracy of determining the pump chamber volume using a pressure-volume relationship (e.g., in the FMS procedure described elsewhere) by minimizing trapped air pockets between the gasket and the membrane. It can also facilitate the detection of any liquid that may be leaking into the space between the gasket and the cassette membrane. In embodiments, this can be achieved by masking portions of the gasket mold that will not form the portions of the gasket corresponding to the pump and valve membrane locations. The unmasked portions of the gasket mold can then be subjected to a chemical engraving process, such as the Mold-Tech® texturing and chemical engraving process. Texturing can also be achieved by any of a number of other processes, such as, for example, sandblasting, laser etching, or by using a mold manufacturing process that uses electrical discharge machining.

[0159] FIG. 32 shows a plan view of the control gasket 148 of the cycler 14, which interacts with the pump chamber side of the cassette 24 (e.g., as shown in FIG. 6) to cause fluid pumping and flow control within the cassette 24. The control gasket 148, which may comprise a sheet of silicone rubber, may be generally flat when at rest. A valve control region 1481 may (or may not) be defined in the control gasket 148, for example, by scoring, grooves, ribs, or other features in or on the surface of the sheet, and may be arranged to be movable or elastically deformable / stretchable generally transverse to the plane of the sheet. By moving inward / outward, the valve control region 1481 can move an associated portion of the membrane 15 on the cassette 24 to open or close the respective valve ports 184, 186, 190, and 192 of the cassette 24, thereby opening or closing the control ports of the cassette 24. The two larger regions, pump control region 1482, may likewise be movable to move an associated shaped portion 151 of membrane 15 that cooperates with pump chamber 181. Like shaped portion 151 of membrane 15, pump control region 1482 may be shaped to correspond to the shape of pump chamber 181 as control region 1482 extends into pump chamber 181. In this manner, the portion of control sheet or gasket 148 at pump control region 1482 does not necessarily have to stretch or elastically deform during pumping operations.

[0160] Typically, control gasket 148 is constructed from a single piece of material so that it can be easily formed from a mold. The flat portion of gasket 148 serves to compress and seal cassette membrane 15 against the boundary or peripheral wall of the cassette, sealing the fluid flow paths within cassette 24 when cassette 24 is pressed against control surface / gasket 148 and its supporting mating block. Similarly, when cassette 24 is pressed against control surface / gasket 148, fluid control ports 173A, 173C can seal against each other, so that control chambers 171A and 2746 can be individually and independently pressurized with positive or negative air pressure.

[0161] Alternatively, the moving portions of the control gasket 148, such as the pump control region 1482 and the valve control region 1481, may comprise a material having a different thickness, elasticity, and / or durometer than the flat portions of the gasket 148. The different materials may be fused together in a molding or overmolding operation, solvent bonded together, or attached using an adhesive. The pump control region 1482 and the valve control region 1482 of the gasket 148 are preferably constructed of an elastomeric material of a thickness and elasticity that allows them to move appropriately in response to positive or negative actuation pressures to move the associated pump and valve portions of the cassette membrane 15 a predetermined amount.

[0162] Each of regions 1481 and 1482 can have an associated vacuum or evacuation port 1483 that can be used, for example, to remove all or substantially all of any air or other fluid that may be present between the membrane 15 of the cassette 24 and the control surface 148 of the cycler 14 after the cassette 24 is loaded into the cycler 14 and the door 141 is closed. This can help ensure intimate contact of the membrane 15 with the control regions 1481 and 1482 and help control the delivery of a desired volume through pumping and / or the open / closed state of various valve ports. The vacuum port 1482 is formed in a location that does not cause the control surface 148 to come into contact with the wall or other relatively rigid feature of the cassette 24. For example, according to one aspect of the present invention, one or both of the pump chambers of the cassette can include a vacuum vent gap region formed adjacent to the pump chamber. In this exemplary embodiment as shown in FIGS. 3 and 6 , the base member 18 can include a vacuum vent port gap or expansion mechanism 182 (e.g., a recessed area fluidly connected to the pump chamber) adjacent to and outside of the oval-shaped recess forming the pump chamber 181, thereby allowing the vacuum vent port 1483 for the pump control region 1482 to unhinderedly remove any air or fluid from between the membrane 15 and the control surface 148 (e.g., by rupturing the membrane 15). The expansion mechanism can also be located within the outer periphery of the pump chamber 181. However, locating the vent port mechanism 182 outside the outer periphery of the pump chamber 181 can reserve more of the pump chamber volume for pumping fluid, e.g., the maximum footprint of the pump chamber 181 can be used to pump dialysate. Preferably, the expansion mechanism 182 is positioned vertically downward relative to the pump chamber 181, so that any fluid leaking between the membrane 15 and the control surface 148 is drawn through the vacuum port 1483 as quickly as possible. Similarly, the vacuum port 1483 associated with the valve 1481 is preferably positioned vertically below the valve 1481 .

[0163] 33A-C show that the control gasket 148 may optionally be constructed or molded to have rounded transitions between the base element 1480 of the control gasket 148 and the working portions of its valve and pump control regions 1481, 1482. These junctions or channels 1491 and 1492 may be molded with a small radius to transition from the base element 1480 to the valve control region 1481 and pump control region 1482, respectively. A rounded or smooth transition may help prevent premature fatigue and failure of the materials comprising the control gasket 148, improving its lifespan. In an optional embodiment, the radial channel 1484, leading from the vacuum port 1483 to the pump control region 1482 and valve control region 1481, may need to be somewhat longer to accommodate the transition feature. Junctions or channels 1491 and 1492 function as vacuum channels, transferring and distributing vacuum applied through the pressure delivery block to the potential space between pump control region 1482 and valve control region 1481 and the corresponding pump and valve portions of cassette membrane 15. If desired, these vacuum channels can also be used to transfer positive pressure to the potential space between gasket control region 1482 and the corresponding cassette membrane region to help isolate the cassette from the pressure delivery block. Exemplary vacuum channels 1491 and 1492 run along the periphery or perimeter of pump control region 1482 or valve control region 1481 of gasket 148, helping to allow for a more uniform application of vacuum.

[0164] Although not required, these vacuum channels 1491 and 1492 can optionally extend circumferentially around the pump and valve control regions of gasket 148, as shown, for example, in FIGS. 33A-C . For either pump control region 1482 or valve control region 1481 of gasket 148, the channel 1484 corresponding to a particular control region can be radially oriented to connect the nearby gasket vacuum port 1483 to the channel 1491 or 1492 extending along the periphery of its associated gasket control region. While vacuum channels 1491, 1492 need not completely surround the associated pump or valve control region to ensure uniform application of vacuum across the surface of the control region, the circumferential arrangement also serves the purpose of providing a flexible mechanical transition between the base element 1480 of gasket 148 and the body of gasket control region 1481 or 1482.

[0165] Control areas 1481 and 1482 can be moved by controlling air pressure and / or volume on the side of control surface 148 opposite cassette 24, e.g., the back surface of a rubber sheet forming control surface 148. For example, as shown in FIGS. 34-35 , a mating or pressure delivery block 170 can be positioned against the back surface of control surface 148, the mating or pressure delivery block 170 including control chambers or recesses 171A associated with each control area 1481, 1482 and control chambers or recesses 171B associated with each control area 1482 and isolated from each other (or at least controllable independently of each other, if desired). The surface of mating or pressure delivery block 170 forms a mating interface with cassette 24 when cassette 24 is pressed into operative association with control surface 148 against the back surface of mating block 170. Thus, the control chamber or recess in mating block 170 is coupled to a complementary valve or pointing chamber in cassette 24, sandwiching control areas 1481 and 1482 of control surface 148 adjacent mating block 170 and associated areas (such as molded portion 151) of membrane 15 adjacent cassette 24. Air or other control fluid can move in and out of control chambers or recesses 171A, 171B of mating block 170 relative to areas 1481, 1482, thereby moving control areas 1481 and 1482 as required to open or close valve ports in cassette 24 and / or provide pumping action in pump chamber 181. In the embodiment shown in FIGS. 34-35 , control chamber 171A may be arranged as a cylindrical area or recess lining each of valve control areas 1481 of gasket 148. In one configuration of valve control region 1481 of gasket 148 (see, e.g., FIGS. 33A-C), the surface of valve control region 1481 is slightly higher than the total surface of gasket 148, biasing the resiliently deformable control region toward a corresponding valve seat on cassette 24. Thus, positive air pressure applied to valve control region 1481 biases membrane 15 of cassette 24 toward sealing against the valve seat.On the other hand, at least a portion of the negative pressure applied to the valve control region 1481 to lift the adjacent cassette membrane 15 from its valve seat may be expended to overcome the biased valve control region 1481 of the control gasket 148. It is also apparent that when the gasket 148 is positioned against the underlying mating block 170, the space 1478 below the dome of the control region 1481 combines with the control chamber 171A to become a total control volume that can be pressurized positively or negatively to move the control region 1481 toward or away from the valve seat of the cassette 24. The amount of total control volume that needs to be pressurized varies based on the shape and configuration of the valve control region 1481 of the gasket (e.g., convex versus concave toward the cassette 24).

[0166] The control chambers or recesses 171B may include ellipsoidal, ovoid, or hemispherical cavities or recesses that contact the back surface of the pump control region 1482. For each control chamber 171A, a fluid control port 173A may be provided, thereby enabling the cycler 14 to control the fluid volume and / or fluid pressure in each of the valve control chambers 1481. For each control chamber 171B, a fluid control port 173C may be provided, thereby enabling the cycler 14 to control the fluid volume and / or fluid pressure in each of the volume control chambers 1482. For example, the mating block 170 may be mated with a manifold 172 that includes various ports, channels, openings, cavities, and / or other features that communicate with the control chambers 171 to allow a suitable air pressure / vacuum to be applied to the control chambers 171. Although not shown, air pressure / vacuum control may be achieved in any suitable manner, such as by using controllable valves, pumps, pressure sensors, accumulators, etc. Of course, it should be understood that the control areas 1481, 1482 can be moved in other ways, such as by a gravity-based system, a hydraulic system and / or a mechanical system (such as by a linear motor), or by a combination of systems including pneumatic, hydraulic, gravity-based and mechanical systems.

[0167] FIG. 36 shows an exploded view of an integrated pressure distribution module or assembly 2700 suitable for use in a fluid flow control device that operates a pump cassette and as the pressure distribution manifold 172 and mating block 170 of the cycler 14. FIG. 94 shows a diagram of the integrated module 2700, which includes a pneumatic manifold or block, ports for supply pressure, pneumatic control valves, pressure sensors, a pressure delivery or mating block, and a control surface or actuator including an area with a flexible membrane that actuates the pumps and valves on the pump cassette. The integrated module 2700 can also include a reference chamber within the pneumatic manifold for the FMS volumetric measurement process that determines the volume of fluid present in the pump chamber of the pump cassette. The integrated module can also include a vacuum port and a set of passages or channels from the interface between the actuator and the flexible pump and valve membranes of the pump cassette to the fluid trap and liquid detection system. In some embodiments, the pneumatic manifold can be formed as a single block. In other embodiments, a pneumatic manifold can be formed from two or more manifold blocks mated together with a gasket disposed between the manifold blocks. The integrated module 2700 occupies a relatively small space in the fluid flow control device and eliminates the use of tubing or flexible conduits connecting manifold ports to corresponding ports on a pressure delivery module or block mated to the pump cassette. Among other possible advantages, the integrated module 2700 reduces the size and assembly cost of the pneumatic actuation assembly of a peritoneal dialysis cycler, resulting in a more compact and inexpensive cycler. Furthermore, the short distance between the pressure or vacuum distribution ports of the pressure distribution manifold block and the corresponding pressure or vacuum delivery ports of the mating pressure delivery block, combined with the stiffness of the conduits connecting the ports, can improve the responsiveness of the attached pump cassette and the accuracy of the cassette pump volume measurement process.When used in a peritoneal dialysis cycler 14, in embodiments, the integrated module, which includes a metal pressure distribution manifold that fits directly into the metal pressure delivery block, can also reduce any temperature difference between the control valve 171B and the reference chamber 174 of the cycler 14, thereby improving the accuracy of the pump volume measurement process.

[0168] FIG. 36 provides an exploded view of the integrated module 2700. The actuator face or control gasket 148 attached to the mating block or pressure delivery block includes a flexible region arranged to move back and forth to push or pull on the membrane 15 of the pump cassette 24, thereby pumping fluid and / or opening and closing a valve. With respect to the cycler 14, the control gasket 148 is actuated by positive and negative air pressure supplied to the control volumes 171A, 171B behind the control regions 1481, 1482. The control gasket 148 is attached to the pressure delivery or mating block 170 by a lip 2742 that fits snugly over a raised surface 2744 on the front of the mating block 170. The mating block 170 can include one or more surface indentations 2746 that align with and support the oval curved shape of one or more corresponding pump control faces 1482 to form a pump control chamber. Similar features, with or without surface depressions, can be included in forming the valve control region 171A to align with corresponding control surfaces 1481 for controlling one or more valves of the pump cassette. The mating block 170 can further include grooves 2748 in the surface of the depressions 2746 of the mating block 170 rearward of the pump control surface 1482 to facilitate flow of control fluid or gas from the ports 173C to the entire rear pump control surface 1482. Alternatively, rather than having grooves 2748, the depressions 2746 can be formed with a roughened or tangentially porous surface.

