Systems and methods for incorporating patient pressure into medical fluid delivery

Abstract

A system and method for incorporating patient pressure into medical fluid delivery. A medical fluid delivery machine includes: a pump interface having an actuation region for delivering positive or negative pressure to a medical fluid handling device; a pressure sensor positioned to measure pressure within the actuation region; a valve positioned to selectively vent the actuation region to atmosphere; and a control unit in signal communication with the pressure sensor and in control communication with the valve, the control unit executing a sequential program during pumping in which: (i) application of positive or negative pressure to the actuation region is discontinued, the valve is switched to vent the actuation region to atmosphere, the valve is then switched to close the actuation region to atmosphere, and at least one pressure signal reading is obtained via the pressure sensor; and (ii) based on the at least one pressure signal reading, a determination is made as to whether application of positive or negative pressure to the chamber should be resumed.

Description

[0001] This application is a divisional application of the invention patent application with the application date of June 21, 2018, application number 201880040324.4 (international application number PCT / US2018 / 038755), and invention name “System and method for incorporating patient pressure into medical fluid delivery”. Technical Field

[0002] The present invention relates generally to medical fluid delivery machines and, more particularly, to patient pressure measurement in conjunction with medical fluid delivery. Background Art

[0003] One type of medical fluid delivery relevant to the present invention is that used to treat renal failure. A person's renal system can fail for a variety of reasons. Renal failure produces several physiological abnormalities. For example, the patient is no longer able to balance water and minerals or excrete the daily metabolic load. Toxic end products of nitrogen metabolism (urea, creatinine, uric acid, etc.) can accumulate in the blood and tissues.

[0004] Renal failure and reduced renal function have been treated by dialysis. Dialysis removes waste, toxins and excess water from the body, and kidneys that otherwise function normally will remove these waste, toxins and excess water. One type of dialysis treatment is peritoneal dialysis, which injects a dialysis solution (also referred to as dialysis fluid) into the patient's peritoneal cavity via a catheter. The dialysis fluid contacts the peritoneum of the peritoneal cavity. Due to diffusion and osmosis (i.e., producing an osmotic gradient across the entire membrane), waste, toxins and excess water enter the dialysis fluid from the patient's bloodstream through the peritoneum. The osmotic agent in dialysis provides an osmotic gradient. The used or consumed dialysis fluid is discharged from the patient, thereby removing waste, toxins and excess water from the patient. This cycle is, for example, repeated many times.

[0005] There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal dialysis, and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis treatment. Here, the patient manually connects an implanted catheter to a drain tube to allow used or consumed dialysis fluid to drain from the peritoneal cavity. The patient then connects the catheter to a fresh dialysis fluid bag to inject fresh dialysis fluid into the patient's body through the catheter. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to remain in the peritoneal cavity, where waste, toxins, and excess water are transferred. After the dwell period, the patient repeats the manual dialysis procedure (e.g., four times a day), with each treatment lasting about an hour. Manual peritoneal dialysis requires a significant amount of patient time and energy, leaving ample room for improvement.

[0006] Automated peritoneal dialysis ("APD") is similar to CAPD in that it also includes drain, fill, and dwell cycles. However, the APD machine typically performs these cycles automatically while the patient sleeps. The APD machine relieves the patient from having to manually perform treatment cycles or have supplies delivered during the day. The APD machine is fluidly connected to an implanted catheter, a source or bag of fresh dialysis fluid, and a fluid drain. The APD machine pumps fresh dialysis fluid from the dialysis fluid source through the catheter into the patient's peritoneal cavity. The APD machine also allows the dialysis fluid to remain in the cavity and transfer waste, toxins, and excess water. The fluid source can include multiple sterile dialysis fluid bags.

[0007] The APD machine pumps used or consumed dialysis fluid from the peritoneal cavity, through a catheter, to a drain. As with the manual process, several drain, fill, and dwell cycles occur during APD. The "last fill" occurs at the end of APD and remains in the patient's peritoneal cavity until the next treatment. Dialysis fluid is typically "circulated" (filled, dwelled, and drained) four to five times during a treatment (e.g., overnight treatment). Typical fill volumes vary depending on several clinical factors, but on average can be about 2.0 to 2.5 liters.

[0008] One problem with APD machines is that, while the machine records and therefore knows how much fluid has been delivered to and removed from the patient, it actually does not know how much dialysis fluid remains in the patient at the end of the drain. That is, the machine may believe it has completely emptied the patient, but a certain residual amount may still remain in the patient's peritoneal cavity. This phenomenon is primarily due to the fact that the amount of ultrafiltration ("UF") removed from the patient is variable in peritoneal dialysis, rather than a controlled amount as in hemodialysis or other renal therapies. With PD, the amount of UF removed depends on the osmotic capacity of the solution used, the length of time the solution remains within the patient's peritoneum, and the ability of the patient's peritoneal wall to transport UF to the peritoneum (where it can be removed from the patient). Therefore, it is left to the doctor or clinician to predict how much UF will be removed during the dwell period of a cycle. For example, the doctor or clinician may predict that the amount of UF generated during the dwell period will be 7% of the fill volume. However, the actual amount of UF may be greater or less than the precise 7% calculated, leading to uncertainty associated with patient drainage.

[0009] Another factor associated with uncertainty is exchanges, such as midday exchanges, which are performed manually without the use of an APD machine. The first step in a treatment involving an APD machine is typically a drain step to remove the spent peritoneal dialysis fluid that remains in the patient's body during the day. When a midday exchange is performed, the patient manually drains the spent fluid until the patient feels empty and then refills with fresh fluid. The drain and refill amounts are typically not recorded, and even if they are recorded, they are not entered into the APD machine. Due to the refill, there is also a UF amount, which, for the reasons discussed above, increases uncertainty. As a result, at the initial drain of the next nightly APD treatment, it is not known exactly how much daytime fluid must be drained. Furthermore, the uncertainty of the initial drain leads to even greater uncertainty regarding how much fluid will remain in the patient's body at the end of each cycle.

[0010] Uncertainty about drainage can lead to overfilling the patient at the next fill. Overfilling the patient can cause excessive pressure on the patient's diaphragm, blood vessels, and internal organs, causing patient discomfort and potentially adversely affecting cardiopulmonary function.

[0011] For the reasons stated above, there is a need for a better method to determine how much fluid is remaining in a patient to avoid overfilling and a need for a more accurate clinical understanding of how much spent dialysis fluid is remaining in a patient. Summary of the Invention

[0012] The present invention describes systems and methods for pumping medical fluids to a patient while preventing overfilling and overpressurizing the patient. The present invention is described using peritoneal dialysis ("PD") as an example therapy that can benefit from the systems and methods herein. However, it should be understood that the systems and methods herein can be applied to any type of medical fluid delivery in which a medical fluid is delivered to and collected in an area of ​​a patient's body where pressure may be generated. In addition to PD, the systems and methods herein can also be applied to medical fluid delivery for, for example, medication and / or nutritional fluids.

[0013] The systems and methods herein measure pressure within a patient's body as fluid is being delivered to or removed from the patient. While controlling positive pressure and preventing overfilling is a primary concern, it is also desirable to be able to monitor and control negative pressure applied to the patient (e.g., during fluid removal) because excessive negative pressure can also cause patient discomfort. In either case, it is envisioned that as the patient becomes full or empty, a spike in positive or negative pressure will occur. When this pressure spike is sensed, pumping is stopped to prevent over-pressurization (positive or negative) of the patient.

