Method and apparatus for identifying disruptions to fluid communication between an extracorporeal circuit and a patient's circulatory system - Patents.com

Abstract

The system and method identify flow disruptions from an extracorporeal circuit to a patient's circulatory system based on flow data, such as from a venous line of the extracorporeal circuit. A patient contribution to the flow data is identified and monitored to assess the occurrence of a disruption between the extracorporeal circuit and the patient's circulatory system or an access device. Spectral analysis can be performed on the flow data to identify harmonics corresponding to the patient contribution, and changes or disappearance of the identified harmonics can be used to identify a flow disruption.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable.

[0003] Names of parties to the joint research agreement Not applicable.

[0004] Sequence Listing Reference Not applicable.

[0005] Statement of Prior Disclosure by Inventor or Co-Inventors Not applicable. [Technical field]

[0006] The present disclosure relates to an apparatus and method for detecting a disruption of fluid communication between an extracorporeal circuit and a patient's circulatory system, particularly for detecting a disruption in an extracorporeal circuit downstream of a blood pump of a blood treatment device, including but not limited to a venous needle withdrawal (VND), and more particularly, to an apparatus and method for identifying a disruption between a venous line of an extracorporeal circuit and a patient's circulatory system in response to a change in the patient's contribution to flow data of the extracorporeal circuit, particularly the venous line. [Background technology]

[0007] Medical procedures involving the delivery of fluids to, through, or from a patient, or any combination thereof, can range from procedures involving the transfer of blood between a patient and an extracorporeal system connected to the patient via a needle, multiple needles, or catheters inserted into the patient. For example, hemodialysis, hemofiltration, and hemodiafiltration are all treatments that remove waste products, toxins, and excess water from the blood. In these treatments, the patient is connected to an extracorporeal circuit and equipment, and blood is pumped through the extracorporeal circuit and equipment, which removes waste products, toxins, and fluids from the blood and returns the cleaned blood to the patient.

[0008] In these treatments, access devices such as needles and catheters are inserted into the patient's vascular system to allow blood to flow to and from equipment outside the body. Conventional hemodialysis, hemofiltration, and hemodiafiltration treatments can take hours, days, or even weeks, and are typically performed in a treatment facility. When treatment is performed in a treatment facility, the patient is visually monitored during hemodialysis, for example, to detect whether the needle has become dislodged. However, the needle may be in a position that is difficult for the patient or medical staff to see (e.g., when covered by a blanket), and any interruption may be detected late, which may prevent appropriate action from being taken in a timely manner.

[0009] There has also been renewed interest in self-care and home therapies such as home hemodialysis due to improved quality of life, reduced morbidity and mortality, and reduced costs compared to center-based treatments. These home therapies (whether hemodialysis, hemofiltration, or hemodiafiltration) can be performed during the day, evening, or even at night. In unsupervised situations or while the patient is asleep, there is an increased risk of disconnection due to the absence of a caregiver, and the patient may not even notice that the connection has been disconnected.

[0010] However, dialysis is a complex procedure that has traditionally been the work of a team of highly skilled professionals responsible for providing safe and effective care to patients. Recently, patients have been able to self-manage dialysis at home. However, there remain many situations that can lead to complications during dialysis. Many of these potential problems are contained by safety devices, such as alarm circuits built into dialysis machines, but needle dislodgement (including needle displacement) can go undetected or be detected very late.

[0011] In extracorporeal blood processing, it is important to minimize the risk of an extracorporeal circuit malfunction, as such malfunctions can be life-threatening for the patient. Disruption of the extracorporeal circuit downstream from the blood pump, for example due to a venous needle dislodgement (VND) from the patient or patient access, can be severe. Such a disruption can result in the loss of blood from the patient within minutes.

[0012] Specifically, for example, the connection between the extracorporeal circulation and the venous access may be impeded if the needle or cannula becomes dislodged and the connection between the extracorporeal circulation and the patient is not properly established or is cut off. In such cases, problems may arise, especially if the venous access to the patient's vascular system becomes dislodged. If the dislodgment of the venous access cannot be detected in a timely manner, blood will continue to be drawn from the patient via the arterial access, but blood after extracorporeal blood therapy will not be properly returned to the patient. For example, with a typical blood flow rate of 300 to 400 mL / min, the patient will fall into a critical condition within a few minutes.

[0013] Conventionally, the removal of an intravenous needle during blood processing could be detected based on a pressure signal from a pressure sensor ("venous pressure sensor") located downstream of the blood pump in the extracorporeal circuit. However, the pressure in the extracorporeal circuit can vary from treatment to treatment and can also change during treatment, for example due to the patient's movements during treatment, making it difficult to set an appropriate threshold. Furthermore, if the detached extracorporeal circuit gets caught on the bedsheets or the patient's clothing during treatment, the pressure measurement may not change sufficiently to indicate a potentially dangerous situation. Summary of the Invention [Problem to be solved by the invention]

[0014] Thus, a need exists for improved systems and methods for detecting disruptions in fluid connection between an extracorporeal circuit and a patient's circulatory system, particularly for detecting disruptions in an extracorporeal circuit downstream of a blood pump of a blood treatment device, including, but not limited to, intravenous needle dislodgement (VND) and lost connection to a catheter. [Means for solving the problem]