[0169] In one embodiment, the inner walls of the control chamber 171B may include raised elements (somewhat similar to the spacer elements 50 of the pump chamber 181), as shown, for example, in FIG. 34 associated with the pump control region 1482. These raised elements may take the form of plateau features, ribs, or other protrusions that keep the control ports set back from the fully retracted control region 1482. This arrangement may allow for a more even distribution of pressure or vacuum within the control chamber 171B and prevent premature blocking of the control ports by the control gasket 148. The preformed control gasket 148 (at least in the pump control region) should not experience significant elongation forces when fully extended against either the inner walls of the pump chamber of the cassette 24 during the delivery stroke or the inside of the control chamber 171 during the fill stroke. Thus, the control region 1482 may extend asymmetrically into the control chamber 171B, causing the control region 1482 to prematurely close one or more ports in the control chamber before the chamber is fully evacuated. Having features on the interior surface of the control chamber 171B that prevent contact between the control region 1482 and the control ports may help ensure that the control region 1482 can make uniform contact with the control chamber interior wall during the fill stroke.

[0170] Mating block 170 connects pressure distribution manifold 172 to control surface 148 and delivers pressure or vacuum to the various control regions of control surface 148. Mating block 170 can also be referred to as a pressure delivery block, in that it provides pneumatic conduits that supply pressure and vacuum to valve control region 1481 and pump control region 1482, and vacuum from vacuum port 1483 and the connection from pump control volume 171B to the pressure sensor. Port 173A connects control volume 171A to pressure distribution manifold 172. Port 173C connects pump control volume 171B to pressure distribution manifold 172. Vacuum port 1483 is connected to pressure distribution manifold 172 through port 173B. In one embodiment, port 173B extends above the surface of pressure distribution block 170 past control surface 148 to provide vacuum at port 1483 without pulling control surface 148 onto port 173B and obstructing flow.

[0171] The pressure delivery block 170 is attached to the surface of the pressure distribution manifold 172. Ports 173A, 173B, and 173C align with the pneumatic circuit of the pressure distribution manifold 172, which connects to valve port 2714. In one example, the pressure delivery block 170 mates with the pressure distribution manifold 172, with a front flat gasket 2703 clamped between them. The block 170 and manifold 172 are held together mechanically, in embodiments, by using bolts 2736 or other types of fasteners. In another example, a high-compliance element is placed or molded into either the pressure delivery block 170 or the pressure distribution manifold 172, rather than the flat gasket 2703. Alternatively, the pressure delivery block 170 can be bonded to the pressure distribution manifold 172 with adhesive, double-sided tape, friction welding, laser welding, or other bonding methods. The block and manifold 172 can be made of metal or plastic, and the bonding method varies depending on the material.

[0172] 38, the pressure distribution manifold 172 includes ports for pneumatic valves 2710, a reference chamber 174, a fluid trap 1722, and an integrated module 2700 connection that provides pneumatic connections between the pneumatic circuit, or pressure reservoir, and the valves, and includes ports 2714 to accept multiple cartridge valves 2710. Cartridge valves 2710 include, but are not limited to, binary valve 2660, which controls flow to valve control volume 171A; binary valves X1A, X1B, X2, and X3, which control flow to pump control volume 171B; and binary valves 2661-2667, which control flow to bladders 2630, 2640, and 2650 and pressure reservoirs 2610 and 2620. Cartridge valves 2710 are press-fit into valve ports 2714 and electrically connected to the hardware interface 310 via circuit board 2712.

[0173] Pneumatic circuits in the pressure distribution manifold 172 can be formed by a combination of grooves or slots 1721 on the front and back surfaces and approximately vertical holes connecting the grooves 1721 on one surface to the valve ports 2714, fluid traps 1722, and to the grooves and ports on the opposing surface. Some grooves 1721 can connect directly to the reference chamber 174. A single vertical hole can connect a groove 1721 to multiple closely spaced and staggered valve ports 174. When the grooves 1721 are isolated from each other, in one example by a front flat gasket 2703 as shown in FIG. 36, a sealed pneumatic conduit is formed.

[0174] The presence of liquid in the fluid trap 1722 can be detected by a pair of conductive probes 2732. The conductive probes 2732 slide through the back gasket 2704, back plate 2730 and holes 2750 before entering the fluid trap 1722 of the pressure distribution manifold 172.

[0175] The back plate 2730 seals the reference volume 174, the groove 1721 on the back of the pressure distribution manifold 172, and provides ports for the pressure sensor 2740 as well as ports for the pressure and vacuum lines 2734, and a vent to atmosphere 2732. In one example, the pressure sensor can be an IC chip soldered to a single substrate 2740 and pressed together against the back gasket 2704 of the back plate 2730. In one example, bolts 2736 fasten the back plate 2730, pressure distribution manifold 172, and pressure delivery block 170 together, with gaskets 2703, 2702 between them. In another example, the back plate 2730 can be bonded to the pressure delivery manifold 172 as described above. FIG. 95 shows the assembled integrated module 2700.

[0176] FIG. 38 presents a schematic diagram of the pneumatic circuit within the integrated manifold 2700 and the pneumatic elements outside the manifold. Pump 2600 generates vacuum and pressure. Pump 2600 is connected to vent 2680 and negative pressure or vacuum reservoir 2610 and positive pressure reservoir 2620 via three-way valves 2664 and 2665. The pressure in positive pressure reservoir 2620 and negative pressure reservoir 2610 is measured by pressure sensors 2678 and 2676, respectively. Hardware interface 310 controls the speed of pump 2600 and the position of three-way valves 2664, 2665, and 2666 to control the pressure in each reservoir. Auto-connect stripper element bladder 2630 is connected to either positive pressure line 2622 or negative pressure or vacuum line 2612 via three-way valve 2661. Automation computer 300 commands the position of valve 2661 to control the position of stripper element 1461. Occluder bladder 2640 and piston bladder 2650 are connected to either pressure line 2622 or vent 2680 via three-way valves 2662 and 2663. Automation computer 300 commands valve 2663 to connect piston bladder 2650 to pressure line 2622 after door 141 is closed to securely engage cassette 24 against control surface 148. Occluder bladder 2640 is connected to pressure line 2622 via valve 2662 and restriction 2682. Occluder bladder 2640 is connected to vent 2680 via valve 2662. Orifice 2682 advantageously delays filling of occluder bladder 2640, which retracts occluder 147, to maintain pressure in pressure line 2622. High pressure in pressure line 2622 keeps the various valve control surfaces 171A and piston bladder 2650 actuated against cassette 24, preventing flow to or from the patient when occluder 147 opens. Conversely, the connection from the occluder bladder 2640 to the vent 2680 is not restricted, so the occluder 147 can close quickly.

[0177] Valve control surface 1481 is controlled by the pressure in valve control volume 171A, which in turn is controlled by the position of three-way valve 2660. Valves 2660 can be individually controlled via commands from automation computer 300 sent to hardware interface 310. The valve controlling the pumping pressure in pump control volume 171B is controlled by two-way valves X1A and X1B. Valves X1A and X1B can, in one example, be controlled by hardware interface 310 to reach a pressure commanded by automation computer 300. The pressure in each pump control chamber 171B is measured by sensor 2672. The pressure in the reference chamber is measured by sensor 2670. Two-way valves X2 and X3 connect reference chamber 174 to pump control chamber 171B and vent 2680, respectively.

[0178] The fluid trap 1722 is connected to the vacuum line 2612 during operation, as described elsewhere herein. The fluid trap 1722 is connected by several lines to ports on the pressure delivery block 170. The pressure within the fluid trap 1722 is monitored by a pressure sensor 2674 attached to the back plate 2730.

[0179] At the end of treatment, the vacuum port 1483 can be employed to separate the membrane 15 from the control surface 148 before or while the door is open. Vacuum provided to the vacuum port 1483 by a negative pressure source seals the membrane 15 against the control surface 148 during treatment. In some cases, even when the vacuum is applied intermittently, a substantial amount of force may be required to prevent the door 141 from freely rotating to the open position and separate the control surface from the cassette membrane 15. Therefore, in embodiments, the pressure distribution module 2700 is configured to provide a valved channel between the positive pressure source and the vacuum port 1483. Providing positive pressure at the vacuum port 1483 can help separate the membrane 15 from the control surface 148, allowing the cassette 24 to more easily separate from the control surface 148 and free the door 141 to open. A pneumatic valve in the cycler can be controlled by the automation computer 300 to provide positive pressure to the vacuum port 1483. Manifold 172 may include a separate valved channel dedicated to this purpose, or alternatively may employ existing channel configurations and valves that are operated in a particular sequence.

[0180] In one example, positive pressure can be supplied to the vacuum port 1483 by temporarily connecting the vacuum port 1483 to a positive pressure reservoir 2620. The vacuum port 1483 is typically connected to the vacuum reservoir 2610 during treatment through a common fluid connection chamber or fluid trap 1722 in the manifold 172. In one example, the controller or automation computer can simultaneously open valve X1B between the positive pressure reservoir and volume control chamber 171B and valve X1A between the negative pressure reservoir and the same volume control chamber 171B, thereby pressurizing the air in the fluid trap 1722 and the vacuum port 1483. The pressurized air flows through the vacuum port 1483 between the membrane 15 and the control surface 148, breaking any vacuum connection between the membrane and the control surface. However, in the illustrated manifold, the stripper element 1491 of the cap stripper 149 can expand while positive pressure is applied to the common fluid collection chamber 1722 because the stripper bladder 2630 is connected to the vacuum supply line 2612. In this example, in a subsequent step, the fluid trap 1722 can be valved off from the newly pressurized vacuum line, and the two valves X1A and X1B connecting the positive pressure reservoir and vacuum reservoir to the volume control chamber 171B can be closed. The vacuum pump 2600 can then be operated to reduce the pressure in the vacuum reservoir 2610 and the vacuum supply line 2612, thereby retracting the stripper element 1491. The cassette 24 can then be removed from the control surface 148, and the stripper element 1491 can be retracted before the door 141 can be opened.

[0181] According to embodiments of the present disclosure, the vacuum port 1483 can be used to detect leaks in the membrane 15, and a liquid sensor in a conduit or chamber connected to the vacuum port 1483 can detect liquid if the membrane 15 is pierced or otherwise introduced between the membrane 15 and the control gasket 148. For example, the vacuum port 1483 can be aligned with and sealingly associated with a complementary vacuum port 173B in the mating block 170, thereby sealingly associating the complementary vacuum port 173B with a fluid passageway 1721 that leads to a common fluid collection chamber 1722 in the manifold 172. The fluid collection chamber 1722 can include an inlet through which a vacuum can be applied and distributed to all of the vacuum ports 1483 on the control surface 148. Applying a vacuum to the fluid collection chamber 1722 can draw fluid from each of the vacuum ports 173B and 1483, thus removing fluid from any space between the membrane 15 and the control surface 148 in the various control regions. However, if liquid is present in one or more of the regions, the associated vacuum port 1483 can draw liquid into the vacuum port 173B and into the line 1721 leading to the fluid collection chamber 1722. Any such liquid collects in the fluid collection chamber 1722 and can be detected by one or more suitable sensors, for example, a pair of conductivity sensors that detect a change in conductivity in the chamber 1722, indicating the presence of liquid. In this embodiment, the sensors can be located on the bottom side of the fluid collection chamber 1722, and the vacuum source connects to the chamber 1722 at its top. Thus, if liquid is drawn into the fluid collection chamber 1722, the liquid can be detected before the liquid level reaches the vacuum source. Optionally, a hydrophobic filter, valve, or other component can be located at the vacuum source connection to the chamber 1722 to help further resist liquid from entering the vacuum source. In this way, the controller 16 can detect and act upon a liquid leak (e.g., issue an alarm, close the liquid inlet valve, or stop pumping operations) before the vacuum source valve is positioned such that it is at risk of being contaminated by the liquid.

[0182] The example schematic shown in Figure 38 shows a calibration port 2684. The calibration port 2684 can be used to calibrate the various pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 in the pneumatic system. For example, a pressure reference can be connected to the pneumatic circuit of the cycler through the calibration port 2684. With the pressure reference connected, the valves in the pneumatic system can be actuated to connect all of the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 to the same fluid volume. The pressure reference can then be used to establish a known pressure in the pneumatic system. Pressure measurements from each of the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 can be compared to a known pressure reference and the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 can be calibrated accordingly. In some embodiments, selected ones of the pressure sensors 2672, 2674, 2676, 2677, 2678 can be connected to and referenced to the pressure reference for calibration, either as a group or individually.