[0014] In one main embodiment, an APD machine uses positive pneumatic pressure to fill a patient. The APD includes a pump interface that may include a pump actuation area for receiving positive and negative air pressures, with positive pressure being used to fill the patient with fresh dialysis fluid and negative pressure being used to drain spent dialysis fluid from the patient. A medical fluid handling device (e.g., a disposable cassette) is pressed against the pump actuation area. In one embodiment, the disposable cassette includes a fluid chamber that mates with the pneumatic actuation area of ​​the pump interface. The chamber and the actuation area are separated by a flexible membrane provided by the disposable cassette. Negative pneumatic pressure is applied to the pneumatic actuation area to pull the flexible membrane toward the walls of the area, thereby drawing fluid into the fluid chamber. Positive pressure is applied to the actuation area to push the flexible membrane toward the walls of the fluid chamber, thereby pushing fluid from the fluid chamber toward the patient. The above process is repeated multiple times until the prescribed patient fill volume has been delivered to the patient.

[0015] The APD machine is controlled by a control unit. The control unit may include one or more processors, one or more memories, and one or more sub-controllers or delegate controllers. The control unit controls multiple valves of the APD machine, which are, for example, pneumatic valves and are used to (i) open and close the pneumatic chamber relative to the atmosphere to vent the chamber, (ii) open and close the positive pressure supply to the pneumatic chamber, (ii) open and close the negative pressure supply to the pneumatic chamber, (iii) open and close the fluid line to the fluid chamber of the cassette, and (iv) open and close the fluid line from the fluid chamber of the cassette to the patient. Some of these valves can be reused for a second pneumatic chamber of the pump interface and a matching second fluid chamber of the disposable cassette.

[0016] The control unit also receives pressure signal readings from a plurality of pressure sensors of the APD machine, such as pneumatic pressure sensors, which are positioned and configured to read the pressure inside each pneumatic actuation region of the pump interface of the APD machine. These pressure sensors can, for example, be configured to read a range of 18 centimeters of water ("cm") to 24 centimeters of water. Because the flexible membrane between the pneumatic actuation region and the fluid chamber is relatively thin, the pressure measured in the pneumatic actuation region can be considered equal to the fluid pressure in the fluid chamber of the cartridge and in the fluid lines (e.g., the rigid cartridge passages and the flexible tubing attached to the cartridge) that are in fluid communication with the fluid chamber of the disposable cartridge.

[0017] In one embodiment, the control unit is programmed to periodically: stop the pump stroke by closing the valve between the positive pressure source and the pneumatic chamber, and vent the pneumatic chamber to atmosphere by opening a valve in the exhaust line leading from the pneumatic chamber. When the pneumatic chamber is completely emptied, the control unit closes the exhaust valve, so that the pneumatic chamber is now completely closed. The pneumatic chamber is then pressurized by the fluid in the fluid chamber of the disposable cassette, the line leading from the disposable cassette to the patient, and the fluid in the patient's peritoneal cavity. When the pressure generated across the cassette, the fluid line, and the peritoneal cavity stabilizes, it represents the current patient pressure. The control unit then takes one or more pressure readings (e.g., multiple readings and averages them).

[0018] The present invention contemplates doing different things with the pressure readings. In one embodiment, the control unit compares the pressure reading with one or more pressure readings from one or more previous sequences. The control unit looks for a pressure peak or a change in the slope of the curve connecting the pressure readings to indicate that the peritoneal cavity is full. If no peak is sensed, pumping is resumed. If a peak is sensed, the remainder of the filling is stopped. This embodiment is advantageous because the pressure comparison is to the pressure change rather than comparing the pressure reading to a pressure limit, which may vary from patient to patient, from treatment to treatment for a given patient, or even change during treatment due to changes in the patient's pressure head height. In an alternative embodiment, the comparison of the slope of the pressure curve can be combined with an upper pressure limit, for example setting the upper pressure limit to be high enough for all patients in all treatments.

[0019] Pressure spikes may occur for reasons other than patient refilling. For example, a patient (perhaps sleeping) may inadvertently kink the tubing, causing a pressure spike. Alternatively, the patient's catheter may become temporarily partially blocked, also causing a pressure spike. Alternatively, the patient may change the head height relative to the medical fluid delivery machine or couch during the measurement period. Even if a pressure spike is sensed, to avoid stopping refilling before the patient is fully refilled, it is contemplated that the control unit could be programmed to reverse the pump to withdraw a known amount of dialysis fluid from the patient (e.g., one or more pump strokes of fluid), and then reverse the pump again to pump the same one or more pump strokes of fluid back into the patient, during which the pressure measurement sequence is repeated. Alternatively, pressure measurements could be monitored during both fluid removal and refilling to confirm that pressure spikes disappear and then reappear. If pressure measurements again indicate that the patient is fully refilled (e.g., via pressure peak or slope change techniques), the remaining refill is stopped. However, if pressure measurements do not indicate that the patient is fully refilled, patient refilling can continue, knowing that the pressure measurement sequence will be repeated soon.

[0020] In one embodiment, the control unit repeats the pressure measurement sequence periodically during patient fill (or drain), for example, once every 100 milliliters to 150 milliliters ("mL") of dialysis fluid fill, where a full pump stroke may be approximately 20 mL. The pressure measurement sequence may take about 3 seconds to about 30 seconds, for example, to completely empty the dialysis chamber and then re-pressurize to patient pressure (e.g., intraperitoneal pressure ("IPP")), at which time one or more pressure readings are recorded. In one embodiment, the pressure measurement sequence is preferably performed mid-stroke rather than at the end of a stroke where there is a slight pause, because the flexible membrane of the disposable cassette should be allowed to flex due to the patient pressure, thereby producing an accurate patient pressure reading in the pneumatic chamber, rather than sticking to the walls of the fluid chamber or pneumatic actuation area at the end of the stroke.

[0021] Alternatively, the control unit may compare the pressure reading to a pressure limit and resume pumping if the measured pressure reading is within the pressure limit. If the measured pressure reading is outside the pressure limit, the control unit may stop filling the remaining portion. The pressure limit may be set based on a determined pressure head height of the patient relative to the machine.

[0022] In yet another alternative embodiment, the control unit compares the pressure reading to the pressure limits and resumes pumping if the measured pressure reading is within the pressure limits, and additionally executes the above sequence one or more times if the measured pressure reading is outside the pressure limits. If the pressure reading remains outside the pressure limits for multiple sequences, the control unit stops filling the remaining portion.

[0023] The systems and methods of the present invention are not limited to pneumatic pumping or the use of disposable cassettes. In another primary embodiment, an external pressure sensor device is employed at a designated portion of a medical fluid handling device, which can be a pump tubing set or a disposable cassette and associated fluid lines. Alternatively, the external pressure sensor device is associated with a PD patient's transfer kit, which serves as the interface between the patient line of the fluid handling device and the patient's indwelling PD catheter. Because the external pressure sensor device is not integrated into the medical fluid delivery machine itself, the external pressure sensor device is considered external. The pressure sensor device is alternatively located internally on: (i) the patient line, such as at the distal end of the patient line; (ii) the disposable cassette, such as in a fluid pathway of the disposable cassette that leads from the pump chamber to the patient port of the disposable cassette or the patient port itself; or (iii) the patient's transfer kit. In each of (i) to (iii), the sensor is positioned so as to contact the fluid. The sensor device can be powered by a small battery provided with the pressure sensor, or have power leads that extend externally to the fluid handling device for receiving external power, such as from a medical fluid delivery machine.