[0183] Any fluid treatment device (i.e., base unit) configured to operate diaphragm-based pumps and valves in a removable cassette can utilize its pneumatic (or hydraulic) cassette interface to receive a calibration reference pressure via a dedicated calibration cassette (or "cassette fixture"). The calibration cassette can have the same overall dimensions as a standard fluid pump cassette, thereby providing a sealing interface with the cassette interface or control surface of the base unit. One or more of the pump or valve regions can be enabled to communicate with corresponding regions of the mating interface, thereby introducing a reference pneumatic or hydraulic pressure through the calibration cassette and into the pneumatic or hydraulic flow path of the base unit (e.g., via a pneumatic or hydraulic manifold).

[0184] For example, in a pneumatically actuated peritoneal dialysis cycler, the pneumatic circuit of the cycler can be directly accessed through the cassette interface of the cycler. This can be accomplished, for example, using a modified cassette or cassette fixture that allows control surface 148 to create a seal against the cassette fixture. Additionally, the cassette fixture can be configured to include at least one access port that is in fluid communication with vacuum port 173B of the cassette interface. In the absence of a vacuum port (e.g., in embodiments having slits or pores in the control surface), the access port can instead be positioned to communicate with a vacuum vent mechanism on the cassette interface or control surface.

[0185] The cassette fixture (or calibration cassette) can be constructed to have a direct flow path from the external cassette port to an access port facing the device interface, which can be used to connect to a pressure reference. As described above, all or some of the pressure sensors 2670, 2672, 2674, 2676, 2677, and 2678 can be placed in fluid communication with a common volume by appropriately activating pneumatic control valves in the pressure distribution manifold. A known pressure can be established within that volume using the pressure reference. Pressure measurements from each of the pressure sensors 2670, 2672, 2674, 2676, 2677, and 2678 can be compared to the known pressure of the pressure reference, and the pressure sensors 2670, 2672, 2674, 2676, 2677, and 2678 can be calibrated accordingly.

[0186] In some embodiments of the pressure distribution manifold, it may not be possible for all of the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 to be connected to a common volume at one time. In that case, the flow paths to the individual pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 may need to be opened sequentially to ensure calibration of all sensors. Furthermore, it should be noted that once calibrated, one or more of the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 can be used to calibrate the pressure sensors 2670, 2672, 2674, 2676, 2677, 2678 in the pressure distribution manifold of the base unit or cycler. One or more previously calibrated pressure sensors can be placed in a common volume with uncalibrated pressure sensors (e.g., via suitable valve actuation). The pressure in the common volume may be known via a calibrated pressure sensor. The measurements of the uncalibrated pressure sensor can be compared to the known pressure in the common volume and then calibrated accordingly.

[0187] FIG. 39 shows a schematic diagram of an embodiment of a cassette fixture 4570. As shown, the cassette fixture 4570 has the same exterior shape as the standard pump cassette 24 described above. The cassette fixture 4570 includes access ports 4572 associated with predetermined valve or pump regions of the standard cassette to align with corresponding regions of the cassette interface (control surface 148) of the base unit. The cassette fixture 4570 can have an otherwise flat, smooth interface surface so that the control surface can seal against the base unit or cycler when mated thereto. Preferably, the cassette fixture 4570 is formed from metal or other hard, rigid material. Resistance to bending or deformation under pressure can help improve reliability and consistency across multiple calibrations of multiple cyclers. As shown, the cassette fixture 4570 includes access ports 4572 recessed into the face of the cassette fixture 4570. The access port 4572 communicates with a flow path 4573 that extends to a tube 4574 that leads away from the cassette fixture 4570. In an example embodiment, a cassette port or fitting can be included on the side of the cassette to connect via a tube to a reference pressure source 4576.

[0188] 40 and 41 show another representation of a cassette fixture 4570 adapted from a modified cassette, such as cassette 24 shown in FIG. 3. In such an example, the cassette fixture 4570 can be created by removing or omitting a sheet or membrane from the control side of the cassette that, when installed in the cycler, faces the cycler's control surface or cassette interface 148 (see, e.g., FIGS. 33A-C). With reference to FIG. 3, for example, cassette 24 may not include membrane 15. Thus, the cycler's pneumatic circuitry can be directly accessed through cassette 24. Alternatively, the membrane or sheet can be interrupted (e.g., removed, perforated, slit, etc.) in only a portion of the cassette to create the cassette fixture 4570. For example, the membrane can be modified in this manner in the area where access port 4572 of cassette fixture 4570 is located.

[0189] Additionally, tubing 4574 can be attached to one or more of the external connection points of the standard cassette to create the necessary fluid communication paths in the cassette fixture 4570. The external connection points can include any tubing attachment points on the standard cassette or can include more robust fittings for repeated use in calibration procedures. With reference to FIG. 3 , the external connection points can include cassette spike 160 and / or ports 150, 152, and 154. The cassette can then be modified so that all of the other external connection points can be closed, plugged, or otherwise sealed.

[0190] As described above, tubing 4574 leads from a fluid flow path 4573 that is fluidly connected to an access port 4572 in the cassette fixture 4570 so as to provide a connection to a pressure reference 4576. The access port 4572 can be an existing opening or valve port in the cassette body. Furthermore, the fluid path 4573 can be any existing passage or combination of passages in the cassette body that allows fluid communication from the access port 4572 to the tubing 4574 or associated fittings on the cassette side. For example, the flow path 4573 can include one or more valve ports, valve wells, pump chambers, and / or channels in the cassette body, or any combination thereof.

[0191] As alluded to above, cycler 14 may include a control system 16 with a data processor in electronic communication with the various valves, pressure sensors, motors, etc. of the system, and is preferably configured to control such components according to a desired sequence or protocol of operation. Control system 16 may include appropriate circuitry, programming, computer memory, electrical connections, and / or other components to perform designated tasks. The system may include pumps, tanks, manifolds, valves, or other components to generate the desired air or other fluid pressure (positive pressure above atmospheric pressure or some other reference, or negative pressure or vacuum below atmospheric pressure or some other reference) to control the operation of the area of ​​control surface 148 and other pneumatically actuated components. Further details regarding control system 16 (or at least portions thereof) are provided below.

[0192] In one exemplary embodiment, the pressure in the pump control chamber 171B can be controlled by a binary valve, which, for example, opens to expose the control chamber 171 to a suitable pressure / vacuum and closes to block the pressure / vacuum source. The binary valve can be controlled using a sawtooth-shaped control signal that can be adjusted to control the pressure in the pump control chamber 171B. For example, during a pump delivery stroke (i.e., when positive pressure is introduced into the pump control chamber 171B to move the membrane 15 / control surface 148 and force liquid out of the pump chamber 181), the sawtooth signal can drive the binary valve to open and close relatively rapidly to establish a suitable pressure in the control chamber 171B (e.g., a pressure of approximately 70 mmHg to 90 mmHg). If the pressure in the control chamber 171B rises above approximately 90 mmHg, the sawtooth signal can be adjusted to close the binary valve for a longer period of time. If the pressure in control chamber 171B drops below about 70 mmHg, the sawtooth control signal can be reapplied to the binary valve to increase the pressure in control chamber 171. Thus, during normal pump operation, the binary valve can be opened and closed multiple times and closed for one or more extended periods, thereby maintaining the pressure at a desired level or range (e.g., about 70 mmHg to 90 mmHg) as the liquid is forced out of pump chamber 181.

[0193] In some embodiments, and according to aspects of the present disclosure, it may be useful to detect the "end of stroke" of the membrane 15 / pump control region 1482, for example, when the membrane 15 contacts the spacer 50 of the pump chamber 181 or the pump control region 1482 contacts the wall of the pump control chamber 171B. For example, during a pumping operation, detecting the "end of stroke" can indicate that the movement of the membrane 15 / pump control region 1482 should be reversed to initiate a new pump cycle (to fill the pump chamber 181 or to push fluid out of the pump chamber 181). In one exemplary embodiment in which the pressure in the control chamber 171B for the pump is controlled by a binary valve driven by a sawtooth control signal, the pressure in the pump chamber 181 fluctuates at a relatively high frequency, for example, at or near the frequency at which the binary valve is opened and closed. A pressure sensor in control chamber 171B can detect this fluctuation, which generally has a relatively high amplitude when membrane 15 / pump control region 1482 is not in contact with the inner wall of pump chamber 181 or the wall of pump control chamber 171B. However, once membrane 15 / pump control region 1482 contacts the inner wall of pump chamber 181 or the wall of pump control chamber 171B (i.e., "end of stroke"), the pressure fluctuation generally dampens or otherwise changes so as to be detectable by the pressure sensor in pump control chamber 171B. This change in pressure fluctuation can be used to identify end of stroke and the pump and other components of cassette 24 and / or cycler 14 can be controlled accordingly.

[0194] In one embodiment, the air pressure applied to the control chamber 171B is actively controlled by a processor that receives signals from a pressure transducer 2672 (FIG. 38) connected to the control chamber 171B and from fast-acting binary valves X1A, X1B between the pressure reservoirs 2620, 2610 and the control chamber 171B. The processor can control the pressure using a variety of control algorithms, including closed-loop proportional or proportional-integral feedback control, which varies the duty cycle of the valves to achieve the desired pressure within the control volume 171B. In one embodiment, the processor controls the pressure in the control chamber using an on-off controller, often referred to as a bang-bang controller. The on-off controller monitors the pressure in control volume 171B during the delivery stroke, opening binary valve X1B (connecting control volume 171B to positive pressure reservoir 2620) when the pressure is below a first lower limit and closing binary valve X1B when the pressure exceeds a second upper limit. During the fill stroke, the on-off controller opens binary valve X1A (connecting control volume 171B to negative pressure reservoir 2610) when the pressure is greater than a third limit and closes binary valve X1A when the pressure is less than a fourth limit, where the fourth limit is less than the third limit and both the third and fourth limits are less than the first limit. A plot of pressure over time, such as during the delivery stroke and subsequent FMS measurements, is shown in FIG. 114. The control chamber pressure 2300 oscillates between a first lower limit 2312 and a second upper limit 2310 as the membrane 15 moves across the control chamber 171B. When the membrane 15 stops moving, the pressure stops oscillating between the limits. The membrane 15 typically stops moving when it contacts the cassette's stadium stage 50 or when it contacts the control chamber surface 171B. The membrane 15 can also stop moving if the outlet fluid line is blocked.

[0195] The automation computer (AC) 300 detects the end of stroke by evaluating the pressure signal. There are many possible algorithms for detecting the end of the pressure oscillation, which indicates the end of stroke (EOS). The algorithms and methods for detecting EOS are incorporated herein by reference in the section entitled "Detailed Description of the system and method of measuring change fluid flow rate" in U.S. Pat. No. 6,520,747 and in the section describing filtering to detect the end of stroke in U.S. Pat. No. 8,292,594.

[0196] In one example of an algorithm for detecting EOS, the AC300 evaluates the time between pressure exceeding a first and second limit during a delivery stroke, or between a third and fourth limit during a fill stroke. An on-off controller opens and closes valves X1A and X1B in response to the pressure oscillating between the two limits as the control chamber volume changes during the fill or delivery stroke. When the membrane 15 stops moving at the end of the stroke, the pressure change significantly reduces so that the pressure no longer exceeds one or both limits. The AC300 can detect EOS by measuring the time between pressure exceeding alternate limits. If the time since the pressure exceeded the last limit exceeds a predetermined threshold, the AC300 can declare EOS. The algorithm can further include an initial phase in which the AC300 does not measure the time between limit exceedances.

[0197] In another example algorithm, the AC300 evaluates the derivative of the pressure signal with respect to time. If the derivative remains below a minimum threshold for a minimum time, the AC300 can declare EOS. In a further example, the minimum threshold is the average of the absolute value of the average pressure derivative during the stroke. The algorithm calculates the slope (derivative with respect to time) of a curve fit to a set of data points, where the data points are taken from a moving window. The absolute value of the average pressure derivative is then calculated by averaging the absolute value of each slope over the stroke. In another example of an EOS algorithm, the AC300 may not include pressure data until after an initial delay. The AC300 ignores early pressure data to avoid inaccurate EOS detection due to irregular pressure traces that sometimes occur during the early portion of the stroke. In another example, the AC300 declares EOS only if the second derivative of the pressure in the later portion of the stroke remains below a threshold for a minimum time and after the wait period has elapsed.

[0198] The criteria for declaring EOS can be optimized for various pumping conditions. Optimized EOS detection conditions include a second-order pressure derivative threshold, a minimum time remaining below the second-order derivative threshold, the duration of the initial delay, and the length of the wait period. These EOS detection criteria can be optimized differently, for example, for the fill stroke from bags 20, 22, the delivery stroke to the patient, the fill stroke from the patient, and the delivery stroke to bags 20, 22. Alternatively, each EOS detection criterion can be a function of the pumping pressure in control chamber 171B.

[0199] Pump delivery volume measurement In another aspect of the invention, cycler 14 can determine the volume of fluid delivered to various lines of system 10 without the use of flow meters, weigh scales, or other direct measures of fluid volume or weight. For example, in one embodiment, the volume of fluid moved by a pump, such as a pump in cassette 24, can be determined based on pressure measurements of the gas used to drive the pump. In one embodiment, the volume can be determined by isolating two chambers from each other, measuring the pressure in each of the isolated chambers, and fluidly connecting the two chambers to partially or substantially equalize the pressures in the two chambers and measuring the pressures. Using the measured pressure, the known volume of one of the chambers, and the assumption that equalization occurs adiabatically, the volume of the other chamber (e.g., the pump chamber) can be calculated. In one embodiment, the pressures measured after the chambers are fluidly connected may not be substantially equal to each other, i.e., the pressures in the chambers may not yet be completely equalized. However, as described below, these substantially unequal pressures can be used to determine the volume of the pump control chamber.