[0024] The pressure sensor can be a micro-machined ("MEMS") type sensor, such as those found in mobile phones and wearable devices for altitude sensing. The sensor device can be configured to wirelessly communicate with the medical fluid delivery machine. The medical fluid delivery machine can be configured so that upon detecting the presence of a fluid handling device, the medical fluid delivery machine automatically searches for a wireless signal. When the medical fluid delivery machine detects the signal, the medical fluid delivery machine can begin acquiring readings.

[0025] In one embodiment, the medical fluid delivery machine waits for a pause in pumping to obtain a reading, which is considered a reading of the patient pressure. In another embodiment, the medical fluid delivery machine reads the pressure sensor continuously or at regular intervals (these regular intervals are not synchronized with the pumping cycle). Here, the medical fluid delivery machine can be programmed to perform signal analysis, such as a fast Fourier transform ("FFT"), on the readings to attempt to decouple resonant frequency components and evaluate whether any components may be indicative of or may be correlated with patient pressure.

[0026] Regardless of how the external pressure sensor patient pressure readings are obtained, they can be analyzed as discussed above for the primary embodiment of pneumatic pumping, for example, compared to limits or compared to themselves for curve slope or pressure peak analysis.

[0027] For either of the main embodiments, it is contemplated that a patient pressure analysis may be performed at the start of treatment. As discussed above, with an APD, it is difficult to know how much fluid is remaining in the patient at the start of the first patient fill. However, once the first full fill has been established via the structures and methods discussed herein, a better understanding of the patient's condition can be obtained. A fill / drain protocol can be developed based on the sensed full fill and continued without having to perform a patient pressure analysis again. It may be desirable to have the planned continued fill be slightly less than the full fill determined based on pressure sensing to allow for increased volume during the dwell period due to UF (ultrafiltration). In one embodiment, the clinician or physician may set an upper limit for the planned fill that cannot be exceeded regardless of what the sensed full fill indicates.

[0028] For either of the primary embodiments, it is contemplated that patient pressure analysis may be performed alternately with each fill and / or drain. As discussed above, patients do not always empty completely. If the initial drain prior to the initial fill is incomplete, the sensed full fill volume may be less than if the patient had completely emptied. Therefore, it is contemplated that the next fill volume may be planned based on the previously sensed full fill volume, taking into account the UF that may accumulate during the indwelling period. Furthermore, in one embodiment, the clinician or doctor may set an upper limit for the planned fill volume, which cannot be exceeded regardless of the sensed full fill volume.

[0029] In view of the disclosure herein and without limiting the invention in any way, unless otherwise stated, in a first aspect of the invention which may be combined with any other aspect listed herein, a medical fluid delivery machine operates a medical fluid treatment device, the medical fluid delivery machine comprising: a pump interface, the pump interface including an actuation area, the actuation area being used to deliver positive pressure or negative pressure to the medical fluid treatment device, respectively, to move medical fluid into or out of the device, the medical fluid treatment device being capable of being placed in fluid communication with a patient; a pressure sensor, the pressure sensor being positioned and configured to measure the pressure caused by a pressure within the actuation area; a valve positioned and configured to selectively vent the actuation area to atmosphere; and a control unit in signal communication with the pressure sensor and in control communication with the valve, the control unit being programmed to execute a sequential procedure during pumping, wherein: (i) application of positive or negative pressure to the actuation area is discontinued, the valve is switched to vent the actuation area to atmosphere, and then the valve is switched to close the actuation area relative to atmosphere, and at least one pressure signal reading is obtained via the pressure sensor, and (ii) a determination is made whether application of positive or negative pressure to the actuation area should be resumed based on the at least one pressure signal reading.

[0030] In a second aspect of the invention, which may be combined with any other aspect enumerated herein unless otherwise stated, the control unit comprises at least one of: (i) at least one processor, (ii) at least one memory, or (iii) at least one delegate controller.

[0031] Unless otherwise stated, in a third aspect of the invention, which may be combined with any other aspect enumerated herein, the valve is a first valve and includes a second valve controlled by a control unit that is also programmed so that (i) stopping applying positive or negative pressure to the actuating area includes switching the second valve to close the actuating area from the positive pressure source or the negative pressure source, and (ii) resuming applying positive or negative pressure to the chamber includes switching the second valve to open the actuating area to the positive pressure source or the negative pressure source.

[0032] In a fourth aspect of the invention, which may be combined with the third aspect in conjunction with any other aspect listed herein unless otherwise stated, the pressure sensor is placed in fluid communication with a line leading from a positive or negative pressure source to the actuation area.

[0033] In a fifth aspect of the present invention, which may be combined with any other aspect listed herein unless otherwise stated, the pumping process comprises a pump stroke process having a pump stroke start and a pump stroke end.

[0034] Unless otherwise stated, in a sixth aspect of the invention which may be combined with any other aspect enumerated herein, the actuation area is a first actuation area, and wherein the pump interface includes a second actuation area for delivering positive or negative pressure to the medical fluid handling device to move medical fluid into or out of the device, and wherein the control unit is programmed to perform (i) and (ii) for both the first actuation area and the second actuation area.

[0035] Unless otherwise stated, in a seventh aspect of the invention which may be combined with any other aspect enumerated herein, determining whether positive or negative pressure should be resumed to the actuation area comprises programming the control unit to (iii) determine a difference between the at least one pressure signal and at least one pressure signal from at least one previous sequential program.

[0036] In an eighth aspect of the invention, which may be combined with the seventh aspect in combination with any other aspect enumerated herein unless otherwise stated, the control unit is programmed to (iv) resume applying pressure if the pressure difference is at least substantially the same as the previously determined difference.

[0037] In a ninth aspect of the invention, which may be combined with the seventh aspect in combination with any other aspect listed herein unless otherwise stated, the control unit is programmed to (iv) not resume applying pressure if the pressure difference differs from a previously determined difference.

[0038] Unless otherwise stated, in the tenth aspect of the present invention, which may be combined with the ninth aspect in combination with any other aspect listed herein, the difference between the pressure differences is required to be at least a certain amount so as not to restore the applied pressure.

[0039] Unless otherwise stated, in an eleventh aspect of the invention, which may be combined with the seventh aspect in combination with any other aspect enumerated herein, the control unit is programmed (iv) such that if the difference is different from the previously determined difference, at least one additional sequential procedure is executed, and if the new difference is still different from the previously determined difference, the application of pressure is not resumed.

[0040] Unless otherwise stated, in a twelfth aspect of the present invention which may be combined with the seventh aspect in combination with any other aspect listed herein, the control unit is programmed to: (iv) cause reverse pumping of the medical fluid volume if the difference value is different from the previously determined difference value, and then reverse pumping of the medical fluid volume again, and (v) perform (i) to (iii) again.

[0041] Unless otherwise stated, in a thirteenth aspect of the invention, which may be combined with the twelfth aspect in combination with any other aspect enumerated herein, the control unit is programmed not to resume applying pressure if the difference in (iii) being performed again is still different from the previously determined difference.

[0042] Unless otherwise stated, in a fourteenth aspect of the invention, which may be combined with the twelfth aspect in combination with any other aspect enumerated herein, the control unit is programmed to resume applying pressure if the difference in (iii) being performed again is at least substantially the same as the difference previously determined.

[0043] Unless otherwise stated, in a fifteenth aspect of the present invention, which can be combined with the twelfth aspect in combination with any other aspect enumerated herein, a sequential procedure is provided for patient priming, in which a positive pressure is applied in an actuation area, wherein reverse pumping removes a volume of medical fluid from the patient and reverse pumping again returns the volume of medical fluid to the patient, and wherein, after the actuation area is vented to atmosphere and then closed relative to atmosphere, the pressure within the actuation area is considered to be the pressure within the patient.

[0044] Unless otherwise stated, in a sixteenth aspect of the present invention, which may be combined with the seventh aspect in combination with any other aspect enumerated herein, the control unit is programmed to: apply a smoothing filter to the determination of multiple pressure differences in looking for changes in the pressure difference indicating that the applied pressure should not be restored.

[0045] Unless otherwise stated, in a seventeenth aspect of the present invention which may be combined with any other aspect enumerated herein, determining whether positive or negative pressure should be resumed to the actuation area includes determining whether the at least one pressure signal reading is within a pressure limit.

[0046] In an eighteenth aspect of the present invention, which may be combined with the seventeenth aspect in conjunction with any other aspect listed herein, unless otherwise stated, the control unit is programmed not to resume applying pressure if the at least one pressure signal reading is outside the pressure limits.

[0047] In a nineteenth aspect of the invention, which may be combined with any other aspect listed herein unless otherwise stated, the duration for completing (i) is from about 3 seconds to about 30 seconds.

[0048] In a twentieth aspect of the invention, which may be combined with any other aspect listed herein, unless otherwise stated, the sequential procedure is repeated during pumping of incremental volumes of the medical fluid.

[0049] In the twenty-first aspect of the present invention, unless otherwise specified, the combination Figures 1 to 7 Any structure, functionality, and alternatives discussed may be combined with any other aspect listed herein.

[0050] Unless otherwise stated, in a twenty-second aspect of the present invention, which may be combined with any other aspect enumerated herein, a medical fluid delivery system comprises: a medical fluid handling device comprising a patient line for being placed in communication with a patient fluid; and a medical fluid delivery machine comprising: a pump actuator for actuating the medical fluid handling device to move medical fluid into or out of the device; a pressure sensor positioned and disposed within the medical fluid handling device so as to be able to sense the pressure of the medical fluid; and a control unit in signal communication with the pressure sensor and in control communication with the pump actuator, the control unit being programmed to, during pumping: (i) determine whether at least one signal reading from the pressure sensor or a component of the at least one signal reading indicates pressure within the patient's body, and (ii) determine whether to continue pumping or stop pumping from the at least one pressure signal reading or component reading indicating pressure within the patient's body.

[0051] Unless otherwise stated, in a twenty-third aspect of the present invention, which can be combined with the twenty-second aspect in combination with any other aspect listed herein, the medical fluid handling device also includes a patient transfer kit for connecting to the patient's indwelling catheter, and wherein the pressure sensor is placed within the patient transfer kit.

[0052] In a twenty-fourth aspect of the present invention, which may be combined with the twenty-second aspect in combination with any other aspect listed herein unless otherwise stated, the medical fluid processing device further comprises a pumping cassette, and wherein the pressure sensor is positioned within the pumping cassette.

[0053] In a twenty-fifth aspect of the invention, which may be combined with the twenty-second aspect in combination with any other aspect listed herein unless otherwise stated, the pressure sensor is placed in the patient line.

[0054] In a twenty-sixth aspect of the invention, which may be combined with the twenty-second aspect in combination with any other aspect listed herein unless otherwise stated, the pressure sensor is a micromechanical ("MEMS") sensor.

[0055] In a twenty-seventh aspect of the invention, which may be combined with the twenty-second aspect in combination with any other aspect listed herein unless otherwise stated, the control unit is programmed to perform at least (i) or (ii) in the frequency domain.

[0056] Unless otherwise stated, in aspect 28 of the present invention, which may be combined with aspect 22 in combination with any other aspect listed herein, determining whether to continue pumping or stop pumping from the at least one pressure signal reading or the component of the at least one pressure reading includes evaluating changes in the at least one pressure signal reading or the component of the at least one pressure reading.

[0057] In the twenty-ninth aspect of the present invention, unless otherwise specified, in combination Figures 1 to 7 Any structure, functionality, and alternatives discussed in any of the figures may be combined with Figures 1 to 7 Any structure, functionality, and alternative combinations discussed in any other figure may be combined.

[0058] In view of the above discussion and various aspects of the present invention, it is therefore an advantage of the present invention to provide improved medical fluid delivery to a patient.

[0059] Another advantage of the present invention is that it provides improved automated peritoneal dialysis ("APD") treatment.

[0060] Yet another advantage of the present invention is improved patient comfort.

[0061] Yet another advantage of the present invention is that it attempts to maximize fluid delivery capacity while preventing overfilling of the patient.

[0062] The advantages discussed herein may be found in one or some (but not all) of the embodiments disclosed herein.Additional features and advantages are described herein and will be apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 is a process flow diagram illustrating various embodiments of the patient pressure pumping method of the present invention.

[0064] Figure 2 This diagram is used to obtain Figure 1 A process flow chart of one embodiment of a method for using patient pressure readings.

[0065] Figure 3 This diagram is used to obtain Figure 1

[0014] Figure 1 is a process flow chart of another embodiment of a method for using patient pressure readings.

[0066] Figure 4is a graph illustrating how patient pressure varies relative to the degree to which a cavity within the patient's body fills with medical fluid.

[0067] Figure 5 is a graph illustrating the output of one embodiment of the pressure validation routine of the present invention.

[0068] Figure 6 is a schematic diagram illustrating one example apparatus for implementing the patient pressure pumping method of the present invention.

[0069] Figure 7 is a schematic diagram illustrating another example apparatus for implementing the patient pressure pumping method of the present invention. DETAILED DESCRIPTION

[0070] Referring now to the drawings and in particular to Figure 1 , various embodiments of the patient pressure pumping method for the present invention are illustrated by method 10. At oval box 12, method 10 begins. At box 14, method 10 performs a portion of a fill procedure or a drain procedure. In one embodiment, the fill procedure or the drain procedure is a peritoneal dialysis ("PD") procedure that is performed as part of a PD cycle, wherein there may be multiple fill, dwell, and drain cycles during the course of a PD treatment. However, it should be understood that the fill procedure or the drain procedure of box 14 can be applied to any type of medical fluid delivery, wherein a medical fluid is delivered to (and possibly removed from) a certain area of ​​a patient's body and collected in that area where pressure may be generated. In addition to PD, the systems and methods herein can also be applied to medical or nutritional fluid delivery.

[0071] Block 16 and diamond 18 form a sequential process in which a determination is made as to whether the patient is completely filled during a fill procedure or completely emptied during a drain procedure. At block 16, method 10 obtains at least one pressure reading indicating the pressure of the medical fluid remaining in the patient. If the medical fluid delivery is a PD delivery, the pressure in the patient is the patient's peritoneal cavity or intra-abdominal pressure ("IPP"). However, as described above, the patient's pressure may be at any other location in the patient's body, such as the patient's stomach or other cavity.

[0072] There are two main embodiments for obtaining the at least one pressure reading at box 16 . Figure 2 A primary pressure reading embodiment is shown in which pumping is paused to allow the pumping pressure to subside so that the pressure measured is the patient's pressure rather than the pump's pressure. Depending on the type of medical fluid delivery pump used as described below, Figure 2 The approach can take different forms. Figure 3Another primary pressure reading embodiment is shown, in which pressure readings are taken continuously or semi-continuously (e.g., in processor clock cycles) during pumping. Thus, these readings show pressure waves that represent the pressure due to the pump. However, signal processing can be performed that looks for a component of a separate signal or a total signal that represents or can be correlated with patient pressure (e.g., IPP). This signal or component signals are then used for analysis at diamond 18.