[0200] For example, FIG. 43 shows a schematic diagram of pump chamber 181 of cassette 24 and associated control components and inflow / outflow paths. In this illustrative example, a fluid supply, which may include heater bag 22, heater bag line 26, and a fluid path through cassette 24, is shown providing fluid input to upper opening 191 of the pump chamber. A fluid outlet, in this example, is shown receiving fluid from lower opening 187 of pump chamber 181 and may include, for example, the fluid path of cassette 24 and patient line 34. The fluid supply may include a valve, including, for example, valve port 192, which may be opened or closed to allow / prevent flow to / from pump chamber 181. Similarly, the fluid outlet may include a valve, including, for example, valve port 190, which may be opened or closed to allow / prevent flow to / from pump chamber 181. Of course, the fluid source can include any suitable configuration, such as one or more solution containers, a patient line, one or more flow paths within cassette 24, or other fluid sources, and the fluid outlet can similarly include any suitable configuration, such as a drain line, a heater bag and heater bag line, one or more flow paths within cassette 24, or other fluid outlets. Generally, pump chamber 181 (i.e., to the left of membrane 14 in FIG. 43 ) is filled with an incompressible fluid, such as water or dialysate, during operation. However, under some circumstances, such as during initial operation, priming, or other circumstances as described below, air or other gas may be present within pump chamber 181. Also, while aspects of the invention relating to pump volume and / or pressure sensing are described with respect to the pump configuration of cassette 24, it should be understood that aspects of the invention can be used with any suitable pump or fluid transfer system.

[0201] 43 also shows schematically a control chamber 171B to the right of the membrane 15 and control surface 1482 (which are adjacent to each other), which, as described above, may be formed as a void or other space in the mating block 170A associated with the pump control region 1482 of the control surface 1482 relative to the pump chamber 181. It is in the control chamber 171B that suitable air pressure is introduced to move the membrane 15 / control region 1482 and pump the liquid in the pump chamber 181. The control chamber 171B may communicate with a line L0, which branches to another line L1 and a first valve X1 in communication with a pressure source 84, for example an air pressure source or a vacuum source. The pressure source 84 can include a piston pump, where a piston moves within a chamber to control the pressure delivered to the control chamber 171, or it can include different types of pressure pumps and / or tanks to deliver a suitable gas pressure to move the membrane 15 / control region 1482 and perform the pumping action. Line L0 can also lead to a second valve X2, which communicates with another line L2 and a reference chamber 174 (e.g., a space suitably configured for measurements, as described below). The reference chamber 174 also communicates with a line L3 having a valve X3, which communicates with a vent or other reference pressure (e.g., an atmospheric pressure source or other reference pressure source). Each of the valves X1, X2, and X3 can be independently controlled. Pressure sensors can be positioned to measure pressures associated with the control and reference chambers, e.g., one sensor in the control chamber 171 and another in the reference chamber. These pressure sensors can be positioned and operated to detect pressure in any suitable manner. The pressure sensor may be in communication with the control system 16 for the cycler 14 or other suitable processor that determines the volume delivered by the pump or other mechanism.

[0202] As discussed above, the valves and other components of the pump mechanism shown in FIG. 43 can be controlled to measure the pressure in the pump chamber 181, the liquid source, and / or the liquid outlet, and / or to measure the volume of liquid delivered from the pump chamber 181 to the liquid source or liquid outlet. With respect to volume measurements, one technique used to determine the volume of fluid delivered from the pump chamber 181 is to compare the relative pressure in the control chamber 171B to the pressure in a reference chamber at two different pump states. By comparing the relative pressures, the change in volume of the control chamber 171B can be determined, which corresponds to the change in volume of the pump chamber 181 and reflects the volume delivered from / received by the pump chamber 181. For example, after the pressure in the control chamber 171B is reduced during a pump chamber fill cycle (e.g., by applying negative pressure from a pressure source through an open valve X1) to draw the membrane 15 and pump control region 1482 into contact with at least a portion of the control chamber wall (or to another suitable position of the membrane 15 / region 1482), valve X1 can be closed to isolate the control chamber from the pressure source, and valve X2 can be closed, thereby isolating the reference chamber from the control chamber 171B. Valve X3 can be opened to vent the reference chamber to atmospheric pressure and then closed to isolate the reference chamber. With valve X1 closed and the pressure in the control and reference chambers being measured, valve X2 can then be opened to initiate equalization of the pressures in the control and reference chambers. The initial pressures in the reference and control chambers, along with the known volume of the reference chamber and the pressure measured after equalization has begun (but not necessarily completed), can be used to determine the volume of the control chamber. At the end of the pump delivery cycle, the above process can be repeated when the sheet 15 / control region 1482 is forced into contact with the spacer element 50 of the pump chamber 181. By comparing the control chamber volume at the end of the fill cycle with the volume at the end of the delivery cycle, the volume of liquid delivered from the pump can be determined.

[0203] Conceptually, the pressure equalization process (e.g., when valve X2 is opened) can be viewed as occurring adiabatically, i.e., without heat transfer between the air in the control and reference chambers and the air in their surrounding environments. The conceptual idea is that when valve X2 is closed, a virtual piston is initially positioned at valve X2, and when valve X2 is opened, the virtual piston moves in line L0 or L2, equalizing the pressures in the control and reference chambers. Because (a) the pressure equalization process occurs relatively quickly, (b) the air in the control and reference chambers has approximately the same element concentrations, and (c) the temperatures are similar, the assumption that pressure equalization occurs adiabatically may introduce only small errors in the volume measurement. Also, in one embodiment, pressures obtained after equalization has begun can be measured before substantial equalization occurs, further shortening the time between the initial and final pressure measurements used to determine the pump chamber volume. Additionally, errors can be further reduced by using materials with low thermal conductivity for, for example, the membrane 15 / control surface 1482, cassette 24, control chamber 171, lines, reference chamber 174, etc., to reduce heat conduction.

[0204] Assuming an adiabatic system exists while valve X2 is closed until after valve X2 is opened and the pressures have equalized, the following equations apply: PV γ =Constant(1) where P is pressure, V is volume, and γ is equal to a constant (e.g., approximately 1.4 if the gas is diatomic such as air). Thus, the following equation can be written to relate the pressure and volume in the control and reference chambers before and after valve X2 opens and pressure equalization occurs:

[0205] PrVr γ +PdVd γ =Constant=PfVf γ (2) where Pr is the pressure in the reference chamber and lines L2 and L3 before opening valve X2, Vr is the volume of the reference chamber and lines L2 and L3 before opening valve X2, Pd is the pressure in the control chamber and lines L0 and L1 before opening valve X2, Vd is the volume of the control chamber and lines L0 and L1 before opening valve X2, Pf is the equalized pressure in the reference and control chambers after opening valve X2, and Vf is the volume of the entire system including the control chamber, reference chamber, and lines L0, L1, L2, and L3, i.e., Vf = Vd + Vr. Since Pr, Vr, Pd, Pf, and γ are known and Vf = Vr + Vd, this equation can be used to solve for Vd. (Although reference is made herein to the use of "measured pressure" in determining volume values ​​and the like, it should be understood that such measured pressure values ​​need not necessarily be in any particular format, such as in psi units.) Alternatively, a "measured pressure" or "determined pressure" may include any value representing pressure, such as an electrical potential, a resistance value, a multi-bit digital number, or the like. For example, a pressure transducer used to measure pressure in a pump control chamber may output an analog electrical potential, resistance, or other indication representing the pressure in the pump control chamber. The raw output from the transducer may be used as the measured pressure and / or some modified form of output, such as a digital number generated using the analog output from the transducer, psi or other value generated based on the transducer output, or the like. The same applies to other values, such as a determined volume, but not necessarily in a particular format, such as cubic centimeters. Alternatively, a determined volume may include any value representing volume and may be used, for example, to generate an actual volume, for example, in cubic centimeters.

[0206] In an embodiment of a fluid management system ("FMS") technique for determining the volume delivered by the pump, pressure equalization upon opening of valve X2 is assumed to occur in an adiabatic system. Thus, Equation 3 below provides the relationship between the volumes of the reference chamber system before and after pressure equalization:

[0207] Vrf=Vri(Pf / Patm) -(1 / γ) (3) where Vrf is the final (post-equalization) volume of the reference chamber system, including the volume of the reference chamber, the volumes of lines L2 and L3, and the volume adjustment resulting from the movement of the "piston" that can move to the left or right of X2 after opening, Vri is the initial (pre-equalization) volume of the reference chamber and lines L2 and L3 with the "piston" positioned at valve X2, Pf is the final equalization pressure after valve X2 opens, and Patm is the initial pressure in the reference chamber before valve X2 opens (atmospheric pressure in this example). Similarly, Equation 4 gives the relationship between the volumes of the control chamber system before and after pressure equalization.

[0208] Vdf=Vdi(Pf / Pdi) -(1 / γ) (4) where Vdf is the final volume of the control chamber system including the volume of the control chamber, the volume of lines L0 and L1, and the volume adjustment resulting from the movement of the "piston" which can move to the left or right of valve X2 after it opens; Vdi is the initial volume of the control chamber and lines L0 and L1 with the "piston" positioned at valve X2; Pf is the final pressure after valve X2 opens; and Pdi is the initial pressure in the control chamber before valve X2 opens.

[0209] The volumes of the reference and control chamber systems change by the same absolute amount after valve X2 is opened and pressures are equalized, but with different signs, as shown in Equation 5 (e.g., because the change in volume is caused by the movement of the "piston" to the left or right when valve X2 opens).

[0210] ΔVr=(-l)ΔVd(5) (Note that the volume change in the reference and control chambers is due only to the movement of the virtual pistons; the reference and control chambers do not actually change volume during the equalization process under normal conditions.) Also, using the relationship from Equation 3, the volume change of the reference chamber system is given by:

[0211] ΔVr=Vrf-Vri=Vri(-1+(Pf / Patm) -(1 / γ) ) (6) Similarly, using equation 4, the change in volume of the control room system is given by:

[0212] ΔVd=Vdf-Vdi=Vdi(-1+(Pf / Pdi) -(1 / γ)) (7) With Vri known and Pf and Patm measured or known, ΔVr can be calculated, which is assumed to be equal to (-)ΔVd according to Equation 5. Therefore, Vdi (the volume of the control chamber system before pressure equalization with the reference chamber) can be calculated using Equation 7. In this embodiment, Vdi represents the volume of the control chamber and lines L0 and L1, where L0 and L1 are fixed and known quantities. Subtracting L0 and L1 from Vdi yields the volume of the control chamber alone. Using Equation 7 above, for example, the change in volume of the control chamber can be determined both before (Vdi1) and after (Vdi2) pump action (e.g., at the end of a fill cycle and the end of a drain cycle), thus providing a measure of the volume of fluid delivered by (or taken up by) the pump. For example, if Vdi1 is the volume of the control chamber at the end of the fill stroke and Vdi2 is the control chamber volume at the end of the subsequent delivery stroke, the volume of fluid delivered by the pump can be estimated by subtracting Vdi1 from Vdi2. Because this measurement is based on pressure, the volume determination can be made for nearly any position of the membrane 15 / pump control region 1482 within the pump chamber 181, whether for a full or partial pump stroke. However, measurements made at the end of the fill stroke and end of the delivery stroke can be achieved with little or no effect on pump operation and / or flow rate.

[0213] One aspect of the present invention includes techniques for identifying pressure measurements used to determine volume for a control chamber and / or for other purposes. For example, pressure sensors can be used to detect pressure in the control chamber and the reference chamber, but the detected pressure values ​​may change depending on the opening and closing of valves, the introduction of pressure into the control chamber, venting the reference chamber to atmospheric pressure or other reference pressure, etc. Also, in one embodiment, because an adiabatic system is assumed to exist between the control chamber and the reference chamber before and after pressure equalization, identifying appropriate pressure values ​​measured closely in time can help reduce errors (e.g., because a shorter time elapsed in a pressure measurement can reduce the amount of heat exchanged in the system). Therefore, the measured pressure values ​​may need to be carefully selected to help ensure that the appropriate pressure is used to determine the volume delivered by a pump or the like.

[0214] As mentioned above, L3 in FIG. 43 can have a valve X3 leading to a vent. In some embodiments, this vent can communicate with atmosphere, or in other embodiments, with another reference pressure. In some embodiments, this vent can be connected to control chamber 171B via a valve so that the control chamber can be vented (see, for example, FIG. 38). In prior devices, the vent was used to bring control chamber 171B from negative pressure after the fill stroke to ambient pressure before positively pressurizing control chamber 171B. This allows control chamber 171B to a higher starting pressure before being connected to pressure source 84, thus minimizing pressure depletion in the positive pressure source or reservoir 84. As a result, the pump feeding the positive pressure reservoir needs to be operated less frequently.