[0073] At diamond 18, a determination is made as to whether the pressure readings indicate that the patient is full (for a patient fill), or empty (for a patient drain). There are many different embodiments for performing the analysis of diamond 18. In one embodiment, the one or more pressure readings are compared to one or more previous readings to look for a pressure difference or slope of the pressure curve that indicates a pressure spike is starting or ongoing. As described below in conjunction with Figure 4 As illustrated, as a PD patient begins to fill up, the peritoneal cavity tends to resist the introduction of more dialysis fluid, causing the intracavitary pressure to rise faster than previously (where the previous pressure increase was due to an increase in the head height of the medical fluid accumulating in the peritoneal cavity). In this embodiment, the pressure differential is assessed to determine whether the patient is full (or nearly full). Because determining precise pressure limits for multiple patients can be difficult, and furthermore, determining precise pressure limits across multiple treatments for a single patient can also be difficult, it can be advantageous to view the pressure differential (rather than comparing pressure readings to pressure limits). Patient pressures within the same treatment can vary, for example, due to variations in the relative head height between the patient and the machine.

[0074] The assessment can be performed in a variety of ways. In one embodiment, a current pressure reading (or a current average of multiple pressure readings) is compared to a previous pressure reading (or a previous average of multiple pressure readings) to produce a current pressure differential, and the current pressure differential is compared to a pressure differential limit. In another embodiment, the current pressure differential is averaged with at least one previous pressure differential and compared to a pressure differential limit. In yet another alternative embodiment, the current pressure differential is compared to one or more previous pressure differentials to determine whether a change in slope indicates that the patient is full. For example, the control unit of the machine can look for a new slope that is at least twice the old slope to determine whether the patient is full.

[0075] An algorithm programmed into the control unit of the medical fluid delivery machine may employ a smoothing filter to smooth patient pressure (e.g., IPP) data relative to patient medical fluid volume data to help detect points where the slope increases significantly (e.g., increases by a factor of two or greater). The smoothing algorithm may involve the use of an approximating function that captures patterns in the data while filtering out noise.

[0076] Regardless of which embodiment of the pressure differential or pressure peak embodiment is used for the determination at diamond 18, if the determination passes any criteria used, then the patient is determined to be not full (or nearly full) and the method 10 returns to diamond 14 to continue filling the patient. The cycle between filling the patient at diamond 14, taking the pressure reading at diamond 16, and determining whether the patient is full (or nearly full) or not full at diamond 18 is repeated until the pressure differential determination fails to meet the criteria, at which point the method 10 continues to determine whether a verification determination exists at diamond 20.

[0077] In another embodiment of the determination at diamond 18, the one or more pressure readings are compared to a pressure limit, wherein the pressure limit indicates that the patient is full or nearly full. During a patient fill procedure, for example, at a specific relative head height relative to a medical fluid delivery machine, the pressure reading can be compared to a pressure limit (e.g., a standard pressure limit or a pressure limit determined for a specific patient or a specific type of patient (e.g., height, weight, mode of delivery, and / or gender)). If the pressure reading at diamond 18 is equal to or below the limit, it is determined that the patient is not full (or nearly full), and method 10 returns to diamond 14 to continue patient filling. The cycle between patient filling at diamond 14, pressure reading at diamond 16, and determination of whether the patient is full (or nearly full) or not full at diamond 18 is repeated until the pressure reading reaches or exceeds the pressure limit, at which point method 10 continues to determine whether a verification determination exists at diamond 20.

[0078] In yet another alternative embodiment for the determination at diamond 18, a combination of the first and second embodiments may be employed. For example, any pressure differential implementation may be combined with pressure limits that can be determined based on the pressure differential analysis unless one or more of the currently measured readings are outside of the limits, in which case the patient is determined to be full (or nearly full). For example, a physician or clinician may specify a maximum safe pressure for the patient that will not be exceeded regardless of the pressure differential information provided. In this alternative embodiment, the cycle between patient filling at block 14, pressure readings at block 16, and determinations of whether the patient is full (or nearly full) or not full at diamond 18 is repeated again until the pressure differential determination fails to meet the criteria or reaches or exceeds a pressure limit, at which point method 10 continues to determine whether a verification determination has occurred at diamond 20.

[0079] The verification determination at diamond 20 is meant to indicate, in one embodiment, that there may not be any verification at all, and that the confirmation at diamond 18 is sufficient to fully determine whether the patient is full (or nearly full) of medical fluid. The verification determination at diamond 20 is meant to indicate, in another embodiment, that verification is situational and may not always be performed. Verification, when performed, can be performed in different ways. For example, if the pressure reading at diamond 18 is compared to a pressure limit, the verification at box 22 may involve taking one or more additional pressure readings to determine whether the reading is consistently (e.g., on average) at or above the pressure limit. The additional one or more pressure readings at verification determination 20 may or may not involve first pumping a small amount of additional therapeutic fluid to the patient.

[0080] Alternatively, a certain amount of fluid may first be removed from the patient, followed by a pressure measurement, after which the same amount is pumped back into the patient, and a second pressure measurement and assessment performed according to one of the embodiments for diamond 18 . Figure 5 The diagram shows an example result of this procedure. By subtracting and then adding back a certain amount of fluid (e.g., approximately 112 ml), the machine's control unit can determine whether the pressure spike or limit breach is due to the patient filling up (seeing the peak again) or due to other factors (e.g., head height change, coughing, or line blockage), in which case the peak is no longer seen. The fluid removal, pressure reading, fluid addition, pressure reading, and subsequent evaluation of diamond 18 can be repeated one or more times to reach a final conclusion.

[0081] As indicated at diamond 24, for any of the above verification embodiments, if the verification result does not correspond to the patient being full (or nearly full), the method 10 returns to filling or draining at box 14, starting the entire process just described again. The inconsistent result at diamond 24 may be due to system noise factors, such as patient movement, coughing, or changing indenter height (for example, the effect of patient indenter height variation, see Figure 5 Alternatively, (i) if the verification result is consistent with the patient being full (or nearly full), or (ii) there is no verification, such as determined at diamond 20, the method 10 performs a post-patient fill (or drain) procedure, such as indicated by block 26.

[0082] The verification routine taught in conjunction with block 22 may be executed based on the discovery that the determination of patient full (or nearly full) at diamond 18 occurred at an unexpectedly low fill level. As previously discussed, medical fluid delivery machines, such as APD machines, know how much medical fluid has been delivered to a patient, but due to uncertainty regarding the residual patient volume prior to a patient fill, do not know how much fluid actually remains in the patient. Therefore, an unexpectedly low fill level may indicate that the patient had a large residual volume prior to a fill, and that the determination of patient full (or nearly full) was correct. However, the associated unexpectedly low fill level increases the likelihood of system noise that could cause the patient full (or nearly full) determination. The selected verification routine of block 22 is then executed. However, if the determination of patient full (or nearly full) at diamond 18 is accompanied by a fill level consistent with a patient full, the verification routine is not executed.

[0083] At box 26, method 10 has determined that the patient is fully filled (or nearly full). At box 26, method 10 executes a corresponding procedure, which can be one of a number of embodiments. In one embodiment, if the fill amount delivered at the patient pressure that leads to the conclusion that the patient is full (or nearly full) matches the expected full fill amount, the determined fill amount (e.g., for an APD) is set as the prescribed fill amount for a subsequent cycle. Here, in one embodiment, no patient pressure measurement is taken in the subsequent cycle. Alternatively, although the fill amount is set in the subsequent cycle, the patient pressure is still obtained at or near the time when the prescribed fill amount is reached in the patient (e.g., based on Figure 2 or Figure 3 ) to understand the consistency of the patient's pressure measurement chart when filled (or nearly filled) with the prescribed filling amount. This consistency can be accumulated in patient-specific files, which is useful for subsequent evaluation.

[0084] If the fill volume delivered at the verified patient pressure that resulted in the conclusion that the patient was full (or nearly full) does not match the expected full fill volume (e.g., the patient had a large residual volume prior to the fill), the fill volume determined in method 10 (e.g., for APD) is not set as the prescribed fill volume for the subsequent cycle. Instead, method 10 is repeated in the next cycle, and if necessary, in additional cycles until the verification determination at diamond 24 just described, until the fill volume corresponding to the patient pressure that resulted in the conclusion that the patient was full (or nearly full) matches the expected full fill volume, at which point the fill volume is set as the prescribed fill volume for the remainder of the cycle.

[0085] In an alternative embodiment to block 26 of method 10, method 10 is repeated for each subsequent cycle of treatment until the verification determination at diamond block 24, just described. For each cycle, the delivered fill volume and the verified patient pressure that concluded the patient was full (or nearly full) are recorded in a patient-specific file that is useful for subsequent evaluation. For each embodiment described for block 26, it is contemplated in one embodiment that the fill volume is not allowed to exceed the fill volume limit specified by the physician or clinician, even if the patient pressure measurement indicates that the patient is not full. However, it is contemplated that the patient pressure is recorded when the fill volume limit is reached, so that if the patient pressure continues to indicate that the patient is capable of receiving a larger fill volume, the patient's machine operation plan can be modified accordingly.

[0086] At oval 28, method 10 ends. Method 10 has been described primarily in conjunction with patient filling. As illustrated at box 14, and as briefly mentioned above, method 10 is not limited to a patient filling procedure and additionally includes a patient draining procedure. The patient draining procedure involves applying negative pressure to the patient. It should also be understood that the above-described method includes alternative embodiments at virtually every step, and in some cases, includes alternative implementations of the same embodiment. It is not necessary to enumerate every different combination of every possibility, and instead it should be appreciated that every possible combination of alternatives is contemplated unless expressly stated otherwise.

[0087] Now refer to Figure 2 , shown by method 40 in Figure 1Various embodiments of obtaining the one or more pressure readings at block 16 of method 10 of the present invention are described. At oval block 42, method 40 begins. At block 44, a medical fluid pump pumps a quantity of medical fluid into or out of a patient. At block 46, pumping is stopped for a period of time to allow the fluid pressures (i) in the pump, (ii) in the tubing leading from the pump to the patient, and (iii) within the patient to reflect not the pumping pressure but instead the fluid pressure within the patient, which is the head pressure of the fluid in the patient until the patient is full. At block 48, one or more pressure readings of the medical fluid are obtained, each representing the current patient fluid pressure, i.e., the IPP for PD. If multiple pressure readings are obtained at block 48, these pressure readings can be averaged at block 48 to provide an average patient pressure for the current pressure reading phase at block 48, which is recorded by the control unit of the medical fluid delivery device pumping the medical fluid. Similarly, the recorded pressure can be positive for patient filling and negative for patient draining. At oval 50 , method 40 ends.

[0088] The amount of medical fluid pumped at box 44 is selected to balance the sensitivity of the overall system and method, and the desire not to interrupt filling or draining too frequently, thereby interfering with treatment. That is, it is desirable to have a smaller amount of medical fluid pumped at box 44 so that more data points are generated and the system can react more quickly to the patient becoming completely full (or nearly full) or completely empty (or nearly empty). On the other hand, it is desirable not to interrupt treatment too frequently, delaying the overall treatment time and / or affecting the dose rate. In the APD example (where a typical fill volume might be about 2000 ml to 2500 ml), a prudent amount of medical fluid pumped at box 44 before stopping pressure measurement at box 46 might be from about 45 ml to about 90 ml. If a volumetric pump or diaphragm pump is used, the full stroke capacity might be from about 16 ml to about 25 ml. In this example, and depending on the stroke volume and the amount pumped at box 44, a pressure reading may be taken at box 46 every two to five pumping strokes. In one example, the amount of time required to take an appropriate pressure measurement indicative of the pressure in the patient at box 46 is from about 3 seconds to about 30 seconds.

[0089] Now refer to Figure 3 , illustrated by method 60 in Figure 1 Various alternative embodiments of obtaining the one or more pressure readings at block 16 of method 10 may be described. Figure 2 Method 40 with Figure 3The primary difference between method 40 and method 60 is that method 40 stops pumping and waits for the pressure measurement to reflect the patient's pressure, whereas method 60 takes pressure measurements during pumping and attempts to extract the component of the pressure reading that is indicative of the patient's pressure from the rest of the patient reading.

[0090] At oval 62, method 60 begins. At block 64, method 60 causes a pressure sensor to obtain continuous or semi-continuous (e.g., once per treatment cycle) readings during a patient pump priming or pump draining operation. The pressure sensor can be mounted in any area of ​​a fluid handling device (e.g., a disposable cartridge or associated fluid lines for PD, an infusion pump kit for medical or nutritional fluid delivery, etc.) that comes into contact with the medical fluid being delivered or removed. Pumping can be performed via a volumetric or diaphragm pump, a peristaltic pump, or a syringe pump.

[0091] At block 66, method 60 performs signal analysis on the received pressure signal. The signal analysis may involve, for example, a Fast Fourier Transform ("FFT"), which converts a time-dependent signal into the frequency domain (and vice versa), where different frequencies can be analyzed separately. Suitable FFT algorithms for performing the FFT include, but are not limited to, the Cooley–Tukey algorithm, the Bluestein FFT algorithm, the Bruun FFT algorithm, the Hexagonal Fast Fourier Transform, the Prime FFT algorithm, and the Rader FFT algorithm.

[0092] At box 68, method 60 examines the processed pressure signal or components of the processed pressure signal that represent or may be associated with the patient's internal pressure (e.g., IPP for PD). For example, experiments may indicate that a particular frequency of the FFT represents or may be associated with the patient's internal pressure. The control unit of the medical fluid delivery machine is programmed to analyze the particular frequency when obtaining the pressure reading. The analysis may include any type of frequency filtering (including but not limited to using a low-pass filter, a high-pass filter, a twin-T active notch filter, a band-pass filter, and combinations thereof) and any suitable and desired frequency amplification. The control unit may also convert the analyzed frequency into a numerical value representing the patient's internal pressure. The numerical value is then analyzed according to any of the embodiments discussed above in conjunction with the fill or empty diamond box 18 of method 10. At oval box 70, method 60 ends.

[0093] Now refer to Figure 4Graph 80 shows how patient pressure changes relative to the degree to which the patient's body cavity is filled with medical fluid. Graph 80 particularly illustrates the filling of the patient's peritoneal cavity. Graph 80 shows on the vertical axis IPP measured in centimeters of water ("cm") versus milliliters per square meter ("mL / m2"). 2 As shown in the figure, assuming a constant filling rate, the IPP increases linearly due to the increase in the pressure head height of the fluid in the patient's peritoneum. At approximately 1200 cubic millimeters (mm 3 At a fluid volume of 100 μg / cm2, the patient's peritoneum begins to fill up, and the pressure change increases for the same fluid volume increment. The slope can increase by a factor of two or more. This increase is caused by the fluid pushing against the peritoneal wall and the corresponding reaction force of the peritoneal wall against the fluid.

[0094] Thus, in one embodiment, it is contemplated to look for (and possibly verify) a change in slope to determine that the patient is full (or nearly full) and take appropriate action, e.g., stopping peritoneal filling and starting the indwelling portion of the cycle. Figure 4 Filling is stopped within the 200 mm 3 fill amount window shown in graph 80 between 1200 mm 3 and 1400 mm 3 .