[0215] However, it has been determined that it may be advantageous in some scenarios to subsequently vent the already positively pressurized control chamber 171B to a lower pressure before later positively repressurizing the chamber for FMS measurements. While this additional step requires additional work (e.g., pump run time) to maintain pressure source 84 at its pressure setpoint, it can be done to help mitigate any possible undesirable effects from backpressure (e.g., due to blockage or partial blockage of the line leading to or from the associated pump chamber). Furthermore, this can help improve the overall accuracy of volumetric measurements and fluid calculations. One possible reason for this is that pump chamber outlet valve 190 (in this case, a pneumatically actuated membrane valve) may not close efficiently when control chamber 171B remains positively pressurized.

[0216] In some embodiments, the control system 16 of the cycler 14 can vent the control chamber 171B before performing a measurement to determine the delivered or filled fluid volume. Additionally, in some embodiments, the control system 16 of the cycler 14 can vent the first control chamber 171B before performing a pumping operation with a second control chamber included in the installed cassette 24.

[0217] 43, this venting or backpressure relief may be achieved by opening valves X2 and X3 and closing valve X1. Thus, control chamber 171B may be positioned to communicate with the vent through reference chamber 174. Of course, in other embodiments, control chamber 171B may be positioned to communicate more directly with the vent. For example, an additional valve associated with the fluid path directly communicating with the vent may be included. Any other suitable configuration may also be used.

[0218] In some embodiments, the control chamber 171B can be vented by placing the control chamber 171B in fluid communication with the vent for a suitable or predetermined period of time. In other embodiments, to control the venting of the control chamber 171B, the control system 16 of the cycler 14 can use data from a pressure sensor associated with one or both of the control chamber 171B or the reference chamber 174 (or located in a position fluidly connectable to the control chamber, e.g., a pressure distribution module). In such embodiments, the data from the pressure sensor can be used to determine whether the control chamber 171B is sufficiently vented. Once the control chamber 171B is determined to be sufficiently vented, the control system 16 of the cycler 14 can close the appropriate valve to isolate the control chamber 171B from the vent. The pressure in the control chamber 171B does not necessarily have to perfectly equalize with the pressure at the vent for the control system 16 to determine that the control chamber 171B is sufficiently vented.

[0219] In some embodiments, to relieve backpressure within control chamber 171B, control chamber 171B can instead be exposed to a negative pressure source for an appropriate or predetermined period of time. In such embodiments, control chamber 171B can be placed in communication with pressure source 84. In the example embodiment shown in FIG. 43, this can be accomplished by opening valve X1 and closing at least valve X3. In the case of a positively pressurized control chamber 171B, the pressure source to which control chamber 171B is connected can be a negative pressure source. In some embodiments, control system 16 of cycler 14 may only open the valve to the negative pressure source for a short period of time. The short period can be sufficient time to allow the pressure within control chamber 171B to be within a predetermined range of a predetermined value (in an example, this can be approximately atmospheric pressure) before it can equalize with the pressure source. In other embodiments, valve X1 can be adjusted to achieve the same effect. If it is a variable valve, its orifice opening can be adjusted by a controller, and if it is a binary valve, the controller can adjust the rate and magnitude of pressure delivery across the valve, for example, using pulse width modulation.

[0220] For purposes of illustration, FIG. 44 shows a plot of exemplary pressure values ​​for the control and reference chambers from a time before valve X2 opens to some time after valve X2 opens to allow the pressures in the chambers to equalize. In this exemplary embodiment, the pressure in the control chamber is higher than the pressure in the reference chamber before equalization; however, it should be understood that the control chamber pressure may be lower than the reference chamber pressure before equalization in some configurations, such as during and / or at the end of the fill stroke. Also, while the plot in FIG. 44 shows a horizontal line marking the equalization pressure, it should be understood that this line is shown for clarity only. The equalization pressure is generally unknown before valve X2 opens. In this embodiment, pressure sensors detect pressure at a rate of approximately 2000 Hz for both the control and reference chambers, although other suitable sampling rates can be used. Before valve X2 opens, the pressure in the control and reference chambers is approximately constant, and no air or other fluid is introduced into the chambers. Therefore, valves X1 and X3 are generally closed before valve X2 opens. Additionally, valves leading into the pump chamber, such as valve ports 190 and 192, can be closed to block the effects of pressure fluctuations in the pump chamber, liquid supply, or liquid outlet.

[0221] First, the measured pressure data is processed to identify initial pressures, i.e., Pd and Pr, for the control and reference chambers. In one exemplary embodiment, the initial pressures are identified based on an analysis of a 10-point sliding window used on the measured pressure data. This analysis involves generating a best-fit line for the data within each window (or set), e.g., using least squares techniques, and determining the slope of the best-fit line. For example, each time a new pressure is measured for the control or reference chamber, a least-squares fit line can be determined for a data set including the most recent measurement and nine previous pressure measurements. This process can be repeated for several sets of pressure data, and a determination can be made as to when the slope of the least-squares fit line first becomes negative (or non-zero) and continues to become more negative (or deviate from a zero slope) for subsequent data sets. The point at which the least-squares fit line begins to have a suitable, increasing, non-zero slope can be used to identify the initial pressure of the chamber, i.e., the pressure before valve X2 is opened.

[0222] In one embodiment, the initial pressure values ​​for the reference and control chambers can be determined to be at the end of five consecutive data sets, where the slope of the best-fit line for those data sets increases from the first data set to the fifth data set, with the slope of the best-fit line for the first data set initially being non-zero (i.e., the slope of the best-fit line for data sets preceding the first data set is zero or not sufficiently non-zero). For example, the pressure sensor can sample every 1 / 2 millisecond (or other sampling rate) starting at a time before valve X2 opens. Each time a pressure measurement is made, cycler 14 can acquire the latest measurement along with the previous nine measurements and generate a best-fit line for the 10 data points in the set. When the next pressure measurement is taken (e.g., 1 / 2 millisecond later), cycler 14 can acquire the measurement along with the nine previous measurements and again generate a best-fit line for the 10 points in the set. This process can be repeated, and the cycler 14 can determine that when the slope of the best-fit line for a set of ten data points first becomes non-zero (or is otherwise suitably sloped), for example, the slope of the best-fit line for five subsequent sets of ten data points increases with each subsequent data set. To identify the predetermined pressure measurement to use, one technique is to select the third measurement in the fifth data set (i.e., the fifth data set for which the best-fit line is found to increase with a consistent slope and in which the first measurement is the earliest pressure measurement obtained in time) as the measurement to be used as the initial pressure for the control or reference chamber, i.e., Pd or Pr. This selection was made using an empirical method, for example, by plotting the pressure measurements and then selecting the point that best represents the point at which the pressure began the equalization process. Of course, other techniques can be used to select the appropriate initial pressure.

[0223] In one exemplary embodiment, it can be verified that the times at which the selected Pd and Pr measurements were taken were within a desired time threshold, e.g., within 1-2 milliseconds of each other. For example, if the control chamber pressure and reference chamber pressure are analyzed using the techniques described above to identify a pressure measurement (and therefore a time) immediately before pressure equalization begins, the times at which the pressures were measured should be relatively close to each other. If not, there may have been an error or other fault condition that invalidated one or both of the pressure measurements. By verifying that the times at which Pd and Pr occurred were appropriately close to each other, the cycler 14 can verify that the initial pressure was properly identified.

[0224] To determine when the pressures in the control chamber 171B and the reference chamber 174 have equalized so that the measured pressures for the chambers can be reliably used to determine the pump chamber volume, the cycler 14 can analyze data sets including a series of data points from pressure measurements for both the control chamber and the reference chamber, find a best-fit line for each of the data sets (e.g., using least squares), and determine when the slopes of the best-fit lines for the data set for the control chamber 171B and the data set for the reference chamber 174 are initially suitably similar to each other, e.g., both slopes have values ​​close to zero or within a threshold of each other. When the slopes of the best-fit lines are similar or close to zero, the pressures can be determined to have equalized. The first pressure measurement for either data set can be used as the final equalization pressure, i.e., Pf. In one exemplary embodiment, it was found that pressure equalization generally occurs within about 200 to 400 milliseconds after valve X2 is opened, with the majority of equalization occurring within about 50 milliseconds. Thus, the pressures in control chamber 171B and reference chamber 174 can be sampled approximately 400 to 800 or more times during the entire equalization process, from the time before valve X2 is opened until equalization is achieved.

[0225] In some cases, it may be desirable to improve the accuracy of control chamber 171B volume measurements using alternative FMS techniques. Substantial differences in temperature between the liquid being pumped and the control and reference chamber gases can introduce significant errors into calculations based on the assumption that pressure equalization occurs adiabatically. Waiting to perform a pressure measurement until sufficient pressure equalization between the control and reference chambers 171B and 174 can result in excessive heat transfer. In one embodiment of the present invention, pump chamber volume can be determined using pressure values ​​in the pump chamber 181 and reference chamber that are not substantially equivalent to each other, i.e., measured before complete equalization occurs.

[0226] In one embodiment, by measuring the chamber pressure over the entire equalization period, from the opening of valve X2 through full pressure equalization, and selecting a sampling point during the equalization period for the adiabatic calculation, heat transfer can be minimized and adiabatic calculation errors can be reduced. In one embodiment of an APD system, the measured chamber pressure obtained before full pressure equalization between the control chamber 171B and the reference chamber 174 can be used to determine the pump chamber 181 volume. In one embodiment, these pressure values ​​can be measured approximately 50 milliseconds after the chambers are first fluidly connected and equalization begins. As discussed above, in one embodiment, full equalization can occur approximately 200 to 400 milliseconds after valve X2 is opened. Therefore, the measured pressure can be obtained at a time point after valve X2 is opened (or equalization begins), which is approximately 10% to 50% of the entire equalization period or less. In other words, the measured pressure can be taken when 50%-70% of the pressure equalization has occurred (i.e., the reference chamber 174 and pump chamber 181 pressures have changed by approximately 50%-70% of the difference between the initial chamber pressure and the final equalization pressure). Using a computer-enabled controller, a substantial number of pressure measurements in the control and reference chambers can be taken, stored, and analyzed during the equalization period (e.g., 40-100 individual pressure measurements). Of the time points sampled during the first 50 milliseconds of the equalization period, a theoretically optimized sampling for performing adiabatic calculations is used. (For example, see FIG. 44, where the optimized sampling point occurs approximately 50 milliseconds after valve X2 opens.) The optimized sampling point occurs early enough after valve X2 opens to minimize heat transfer between the gas volumes of the two chambers, but not so early as to introduce significant error in the pressure measurement due to pressure sensor characteristics and valve actuation delays. However, as shown in FIG. 44, the pressures in the pump and reference chambers may not be substantially equal to each other at this point, and therefore equalization may not be complete.(In some cases, it may be technically difficult to obtain a reliable pressure measurement immediately after valve X2 opens due to, for example, inherent inaccuracies in pressure sensors, the time required to fully open valve X2, and the rapid initial change in pressure in either control chamber 171B or reference chamber 174 immediately after valve X2 opens.)

[0227] During pressure equalization, when the final pressures to the control chamber 171B and the reference chamber 174 are not the same, Equation 2 becomes: PriVri γ +PdiVdi γ =Constant=PrfVrf γ +PdfVdf γ (8) where Pri = pressure in the reference chamber before opening valve X2, Pdi = pressure in the control chamber before opening valve X2, Prf = final reference chamber pressure, and Pdf = final control chamber pressure.

[0228] An optimization algorithm can be used to select the point during the pressure equalization period at which the difference between the absolute values ​​of ΔVd and ΔVr is minimized (or below a desired threshold) over the equalization period. (In an adiabatic process, this difference should ideally be zero, as shown by Equation 5. In Figure 104, the point at which the difference between the absolute values ​​of ΔVd and ΔVr is minimized occurs at the 50 ms line, marked "Point at which final pressure is determined.") Initially, pressure data can be collected from the control and reference chambers at multiple points j=1 to n between the opening of valve X2 and the final pressure equalization. Because Vri, the fixed volume of the reference chamber system before pressure equalization, is known, subsequent values ​​for Vrj (the reference chamber system volume at sampling point j after valve X2 is opened) can be calculated using Equation 3 at each sampling point Prj along the equalization curve. For each such value of Vrj, a value for ΔVd can be calculated using Equations 5 and 7, such that each value of Vrj yields an estimate for Vdij, Vdi, the volume of the control chamber system before pressure equalization. Using each value of Vrj and its corresponding value of Vdij, and using Equations 3 and 4, the difference in absolute values ​​of ΔVd and ΔVr can be calculated at each pressure measurement point along the equalization curve. The sum of the squares of these differences provides a measure of the error in the calculated value of Vdi between pressure equalization for each value of Vrj and its corresponding Vdij. Denoting the reference chamber pressure that results in the minimum sum of the squared differences of |ΔVd| and |ΔVr| as Prf and its associated reference chamber volume as Vrf, the data points Prf and Pdf corresponding to Vrf can be used to calculate an optimized estimate of Vdi, i.e., the control room system initial volume.