[0095] Now refer to Figure 5 , illustrates a graph 90 showing the output of an example validation routine. Graph 90 shows on the vertical axis the IPP measured in kilopascals (kPa) versus the volume of fluid in the patient's peritoneal cavity measured in milliliters. Graph 90 is actually four graphs 92, 94, 96, and 98. Graphs 92 and 94 show step changes in slope at approximately 2000 milliliters of dialysis fluid volume in the patient's peritoneum. These step changes may be due to the patient's peritoneal cavity filling up, or due to external noise factors, such as patient movement, coughing, or changes in the patient's head height relative to the machine.

[0096] Thus, a verification routine (e.g., any of the verification routines described above in conjunction with diamond 20 of method 10) can be performed to see if the step change in slope indicates that the patient is full. In one example, a certain amount (e.g., about 100 ml to about 600 ml) is removed from the patient and then returned to the patient to see if the step change in slope still exists, thereby indicating that the patient is full. In graph 90, graph 96 corresponds to graph 92 after its verification procedure, and graph 98 corresponds to graph 94 after its verification procedure. In both graphs 96 and 98, the capacity is reduced compared to the peak capacity. That is, the capacity of about 2100 ml to 2200 ml at the peak in graph 92 is reduced to about 1500 ml at the beginning of graph 96. The capacity of about 2000 ml to 2100 ml at the peak in graph 94 is reduced to about 1500 ml at the beginning of graph 98. In graphs 96 and 98, the slope returns to substantially the same slope as before the step slope change in graphs 92 and 94, respectively, indicating that the patient has not been topped up and that the step slope change is due to other factors, in this case, a change in head height, since the IPP in graphs 96 and 98 after the routine remains at an increased amount of pressure.

[0097] Now refer to Figure 6 , which illustrates the Figure 2 1. An example system 110 of the subroutine 40 for the system 110 is shown. The system 110 includes a machine 120 (e.g., an APD machine) that operates a medical fluid processing device 170, such as a dialysis fluid cassette. The machine 120 includes a housing 122 that defines a pump interface 124 having a pump actuator or pump actuation area 126 for actuating the medical fluid processing device 170. In the illustrated embodiment, the pump actuation area 126 is pneumatically actuated via a positive pneumatic line 128 extending from a positive pneumatic source 130 to perform a pump-out stroke, for example, to (i) push fresh dialysis fluid toward the peritoneal cavity 114 of the patient 112 via a patient line 116 and a patient transfer kit 118, or (ii) push spent dialysis fluid toward a drain. In the illustrated embodiment, the pump actuation region 126 is pneumatically actuated via a negative pneumatic line 132 extending from a negative pneumatic source 134 to perform a pumping stroke, thereby drawing fresh dialysis fluid from a dialysis fluid source 140, for example, via a supply line 142, or drawing spent dialysis fluid from the peritoneal cavity 114 of the patient 112 via the patient line 116 and transfer set 118.

[0098] The machine 120 also provides a pressure sensor 144 for measuring positive pressure in the positive pneumatic line 128 and a pressure sensor 146 for measuring negative pressure in the negative pneumatic line 132. The machine 120 also includes a plurality of electrically operated pneumatic valves, such as valves 148, 150, 152, and 154. Pneumatic valve 148 is positioned in the positive pneumatic line 128 to selectively allow positive pressure from source 130 to reach the pump actuation area 126. Pneumatic valve 150 is positioned in the negative pneumatic line 132 to selectively allow negative pressure from source 134 to reach the pump actuation area 126. An exhaust valve 152 is provided in an exhaust line 154 in communication with the positive pneumatic line 128 to selectively exhaust the positive pressure in the line 128 and the pump actuation area 126 to the atmosphere. A second exhaust valve 156 is provided in an exhaust line 158 in communication with the negative pneumatic line 132 to selectively exhaust negative pressure in the line 132 and the pump actuation area 126 to atmosphere. In an alternative embodiment, a single exhaust valve and line may be provided to simultaneously exhaust both positive and negative pressures from the pump actuation area 126 to atmosphere.

[0099] The pressure sensors 144 and 146 and the pneumatic valves 148, 150, 152 and 154 are illustrated with extended dashed electrical and / or signal lines, respectively. The machine 120 is also provided with a control unit 160 having one or more processors 162 and one or more memories 164. The control unit 160 may have any one or more of a main controller, a safety controller, a video controller and / or a sub-controller or delegate controller. The control unit 160 is also illustrated with extended dashed electrical or signal lines that extend to the pressure sensors and the pneumatic solenoid valves. The control unit 160 receives pressure readings from the pressure sensors 144 and 146 and selectively opens and closes the pneumatic solenoid valves 148, 150, 152 and 154. It should be understood that the control unit 160 may be connected to additional pressure sensors, valves, fluid heaters (which are not shown to facilitate operation) and other components. Figure 6 Simplified) together.

[0100] The medical fluid treatment device 170 is provided with a pump actuation chamber 172 that mates with the pump actuation region 126 to form an overall pumping chamber. In the illustrated embodiment, the medical fluid treatment device 170 includes a flexible membrane, diaphragm, or sheet 174 that can be sized to mate with the pump actuation chamber 172 or sized to cover the entire side of the medical fluid treatment device 170 (as illustrated), wherein a portion of the membrane 174 covers the pump actuation chamber 172, and wherein this portion can be at least substantially flat or pre-arched or pre-shaped to fit into one or both of the pump actuation region 126 and the pump actuation chamber 172. The membrane 174 (or a separate membrane) may also cover or be used to actuate medical fluid valves (not shown), such as: (i) a fluid valve positioned and configured to selectively allow medical fluid to flow from the fluid source 140, through the supply line 142 and the supply channel 176 of the medical fluid handling device 170, to the pump actuation chamber 172, and (ii) a fluid valve positioned and configured to selectively allow medical fluid to flow from the pump actuation chamber 172, through the patient channel 178 of the medical fluid handling device 170, through the patient line 116, and the patient transfer kit 118, to the peritoneal cavity 114 of the patient 112. It should be appreciated that the medical fluid handling device 170 may have additional fluid valves, such as additional fluid valves for additional pump actuation chambers 172 (alternating to provide more continuous flow), and additional fluid valves for multiple supply lines 142, fluid heater lines, and / or drain lines, which are not shown to allow for the flow of medical fluid from the pump actuation chamber 172 to the patient channel 178 of the medical fluid handling device 170. Figure 6 simplify.

[0101] Control unit 160 causes negative pressure to be applied from source 134 to flexible membrane 174 to draw the sheet against the wall of pump actuation area 126 to correspondingly draw medical fluid into pump actuation chamber 172. To this end, the control unit causes valves 148, 152, and 156 to close and control valve 150 to open. During filling of pump actuation chamber 172, pressure sensor 146 measures a negative pumping pressure.

[0102] Control unit 160 causes positive pressure to be applied from source 130 to flexible membrane 174 to push the sheet against the wall of pump actuation chamber 172 to correspondingly push the medical fluid out of pump actuation chamber 172. To this end, the control unit causes valves 150, 152, and 156 to close and control valve 148 to open. During discharge of pump actuation chamber 172, pressure sensor 144 measures the positive pumping pressure.