[0229] One way to find the location on the equalization curve that captures the optimized values ​​for Pdf and Prf is as follows. 1) Collect a series of pressure data sets from the control and reference chambers, starting just before opening valve X2 and ending with Pr and Pd approaching equal values. If Pr is the first reference chamber pressure captured, then subsequent sampling points in diagram 104 are designated Prj = Pr1, Pr2, ... Prn.

[0230] 2) For each Prj after Pri, calculate the corresponding ΔVrj using Equation 6 (where j represents the jth pressure data point after Pri). ΔVrj=Vrj-Vri=Vri(-1+(Prj / Pri) -(1 / γ) ) 3) For each such ΔVrj, calculate the corresponding Vdij using Equation 7. for example, ΔVr1=Vri*(-1+(Pr1 / Pri) -(1 / γ) ) ΔVd1=-ΔVr1 therefore, Vdi1=ΔVd1 / (-1+(Pd1 / Pdi) -(1 / γ) ) Vdin = ΔVdn / (-1 + (Pdn / Pdi) -(1 / γ) ) During pressure equalization, a set of n control chamber system initial volumes (Vdi1 to Vdin) can be calculated based on the set of reference chamber pressure data points Pr1 to Prn, and a time point (f) can be selected that results in an optimized measurement of the control chamber system initial volumes (Vdi) throughout the pressure equalization period.

[0231] 4) Using Equation 7, all ΔVdj,k are calculated for each of Vdi1 to Vdin using the control chamber pressure measurement value Pd for time points k=1 to n. For Vdi corresponding to Pr1, ΔVd1,1=Vdi1*(-1+(Pd1 / Pdi) -(1 / γ) ) ΔVd1,2=Vdi1*(-1+(Pd2 / Pdi) -(1 / γ) ) ΔVd1,n=Vdi1*(-1+(Pdn / Pdi) -(1 / γ) ) For Vdi corresponding to Prn, ΔVdn,l=Vdin*(-1+(Pd1 / Pdi) -(1 / γ) ) ΔVdn,2=Vdin*(-1+(Pd2 / Pdi) -(1 / γ) ) ΔVdn,n=Vdin*(-1+(Pdn / Pdi) -(1 / γ) ) 5) Take the sum of the squared errors between the absolute values ​​of ΔVr and ΔVdj,k.

[0232]

number

[0233] [S1 represents the sum of squared errors of |ΔVd|-|ΔVr| over all data points during the equalization period when the first data point Pr1 is used to determine Vdi from Vr1 and ΔVr, i.e., the initial volume of the control chamber system.]

[0234]

number

[0235] [S2 represents the sum of squared errors of |ΔVr| - |ΔVd| over all data points during the equalization period when the second data point Pr2 is used to determine Vdi from Vr2 and ΔVr, i.e., the initial volume of the control room system.]

[0236]

number

[0237] 6) The Pr data point between Pr1 and Prn that produces the least sum of squared errors S (or a value less than a desired threshold) from some step 5 then becomes the selected Prf, from which Pdf and an optimized estimate of Vdi, i.e., the control room initial volume, can be determined. In this example, Pdf occurs at or near the same time as Prf.

[0238] 7) The above procedure can be applied whenever an estimate of the control chamber volume is desired, but preferably at the end of each fill stroke and each delivery stroke. The difference between the optimized Vdi at the end of the fill stroke and the optimized Vdi at the end of the corresponding delivery stroke can be used to estimate the volume of liquid delivered by the pump.

[0239] Air Detection Another aspect of the present invention involves determining the presence of air in pump chamber 181 and, if so, the volume of air present. Such a determination can be important, for example, to help ensure that a priming procedure has been properly performed to remove air from cassette 24 and / or to help ensure that air is not delivered to the patient. In some embodiments, for example, when delivering fluid to a patient through lower opening 187 at the bottom of pump chamber 181, air or other gas trapped in the pump chamber can tend to remain within pump chamber 181 and be prevented from being pumped to the patient unless the volume of that gas is greater than the volume of the effective dead space of pump chamber 181. As described below, in accordance with an embodiment of the present invention, the volume of air or other gas contained in the pump chamber 181 can be determined, and the gas can be purged from the pump chamber 181 before the volume of the gas becomes greater than the volume of the effective dead space of the pump chamber 181.

[0240] Determining the amount of air in pump chamber 181 can be done at the end of the fill stroke, and therefore can be done without interrupting the pumping process. For example, at the end of the fill stroke, when membrane 15 and pump control region 1482 are pulled away from cassette 24, causing membrane 15 / region 1482 to contact the wall of control chamber 171, valve X2 can be closed and the reference chamber can be vented to atmospheric pressure, for example, by opening valve X3. Valves X1 and X3 can then be closed, fixing a virtual "piston" at valve X2. Valve X2 can then be opened, and the pressures in the control and reference chambers can be equalized, as described above when taking pressure measurements to determine the volume of the control chamber.

[0241] If there are no air bubbles in the pump chamber 181, the change in volume of the reference chamber, i.e., the change due to movement of the virtual "piston," determined using the known initial volume of the reference chamber system and the initial pressure in the reference chamber, will equal the change in volume of the control chamber determined using the known initial volume of the control chamber system and the initial pressure in the control chamber. (The initial volume of the control chamber may be known with the membrane 15 / control region 1482 in contact with the control chamber wall or with the spacer element 50 of the pump chamber 181.) However, if air is present in the pump chamber 181, the change in volume of the control chamber is actually distributed between the control chamber volume and the air bubbles in the pump chamber 181. As a result, the calculated change in volume for the control chamber using the known initial volume of the control chamber system will not equal the calculated change in volume for the reference chamber, thus signaling the presence of air in the pump chamber.

[0242] When there is air in the pump chamber 181, the initial volume Vdi of the control chamber system is actually equal to the sum of the volumes of the control chamber and lines L0 and L1 (called Vdfix) plus the initial volume of the air bubbles in the pump chamber 181 (called Vbi), as shown in Equation 9.

[0243] Vdi=Vbi+Vdfix(9) At the end of the filling stroke, the membrane 15 / control area 1482 is pressed against the wall of the control chamber. In the compressed state, the volume of any air space within the control chamber can be known very accurately, for example, due to the presence of grooves or other features in the control chamber wall and the volume of lines L0 and L1 (together, Vdfix). (Similarly, with the membrane 15 / control region 1482 pressed against the spacer element 50 of the pump chamber 181, the volume of the control chamber and lines L0 and L1 can be known accurately.) After the fill stroke, the volume of the control chamber system is tested using a positive control chamber precharge. Any difference between this tested volume and the tested volume at the end of the fill stroke can indicate the volume of air in the pump chamber. Substituting Equations 9 through 7, the change in volume of the control chamber, ΔVd, is given by:

[0244] ΔVd=(Vbi+Vdfix)(-1+(Pdf / Pdi) -(1 / γ) )(10) ΔVr can be calculated from Equation 6, and from Equation 5, ΔVr = (-1)ΔVd Since it is known, Equation 10 can be rewritten as follows:

[0245] (-l)ΔVr=(Vbi+Vdfix)(-1+(Pdf / Pdi) -(1 / γ) )(11) And again, it can be rewritten as follows:

[0246] Vbi = (-1)ΔVr / (-l + (Pdf / Pdi) -(1 / γ) )-Vdfix(12) Thus, using Equation 12, the cycler 14 can determine whether there is air in the pump chamber 181 and the approximate volume of the bubble. This bubble volume calculation can be performed, for example, when it is found that the absolute values ​​of ΔVr (as determined from Equation 6) and ΔVd (as determined from Equation 7 using Vdi=Vdfix) are not equal to one another. That is, if there is no air in the pump chamber 181, Vdi should be equal to Vdfix, and therefore the absolute value of ΔVd given by Equation 7 using Vdfix instead of Vdi will be equal to ΔVr.

[0247] After the fill stroke is complete and air is detected according to the method described above, it can be difficult to determine whether the air is located on the pump chamber side or the control side of the membrane 15. There may be air bubbles in the liquid being pumped, or there may be residual air on the control (air pressure) side of the pump diaphragm 15 due to a condition during pumping (e.g., a blockage) that resulted in an incomplete pump stroke and incomplete filling of the pump chamber. At this point, an adiabatic FMS measurement with a negative pressure pump chamber precharge can be performed. If this FMS volume matches the FMS volume with a positive pressure precharge, the membrane can move freely in both directions, suggesting that the pump chamber is only partially filled (perhaps due to a blockage, for example). If the value of the negative pressure pump chamber precharge FMS volume is equal to the nominal control chamber air volume when the membrane 15 / region 1482 contacts the inner wall of the control chamber, it can be concluded that there are air bubbles in the fluid on the pump chamber side of the flexible membrane.

[0248] Polytropic FMS for pump delivery volume measurement. 1A can determine the volume of fluid delivered in the various lines of system 10 without the use of flow meters, weigh scales, or other direct measurements of fluid volume or weight. For example, in one embodiment, the volume of fluid moved by a diaphragm pump, such as an air-driven diaphragm pump including cassette 24, can be determined based on pressure measurements of the gas used to drive the pump.

[0249] In one embodiment, determining the volume is accomplished by a process referred to herein as the two-chamber fluid measurement system (two-chamber FMS) process. The volume of fluid pumped by a diaphragm pump can be calculated from the change in volume of the pneumatic chamber on either side of the diaphragm. The volume of the pneumatic chamber can be measured at the end of each fill and delivery stroke, and the difference in volume between subsequent measurements is the volume of fluid moved by the pump.

[0250] The volume of the pneumatic or first chamber is measured by a two-chamber FMS process that includes closing liquid valves in and out of a diaphragm pump, isolating the first chamber from a second (reference) chamber of known volume, precharging the first chamber to a first pressure while precharging the second chamber to a second pressure, then fluidly connecting the two chambers, and recording at least the initial and final pressures in each chamber as the pressures equalize. The volume of the first chamber can be calculated from at least the initial and final pressures and the known volume of the second chamber.

[0251] If the first chamber is precharged to a pressure greater than the pressure in the second chamber, the two-chamber FMS process is called positive pressure FMS or +FMS. If the first chamber is precharged to a pressure less than the pressure in the second chamber, the two-chamber FMS process is called negative pressure FMS or -FMS. Referring now to Figure 45, the first chamber is the control chamber 6171 and the second chamber is the reference chamber 6212.

[0252] The form of the algorithm for calculating the first chamber volume may depend on the heat transfer characteristics of the first and second chambers and the fluid lines connecting them. The amount of heat transfer between the structure and the gas during equalization affects the pressure in both the first and second chambers during and after equalization. During equalization, the gas in the higher-pressure chamber expands toward the other chamber. This expanding gas cools to a lower temperature and therefore lower pressure. The temperature drop and pressure loss of the expanding gas may be slowed or reduced by heat transfer from the hotter structure. At the same time, the gas in the initially low-pressure chamber is compressed during equalization. The temperature of this compressed gas increases with its pressure. The heating and pressure increase of the compressed gas may be slowed or reduced by heat transfer from the cooler structure.

[0253] The relative importance of heat transfer between the structure (chamber walls, solid material within the chamber) and the gas is a function of the mean hydraulic diameter of the chamber, the thermal diffusivity of the gas, and the duration of the equalization process. In one example, the two volumes are filled with a heat-absorbing material, such as a foam or other matrix, that provides sufficient surface area and thermal mass so that the gas temperature is constant within each chamber during pressure equalization, allowing the expansion and compression processes to be modeled as isothermal. In another example, the two chambers are sized and shaped to provide negligible heat transfer, so that the expansion and compression processes can be modeled as adiabatic. In another example, the shape and size of the control chamber 6171 varies from measurement to measurement. In measurements after the fill stroke, if the control chamber 6171 is small and all of the gas is relatively close to the chamber walls 6170 or membrane 6148, heat transfer between the gas and the structure is significant. In measurements after the delivery stroke, the control chamber 6171 is large and open, so much of the gas is relatively isolated from the chamber walls 6170 or diaphragm 6148, and heat transfer to the gas is negligible. In measurements after the partial stroke, heat transfer between the structure and the gas is significant, but not enough to ensure a constant temperature. In all of these measurements, the expansion and compression processes can be modeled as polytropic, and the relative importance of heat transfer can change from measurement to measurement. A polytropic model can accurately model the equalization process for all geometries and capture the effects of different levels of heat transfer in the first and second chambers. A more detailed model of the equalization process more accurately determines the volume of the first chamber from knowledge of the pressure and volume of the second chamber.

[0254] This section describes the algorithm for calculating the volume of the first chamber 6171 for a polytropic two-chamber FMS process. The first subsection describes a two-volume FMS or two-chamber FMS process for an exemplary arrangement of volumes, pressure sources, valves, and pressure sensors. The next subsection conceptually describes the polytropic FMS algorithm for data from a +FMS process, followed by the exact equations for calculating the first volume from the pressure data. The next subsection presents the concepts and equations for the polytropic FMS algorithm for data from a -FMS process. The final subsection presents the process for calculating the volume of the first chamber 6171 using either set of equations.

[0255] The described model can be applied to any system or device using a pneumatically actuated diaphragm pump. The system components include a diaphragm pump having at least one chamber inlet or outlet with a valved connection to either a fluid source or a fluid destination; a pneumatic control chamber separated from the pump chamber by a diaphragm that provides positive or negative pressure to the pump chamber for fluid delivery or filling, the pneumatic control chamber having a valved connection to a reference chamber of known volume and a positive or negative pressure source; and a controller that controls the system's valves and monitors the air pressure in the control and reference chambers. An example system is shown schematically in Figure 45, although the specific configuration of the inlets, outlets, and fluid and pneumatic conduits and valves can vary somewhat from this illustration. The following description uses a peritoneal dialysis cycler and pump cassette as examples, but the invention is in no way limited to this particular application.

[0256] Hardware for the two-chamber FMS process Referring now to Figure 45, Figure 45 schematically presents the elements of a cycler and cassette 624 involved in a two-chamber FMS process. Cassette 624 includes two liquid valves 6190, 6192, which are fluidly connected to a liquid source 6193 and a liquid outlet 6191. Cassette 624 includes a diaphragm pump in which a variable liquid volume pump chamber 6181 is separated from a control chamber 6171 by a flexible membrane 6148. The volume of control chamber 6171 is defined by membrane 6148 and chamber wall 6170. Control chamber 6171 is the first chamber of unknown volume described above.

[0257] The control line 6205 also leads to a connecting valve 6214, which communicates with a reference line 6207 and a reference chamber 6212 (e.g., a space suitably configured to perform measurements as described below). The reference chamber 6212 is a second chamber having a known volume as described above. The reference chamber 6212 also communicates with an outlet line 6208 having a second valve 6216 that opens to a vent 6226 to atmospheric pressure. In another example, the vent 6226 can be a reservoir controlled to a desired pressure by one or more pneumatic pumps, pressure sensors, and a controller. The valves 6220, 6214, and 6216 can be independently controlled by the controller 61100.

[0258] A pressure source 6210 is selectively connected to a control chamber 6171 via lines 6209 and 6205. The pressure source 6210 may include one or more separate reservoirs maintained at different designated pressures by one or more pneumatic pumps. Each pneumatic pump may be controlled by a controller 61100 to maintain a designated pressure in each reservoir as measured by a pressure sensor. A first valve 6220 may control the fluid connection between the pressure source 6210 and the control chamber 6171. The controller 61100 may selectively connect one of the reservoirs in the pressure source 6210 to line 6209 to control the pressure in the control chamber as measured by a pressure sensor 6222. In some examples, the controller 1100 may be part of a larger control system in an APD cycler.

[0259] The control chamber 6171 is connected to a control pressure sensor 6222 via line 6204. A reference pressure sensor 6224 can be connected to the reference chamber 6212 via line 6203. The pressure sensors 6222, 6224 can be electromechanical pressure sensors that measure absolute pressure, such as the MPXH6250A manufactured by Freescale Semiconductors of Japan. The control pressure sensor 6222 and the reference pressure sensor 6224 are connected to the controller 61100, which records the control and reference pressures for subsequent volume calculations. Alternatively, the pressure sensors 6222, 6224 can be relative pressure sensors that measure the pressure in the control and reference chambers relative to ambient pressure, and the controller 61100 can include an absolute pressure sensor that measures ambient pressure. The controller 61100 can combine the relative pressure signals from sensors 6222, 6224 and the absolute ambient pressure sensor to calculate the absolute pressure in the control chamber 6171 and reference chamber 6212, respectively.

[0260] The controller 61100 can control the valves and other components of the FMS hardware shown in FIG. 45 to run a two-chamber FMS process, measure the resulting pressure in the control chamber 6171 and the reference chamber 6212, and calculate the volume of the control chamber 6171. The controller 61100 can be a single microprocessor or multiple processors. In one example, the pressure signal is received by an AD board and buffered before being passed to the 61100 controller. In another example, a field programmable gate array (FPGA) can handle all I / O between the controller 61100 and the valves and sensors. In another example, the FPGA can filter, store, and / or process the pressure data to calculate the volume of the control chamber.

[0261] Two-chamber FMS process in an APD cycler Referring now to the pressure versus time plot in FIG. 46 and elements of FIG. 45, an exemplary pumping and measurement process is set forth in the plot of control chamber pressure 6300 and reference chamber pressure 6302 versus time. As described above, after closing inlet valve 6192 and opening outlet valve 6190, the chamber pressure is controlled relative to positive pressure valve 6305, which forces fluid out of pump chamber 6181 during delivery stroke 6330. At the end of delivery stroke 6330, the outlet fluid valve is closed and an FMS process can occur to measure the volume of control chamber 6171. An FMS process, as described elsewhere, can consist of bringing control chamber pressure 6330 to pre-charge pressure 6307 and allowing a pressure stabilization period 6338 followed by an equalization process 6340. In other examples, control chamber pressure 6330 can be returned to approximately atmospheric pressure before rising to pre-charge pressure 6307. At the end of the equalization process 6340, the reference chamber pressure 6302 and possibly the control chamber pressure 6300 may be returned to approximately atmospheric values.

[0262] The fill stroke 6320 occurs after opening the inlet valve 6192, causing the control chamber pressure 6300 to become negative pressure 6310 while the reference chamber remains at approximately atmospheric pressure, or a measured constant pressure. The negative pressure draws fluid into the pump chamber 6181. At the end of the fill stroke 6320, the inlet valve 6192 closes and a +FMS process can occur to determine the volume of the control chamber 6171. In some embodiments, a -FMS process can occur after the +FMS process. The -FMS process can include pre-charging the control chamber to negative pressure 6317 to allow for pressure stabilization 6342 and ultimately an equalization process 6345. The control chamber volume determined from the -FMS process can be compared to the control chamber volume determined from the +FMS process to determine whether there is a volume of air or gas in the pump chamber 6181. (For example, if the pump chamber includes an air trap with ribs or standoffs on the pump chamber rigid wall, air can accumulate between the standoffs and the diaphragm at full range of motion can be prevented from compressing by the standoffs, and the air cannot be detected by the +FMS process alone.) ) In one example, the -FMS process occurs after the delivery stroke 6330.

[0263] The +FMS and -FMS processes are described in more detail with reference to the flowchart in Figure 47, the elements in Figure 46, and the pressure versus time plots in Figures 48A and 48B. The two-chamber FMS process begins at step 6410, where the position of the membrane 6148 is fixed. The position of the membrane 6148 can be fixed by closing both hydraulic valves 6190, 6192. In some examples, if air bubbles are present in the liquid, the position of the membrane 6148 will change as the control chamber pressure changes. However, the volume of incompressible liquid between the hydraulic valves 6190, 6192 is fixed. The two-chamber FMS process generally measures the volume of air or gas on both sides of the membrane 6148, so that any air bubbles in the pump chamber 6181 on the liquid side of the membrane 6148 are included in the measured volume of the control chamber 6171.

[0264] In step 6412, the control chamber 6171 is fluidly isolated from the reference chamber 6212 by closing the connecting valve 6214. Then, in step 6412, the reference chamber 6212 and the control chamber 6171 are fluidly isolated from each other. In an embodiment, in step 6424, the reference chamber 6212 is connected to the vent 6226 by opening the second valve 6216. The controller 61100 keeps the second valve 6216 open until the reference pressure sensor 6224 indicates that the reference pressure has reached ambient pressure. Alternatively, the controller 61100 can control the second valve 6216 to achieve a desired initial reference pressure in the reference chamber 6212, as measured by the reference pressure sensor 6224. Alternatively, the connecting valve 6214 can be closed and the second valve 6216 opened before the FMS process begins. In step 6428, once the desired pressure in the reference chamber 6212 is achieved, the second valve 6216 is closed, thereby fluidly isolating the reference chamber 6212. The reference chamber steps 6424 and 6428 can be programmed to occur simultaneously with the control chamber steps 6414 and 6418.

[0265] In step 6414, control chamber 6171 is pressurized to a desired pressure by connecting control chamber 6171 to pressure source 6210 by opening first valve 6220. Controller 61100 monitors the pressure in control chamber 6171 via pressure sensor 6222 and controls first valve 6220 to reach the desired pre-charge pressure. The desired pre-charge pressure can be significantly above or significantly below the initial base pressure of reference chamber 6212. In one example, control chamber 6171 is pre-charged to a pressure of approximately 40 kPa above the base pressure for a +FMS process. In another example, control chamber 6171 is pre-charged to a pressure of approximately 40 kPa below the base pressure for a -FMS process. In other embodiments, the pre-charge pressure can be any pressure within a range of 10% to 180% of the initial base pressure.

[0266] The controller 61100 closes the first valve 6220 in step 6418 and monitors the pressure in the control chamber 6171 via the pressure sensor 6222. The pressure in the control chamber 6171 may move toward ambient pressure during step 6418 as the gas thermally equalizes with the control chamber walls 6170 and membrane 6148. A large change in pressure during step 6418 may indicate an air or liquid leak that invalidates the measurement. If the rate of pressure change exceeds a predetermined allowable rate, the two-chamber FMS process may be aborted or the calculated volume of the control chamber 6171 may be discarded. After a delay from the pressurization step 6414, the rate of pressure change may be checked to allow the gas in the control chamber 6171 to approach thermal equilibrium with the boundaries 6172, 6148 of the control chamber 6171. In one example, the maximum allowable rate of pressure change during step 6418 is 12 kPA / sec. If the rate of pressure change exceeds this predetermined value, the two-chamber FMS process can be aborted and restarted. In another embodiment, the maximum allowable rate of pressure change is a function of, i.e., varies based on, the calculated control chamber volume. In one example, the maximum allowable pressure change is 3 kPA / sec for a 25 ml volume and 25 kPA / sec for a 2 ml volume. In one example, the FMS process can be completed regardless of the leak rate introduced into the calculated volume of the control chamber 6171. If the measured rate of pressure change exceeds the allowable limit for the calculated control chamber volume, the calculated volume can be discarded and the FMS process can be restarted.

[0267] In step 6432, the controller 61100 opens the connecting valve 6214 between the two chambers, fluidly connecting the control chamber 6171 and the reference chamber 6212. The controller 61100 monitors the pressure in each chamber via pressure sensors 6222, 6224 as the pressures in the control chamber 6171 and the reference chamber 6212 equalize. The controller 61100 can record an initial pressure pair and at least one pressure pair at the end of equalization in step 6432. A pressure pair refers to a signal from the control pressure sensor 6222 and a signal from the reference pressure sensor 6224 recorded at approximately the same time. Step 6432 spans the linear period during which access valve 6214 opens to the point at which the pressures in control chamber 6171 and reference chamber 6212 are approximately equal.

[0268] In step 6436, the two-chamber FMS process is completed where the recorded pressure pairs are used to calculate the volume of the control chamber 6171. The calculation of the control chamber 6171 volume is described in more detail below.

[0269] The +FMS process is outlined as a pressure versus time plot in FIG. 48A. Reference numbers corresponding to the reference numbers of the steps in FIG. 47 are included to indicate where those steps appear in FIG. 48A. The pressure in the control chamber 6171 is plotted as line 6302. The pressure in the reference chamber is plotted as line 6304. The pressure versus time plot begins after steps 6410, 6412, 6424, and 6428 of FIG. 47 are completed. At this point, the pressure in the reference chamber 6212 is at the desired reference pressure 6312. The pressure in the control chamber 6171 starts at an arbitrary pressure 6306 and increases to a pre-charge pressure 6316 during step 6414. The arbitrary pressure 6306 may be the pressure in the control chamber 6171 at the end of a previous pumping operation. In another embodiment, the arbitrary pressure 6306 may be atmospheric pressure. During step 6418, the control chamber pressure 6302 may decrease. In step 6432 , the control chamber pressure 6302 and the reference chamber pressure 6304 equalize toward an equilibrium pressure 6324 .

[0270] The -FMS process is outlined as a pressure versus time plot in Figure 48B. The pressure in control chamber 6171 (Figure 45) is plotted as line 6302. The pressure in reference chamber 6312 (Figure 45) is plotted as line 6304. The horizontal time axis is divided into periods corresponding to process steps identified with the same reference numbers in Figure 47. The pressure versus time plot begins when the pressure in reference chamber 6212 (line 6302) is at the desired reference pressure 6312 and the pressure in control chamber 6171 (line 6304) is at an arbitrary pressure. During step 6414, the control chamber pressure 6302 is reduced to a negative pre-charge pressure 6317. The control chamber pressure 6302 may increase during step 6418 as the gas cooled by the sudden expansion of step 6414 is heated by the control chamber walls 6172, 6148. In step 6432, the control chamber pressure 6302 and the reference chamber pressure 6304 equalize toward the equilibrium pressure 6324.