[0103] To maintain the pump in actuated chamber 172 (filling the patient) Figure 2Subroutine 40 of takes a patient pressure reading. In one embodiment, control unit 160 closes positive pressure pneumatic valve 148 at mid-stroke, causing flexible membrane 174 to move only partially toward the wall of pump actuation chamber 172, e.g. Figure 6 . The control unit 160 causes the exhaust valve 152 to open, thereby allowing the positive pressure in the pump activation area 126 and the positive pneumatic line 128 to vent to the atmosphere. Once the positive pneumatic pressure is vented, the control unit closes the exhaust valve 152. The pressure now read by the pressure sensor 144 is the positive IPP within the peritoneal cavity 114 of the patient 112. Multiple such readings can be taken at the control unit 160 and averaged.

[0104] To maintain the pump actuation chamber 172 filled (emptied of the patient) according to Figure 2 Subroutine 40 of obtains a patient pressure reading. In one embodiment, control unit 160 closes negative pressure pneumatic valve 150 at mid-stroke so that flexible membrane 174 moves only partially toward the wall of pump actuation area 126, e.g. Figure 6 . The control unit 160 causes the exhaust valve 156 to open, thereby allowing the negative pressure in the pump activation area 126 and the negative pneumatic line 132 to vent to atmosphere. Once the negative pneumatic pressure is vented, the control unit closes the exhaust valve 156. The pressure now read by the pressure sensor 146 is the negative IPP within the peritoneal cavity 114 of the patient 112. Multiple such readings can be taken at the control unit 160 and averaged.

[0105] As described above, in one embodiment, the control unit 160 periodically repeats the pressure measurement sequence (positive or negative) during patient priming (or draining), for example, once every 100 ml to 150 ml of dialysis fluid fill, where a full pump stroke may be approximately 20 ml. The pump pause and pressure measurement sequence may, for example, take 3 to 30 seconds to complete.

[0106] The system and method of the present invention are not limited to combining Figure 6 Alternatively, for example, the machine 120 may instead provide a peristaltic pump actuator that operates in conjunction with a section of tubing provided by an alternative medical fluid handling device 170. The tubing downstream of the peristaltic pump actuator (between the actuator and the patient 112) may be provided with a pressure sensing area (e.g., a puck-like structure with a flexible sensing membrane) that is sensed by a pressure sensor located on or within the housing 122 of the machine 120 so as to contact the pressure sensing area of ​​the tubing. The control unit 160 may be programmed to pause the peristaltic pump actuator at desired intervals to allow the pumping pressure to subside and to cause the pressure sensor to instead read positive or negative patient pressure, such as IPP.

[0107] The alternative structure just described can also be used to perform Figure 3 Here, instead of pausing the peristaltic pump actuator, the control unit 160 takes continuous readings or a reading at each clock cycle of the processor 162 and performs the above-described Figure 3 The subroutine 60 of FIG. 6 includes signal analysis at block 66 and patient pressure establishment at block 68 .

[0108] Now refer to Figure 7 , a micromechanical ("MEMS") device 210 is illustrated. In the illustrated embodiment, the MEMS device 210 includes a housing 212 that holds three main components, including a power supply 214, a MEMS sensor 216, and a wireless transmitter 220, which are soldered to a small printed circuit board ("PCB") 222 located within the housing 212 and connected to each other via traces 224 along the PCB 222. The power supply 214 provides power to the MEMS sensor 216 and the wireless transmitter 220. The power supply 214 may be, for example, a 5V DC power supply and may only need to be powered during a single treatment.

[0109] As shown, the housing 212 seals and exposes the pressure sensing portion 218 of the MEMS sensor 216 so that the portion 218 can directly contact the medical fluid. The pressure signal from the MEMS sensor 216 is sent via a wireless transmitter 220 to a wireless receiver that is located within the machine 120 and is part of or in communication with the control unit 160.

[0110] Additional reference Figure 6 It is contemplated that the bottom surface of the housing 212 is connected to or coupled to the inner surface of any one or more of the patient channel 178 entering the medical fluid treatment device 170, the patient line 116 connected to the medical fluid treatment device 170, or the patient transfer kit 118 via adhesion, heat sealing, sonic welding, or molding. In any of these locations, the sensing portion 218 contacts the flowing medical fluid, enabling the control unit 160 to obtain continuous readings or readings at each clock cycle of the processor 162 via the MEMS sensor 216 and perform the above-described Figure 3 The subroutine 60 of FIG. 6 includes signal analysis at block 66 and patient pressure establishment at block 68 .

[0111] It should be understood that various changes and modifications to the preferred embodiments herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. Therefore, it is intended that such changes and modifications be covered by the appended claims.

Claims

1. A medical fluid delivery system, comprising: a medical fluid handling device comprising a patient line adapted to be placed in fluid communication with a patient; as well as A medical fluid delivery machine, comprising: a pump actuator for actuating the medical fluid handling device to move medical fluid into or out of the device; a pressure sensor positioned and disposed within the medical fluid processing device and configured to sense the pressure of the medical fluid; and a control unit in signal communication with the pressure sensor and in control communication with the pump actuator, the control unit being programmed to execute a routine during pumping, wherein the control unit: (i) determining whether at least one signal reading or a component of at least one signal reading from the pressure sensor is indicative of pressure within the patient, and (ii) determining whether to continue pumping or to stop pumping from at least one pressure signal reading or component reading indicative of pressure within the patient; wherein the pressure sensor and the control unit are configured to record continuous or semi-continuous measurements of the pressure of the medical fluid; Wherein, the control unit is configured to determine the at least one signal reading or the component of the at least one signal reading indicative of the pressure in the patient by: converting the sensed pressure of the medical fluid from a time-dependent signal into the frequency domain; and At least one frequency at which the sensed pressure of the medical fluid in the frequency domain corresponds to the pressure within the patient is determined.

2. The medical fluid delivery system according to claim 1, wherein: The medical fluid handling apparatus further comprises a patient transfer set for connection to an indwelling catheter of a patient, and wherein the pressure sensor is positioned within the patient transfer set.

3. The medical fluid delivery system according to claim 1, wherein: The medical fluid processing device further includes a pumping cassette, and wherein the pressure sensor is positioned within the pumping cassette.

4. The medical fluid delivery system according to claim 1, wherein: The pressure sensor is placed within the patient line.

5. The medical fluid delivery system according to claim 1, wherein: The pressure sensor is a micromechanical ("MEMS") sensor.

6. The medical fluid delivery system according to claim 1, wherein: The control unit is programmed to perform at least (i) or (ii) in the frequency domain.

7. The medical fluid delivery system according to claim 1, wherein: Determining whether to continue pumping or to stop pumping from the at least one pressure signal reading or the component of the at least one pressure signal reading includes evaluating a change in the at least one pressure signal reading or the component of the at least one pressure signal reading.

8. The medical fluid delivery system according to claim 1, wherein: The control unit includes at least one of the following components: (i) at least one processor, (ii) at least one memory, or (iii) at least one delegate controller.

9. The medical fluid delivery system according to claim 1, wherein: The pressure within the patient's body is the intraperitoneal pressure ("IPP").

10. The medical fluid delivery system according to claim 1, wherein: The control unit is further configured to apply at least one of a low-pass filter, a high-pass filter, a twin-T active notch filter, or a band-pass filter to the sensed pressure of the medical fluid in the frequency domain before determining at least one frequency corresponding to the pressure within the patient.

11. The medical fluid delivery system according to claim 1, wherein: The control unit is further configured to convert the sensed pressure of the medical fluid in the frequency domain into a value representative of the pressure within the patient.

12. The medical fluid delivery system of claim 1, wherein: The control unit is configured to determine to stop pumping when the at least one pressure signal reading or component reading indicative of pressure within the patient indicates that the patient's peritoneal cavity is full or nearly full with the medical fluid.

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