[0271] Polytrope + FMS algorithm Referring now to FIG. 45, for illustrative purposes, the equalization process involves the fluid volumes of three separate structures: the control chamber 6171, the reference chamber 6212, and the manifold passages 6204, 6205, 6207, and 6209 connecting the two chambers 6171 and 6212. In one example, each structure has a significantly different hydraulic diameter and therefore a different level of heat transfer between the structure and the gas. In this example, the reference chamber 6212 has an approximately cubic shape with a hydraulic diameter of 3.3 cm. Heat transfer during the approximately 30 microsecond equalization process is negligible, and the gas within the reference chamber 6212 volume may be adiabatically compressed and can be modeled as such. In contrast, in the exemplary structure, the manifold passages 6204, 6205, 6207, and 6209 have hydraulic diameters of approximately 0.2 cm, which is about one-fifteenth the hydraulic diameter of the reference chamber 6212 volume. Heat transfer within the manifold passages 6204, 6205, 6207, and 6209 is high, and gas passing through these passages 6204, 6205, 6207, and 6209 is more likely to compress or expand isothermally at approximately the temperature of the manifold wall. The hydraulic diameter of the control chamber 6171 in this example has a minimum value of approximately 0.1 cm when the pump chamber 6181 is full of liquid at the end of the fill stroke and the control chamber 6171 is at its minimum volume. The hydraulic diameter of the control chamber 6171 in this example has a maximum value of approximately 2.8 cm when the pump chamber 6181 is delivering liquid and the control chamber 6171 is at its maximum volume. The expansion of the gas within the control chamber 6171 can be better modeled by a polytropic coefficient, which varies with the size of the control chamber 6171. If the control chamber 6171 volume is minimum and the expansion process is approximately isothermal, the polytropic coefficient can be set to approximately 1. If the control chamber 6171 is at its maximum and the expansion process is nearly adiabatic, the polytropic coefficient can be set approximately to the specific heat ratio (cp / cv), which is equal to 1.4 for air. For two-chamber FMS measurements during partial stroke, the expansion process occurs with significant heat transfer, but not enough to be isothermal. For partial stroke measurements, the polytropic coefficient can be set to a value between 1 and 1.4.Since the volume of the control room 6171 is the unknown quantity in this analysis, the polytropic coefficient for the control room 6171 can be based on an estimate of the control room 6171 volume.

[0272] Referring now to FIG. 49A , the gases within the structure of the control chamber 6510, the reference chamber 6520, and the manifold lines 6530, 6531 can be modeled as three gas masses 6512, 6532, 6522 that do not mix but expand, contract, and move throughout the structures 6510, 6520, 6530, 6531. Conceptually, for modeling purposes, these masses 6512, 6532, 6522 are each closed systems that can move, change size, and exchange energy with the structure, but masses cannot enter or leave the closed system. The closed system model is a well-understood concept in thermodynamics and fluid mechanics. These masses can also be referred to as the control chamber system 6512, the reference chamber system 6522, and the manifold or interconnecting line system 6532.

[0273] Based on a thermodynamic model of the three masses 6512, 6532, 6522, the volume of the control chamber 6510 can be calculated from the measured pressures of the control chamber 6510 and reference chamber 6520. The control chamber mass or gas 6512 is the gas that occupies the control chamber 6510 at the end of the equalization process. The reference chamber gas 6522 is the gas that occupies the reference chamber 6520 at the start of the equalization process. The manifold gas 6532 satisfies the structural equilibrium between the control chamber gas 6512 and the reference chamber gas 6522, including the connecting conduit between the control chamber gas and the reference chamber.

[0274] Then, from the initial conditions, pressure pairs, heat transfer assumptions, and constant total volume constraints for the three closed systems, the volumes and temperatures of the three closed systems 6512, 6532, 6522 can be calculated. Pressure equalization can be modeled by using different polytropic coefficients for each volume 6510, 6520, 6530, 6531 to capture the relative importance of heat transfer in each. The ideal gas and polytropic process equations for the three systems 6512, 6532, 6522 can be combined and collated to calculate the volume of the control chamber 6510. The following paragraphs describe the derivation of one or more sets of equations that allow for the calculation of the control chamber 6510 volume based on the pressure measured during the pressure equalization step (see 6432 in Figures 47 and 108A) of the FMS process.

[0275] +Closed system explanation for FMS The upper image in Figure 49A presents the positions of the three closed systems 6512, 6532, 6522 at the start of pressure equalization in the +FMS process. The lower image presents the positions of the three closed systems 6512, 6532, 6522 at the end of pressure equalization. During the equalization process, the positions of the closed systems 6512, 6532, 6522 lie between the two extremes presented in Figure 49A. As an example, neither the control room system 6512 nor the reference room system 6522 fulfills their respective structures. The following paragraphs present the closed systems 6512, 6532, 6522 in more detail.

[0276] The control chamber gas system 6512 is the gas that fills the control chamber 6510 after pressure equalization. Prior to pressure equalization, the control chamber gas system 6512 is compressed to a precharge pressure that is higher than the final equalization pressure and therefore does not occupy the entire control chamber 6510. The control chamber gas system 6512 can be modeled as expanding in a polytropic process during pressure equalization of the +FMS process, where pressure and volume are related by the following equation:

[0277] p f V cc nCC = constant In the formula, p fis the equalization pressure, and V cc is the volume of the control room 6510 and nCC is the polytropic coefficient for the control room 6510.

[0278] The reference gas system 6522 is the gas that occupies the entire reference volume 6520 before equalization. The reference gas system 6522 is compressed when the higher pressure gas in the control chamber 6510 expands, forcing the manifold gas system 6532 into the reference chamber 6520. In one example shown in FIG. 36, the reference chamber (shown as 174 in FIG. 36) is sufficiently open or devoid of internal features / elements so that the compression or expansion process during pressure equalization can be modeled as adiabatic. In this case, the polytropic coefficient (n) can be set approximately equal to the specific heat ratio of the gas present in the chamber. The pressure and volume of the reference chamber gas 6522 are related by the following equation:

[0279] p R0 V Ref nR = constant In the formula, p R0 is the initial reference pressure, and V Ref is the volume of the reference chamber, and nR is the specific heat ratio for the gas in the reference chamber (nR=1.4 for air). In another example, if the chamber 6520 is at least partially filled with a heat-absorbing material that provides near-isothermal expansion, such as open-cell foam, wire mesh, particles, etc., the polytropic coefficient (nR) for the reference chamber may have a value of approximately 1.0.

[0280] In the +FMS process, the conduit or manifold gas system 6532 occupies all of the volumes of the interconnection volumes 6530, 6531 and a portion 6534 of the control chamber 6510 before equalization. After equalization, the conduit gas system 6532 occupies the interconnection volumes 6530, 6531 and a portion of the reference volume 6520. The portion of the conduit gas system 6532 residing on the control chamber side of the valve 6540 of the interconnection volume 6530 is labeled herein as 6533. The portion of the conduit gas system 6532 residing on the reference chamber side of the valve 6540 of the interconnection volume 6531 is referred to as 6535. The portion of the conduit gas system 6532 residing within the control chamber 6510 before equalization is labeled herein as 6534. The portion of the conduit gas system 6532 residing within the reference chamber 6520 after equalization is referred to as 6536.

[0281] In one example, the interconnecting volumes 6530 and 6531 can be narrow passages, which provide high heat transfer and ensure that the conduit gas system 6532 within the volumes 6530 and 6531 is close to the temperature of the solid boundaries or walls of the passages. The temperature of the interconnecting volumes 6530, 6531 or the structure surrounding the manifold passages is referred to herein as the wall temperature (T w ) In another example, the temperature of the conduit gas system 6532 in volumes 6530, 6531 is, in part, a function of wall temperature. The portion of the conduit or manifold gas system in the control chamber 6534 can be modeled with the same temperature as the control chamber gas system 6512. The control chamber portion of the conduit gas system 6534 can be considered to expand in the same way and have the same temperature as the control chamber gas system 6512. The portion of the line or manifold gas system in the reference chamber 6536 can be modeled with a temperature that is, in part, a function of wall temperature. In another example, the reference chamber portion of the conduit gas system 6536 can be modeled as not thermally interacting with the boundaries of the reference chamber 6520, such that the temperature of the conduit gas system portion 6536 is a function of wall temperature and reference chamber 6520 pressure.

[0282] The formulas in this section use the following nomenclature: variable γ: specific heat ratio n: Polytropic coefficient p: pressure V: Volume T: Temperature Superscript: n: Polytropic coefficient nCC: Polytropic coefficient for control room nR: Polytropic coefficient for the reference chamber Subscript: c: Control room system CC: Physical control room f: value at the end of equalization i: the i-th value IC: Physical interconnection volume or manifold passage ICR: Physical interconnection volume on the reference chamber side of the valve IC_CC: Physical interconnection volume on the control chamber side of the valve l: Line or interconnect / manifold system 0: Starting value for equalization pmp: pump r:Reference system Ref:Physical reference chamber w: wall of interconnected volumes

[0283] The equation for the control chamber 6510 can be derived from the conceptual model of three separate mass systems in Figure 49A by understanding that the total volume of the control chamber mass 6510, reference chamber mass 6520, and interconnected volume mas...

Claims

1. 1. A method of priming a fluid line, comprising: attaching the fluid line to a receptacle of a fluid line condition detector; illuminating at least one LED of the fluid line condition detector a first plurality of times; monitoring an output signal of an optical sensor of the fluid line condition detector and determining a maximum light intensity value over the first plurality of times based on the output signal; determining a fill line threshold based on the maximum light intensity value; pumping a fluid into the fluid line; illuminating the at least one LED of the fluid line condition detector a second plurality of times; determining that the fluid line is filled when the optical sensor output signal indicates that the light intensity from the LED falls below the fill line threshold; A method comprising:

2. 2. The method of claim 1, further comprising comparing the maximum light intensity value with a limit value and overwriting the maximum light intensity value with the limit value if the maximum light intensity value does not meet the limit value.

3. 2. The method of claim 1, wherein determining the maximum light intensity value based on the output signal includes comparing the light intensity value indicated by the output signal during the first plurality of times with a calibration value to determine a ratio.

4. 4. The method of claim 3, wherein the calibration value is a light intensity value of the at least one LED output from the light sensor when no tube is installed in the receptacle.

5. The method of claim 1 , wherein determining the fill line threshold value comprises adding a constant to the percentage of the maximum light intensity value.

6. 2. The method of claim 1, wherein the second plurality of times occurs during the process of pumping the fluid into the fluid line.

7. 10. The method of claim 1, wherein the second plurality of illuminations from at least one LED includes illuminations from first, second, and third LEDs.

8. 10. The method of claim 1, further comprising stopping pumping the fluid upon determining that the fluid line is full.

9. 10. The method of claim 1, further comprising monitoring a volume of fluid pumped through the fluid line and pausing pumping when the volume of the pumped fluid exceeds a first volume threshold.

10. 10. The method of claim 9, further comprising resuming the pumping in response to receiving a user input indicating that the fluid line is not yet completely filled.

11. 10. The method of claim 9, further comprising inhibiting resumption of the pumping when the volume of the pumped fluid exceeds a second volume threshold.

12. 1. A method of priming a fluid line, comprising: placing the fluid line in a detector; illuminating the detector with light from at least one light source a first plurality of times while the fluid line is dry and within the detector; determining a maximum light intensity value over the first plurality of times based on an output signal from a sensor of the detector; determining a fill line threshold based at least in part on the maximum light intensity value; pumping a fluid into the fluid line; irradiating the at least one light source with a second plurality of light beams; ceasing the pumping when the output signal falls below the fill line threshold; A method comprising:

13. 1. A method of priming a fluid line, comprising: attaching the fluid line to a fluid line condition detector; illuminating the fluid line from at least one light source of the fluid line condition detector a first plurality of times while the fluid line is dry and within the fluid line condition detector; monitoring an output signal of the light sensor and determining a dry tube light intensity value for the first plurality of times based on the output signal; determining a fill line threshold based on the dry tube light intensity value; pumping a fluid into the fluid line; illuminating the fluid line condition detector a second plurality of times from the at least one light source; determining that the fluid line is filled when the optical sensor output signal falls below the fill line threshold; A method comprising:

14. 14. The method of claim 13, wherein determining the dry tube light intensity value includes comparing a maximum light intensity value from the light sensor over the first plurality of times with a limit value, and overwriting the maximum light intensity value with the limit value if the maximum light intensity value does not meet the limit value.

15. 14. The method of claim 13, wherein determining the dry tube light intensity value comprises comparing the light intensity value indicated by the output signal over the first plurality of times with a calibration value to determine a ratio, the calibration value being the light intensity value of the at least one light source output from the light sensor when no tube is attached to the fluid line condition detector.

16. 14. The method of claim 13, wherein illuminating a second plurality of times from the at least one light source of the fluid line condition detector includes illuminating light from first, second, and third LEDs.

17. 14. The method of claim 13, further comprising stopping pumping of the fluid upon determining that the fluid line is filled.

18. 14. The method of claim 13, further comprising monitoring a volume of fluid pumped through the fluid line and pausing pumping when the volume of the pumped fluid exceeds a first volume threshold.

19. 20. The method of claim 18, further comprising resuming the pumping in response to receiving a user input indicating that the fluid line is not yet completely filled.

20. 20. The method of claim 18, further comprising inhibiting resumption of the pumping when the volume of the pumped fluid exceeds a second volume threshold.

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