[0015] In general, the present disclosure provides an apparatus for monitoring an extracorporeal circuit extending from a patient's blood withdrawal site through an extracorporeal blood treatment device and back to a patient's blood inlet site. The extracorporeal circuit includes a blood withdrawal line extending from the patient's blood withdrawal site to the blood treatment device, a blood inlet line extending from the blood treatment device to the patient's blood inlet site, and a pump operable to pump blood through the extracorporeal circuit from the blood withdrawal line, through the blood treatment device, through the blood inlet line, and to the patient's blood inlet site. The apparatus also includes a flow sensor configured to acquire flow data of blood flow in at least one of the blood withdrawal line and the blood inlet line, and a controller in communication with the flow sensor. The controller is configured to identify a patient contribution to the flow data that is derived from the patient's physiology, and to detect a disruption of the extracorporeal blood path based at least in part on the identified patient contribution.

[0016] In one configuration, the present disclosure provides a monitoring apparatus for monitoring an extracorporeal blood pathway extending from a vascular access, through an extracorporeal blood treatment device, and back to the vascular access. The extracorporeal blood pathway includes an arterial line as a blood-out line extending from the vascular access to the blood treatment device, a venous line as a blood-in line extending from the blood treatment device to the vascular access, and a pump operable to pump blood through the extracorporeal blood pathway from the arterial line, through the blood treatment device, through the venous line, and to the vascular access. The monitoring apparatus also includes a flow sensor configured to acquire flow data of blood flow in the venous line, and a controller in communication with the flow sensor. The controller is configured to (i) identify a patient contribution to the flow data that is due to downstream patient physiology in the acquired flow data, and (ii) detect a flow interruption between the extracorporeal blood pathway and a patient based at least in part on the identified patient contribution. It is further disclosed that the control device can (i) determine a flow rate in the venous line based on the acquired flow data, (ii) identify a patient contribution to the flow rate in the determined flow rate that is due to downstream patient physiology, and (iii) detect a flow interruption between the extracorporeal blood pathway and the patient based at least in part on the identified patient contribution.

[0017] The present disclosure also contemplates that disruptions may be identified by obtaining arterial (exit) line flow data in addition to or in lieu of venous (inlet) line flow data, and may also be identified by comparing or correlating venous and arterial line flow data and from changes in such comparison or correlation of flow data.

[0018] The present disclosure also contemplates that the control device is connected to a flow sensor that senses flow data through the venous (blood supply) line of the extracorporeal circuit, and is configured to identify a disruption in the blood flow path downstream of the flow sensor in response to a change or loss of patient contribution to the venous line flow data.

[0019] Also disclosed is a method that includes identifying a disruption in connection between the venous (blood infusion) line of the extracorporeal circuit and the patient's circulatory system in response to a change or loss of patient contribution to venous line flow data.

[0020] A further method includes identifying a patient contribution in measured flow data in the venous (blood infusion) line of an extracorporeal circuit that stems from downstream patient physiology and monitoring the patient contribution to identify disruptions to vascular access.

[0021] Also provided is an additional method including the steps of measuring flow data in a venous line in an extracorporeal circuit having a pump providing flow to the venous (blood supply) line, and identifying a disruption between the venous line and the circulatory system in response to a change in a component in the measured flow data that corresponds to a physiological parameter of a circulatory system connected downstream to the venous line.

[0022] The present disclosure also includes a method for monitoring an extracorporeal blood treatment device with an extracorporeal blood circulation circuit having an arterial blood line with a patient arterial connection, a venous blood line with a patient venous connection, and a pump for transporting blood through the extracorporeal blood circulation circuit, the method including the steps of measuring blood flow data in the venous blood line of the extracorporeal blood circulation circuit, identifying a patient contribution in the measured blood flow data that corresponds to a downstream patient physiological parameter, determining the occurrence of a flow interruption between the extracorporeal circulation circuit and the patient's circulatory system in response to a change or disappearance of the patient contribution to the measured blood flow data, and generating a control signal to activate an alarm unit, stop the pump, or both after determining the occurrence of the interruption.

[0023] Hereinafter, the embodiments of the present disclosure will be described, but it should be understood that the present disclosure is not limited to the embodiments described in the present description, and various modifications are possible without departing from the basic principles of the present invention. Therefore, the scope of the present disclosure should be limited only by the scope of the attached claims. [Brief description of the drawings]

[0024] [Figure 1] Schematic diagram showing a typical extracorporeal circulation circuit [Diagram 2] Flow rate vs. time graph for venous line of extracorporeal circuit [Diagram 3] Flow vs. time graph for the arterial line of an extracorporeal circuit [Figure 4] A frequency graph showing the results of a spectrum analysis of the measured flow rate of the venous line of an extracorporeal circulation circuit. [Diagram 5] A frequency graph showing the results of a spectrum analysis of the measured flow rate in the arterial line of an extracorporeal circulation circuit. [Figure 6] A frequency graph showing the results of a spectrum analysis of the measured flow rates of the arterial and venous lines of an extracorporeal circuit. [Figure 7] A second flow rate versus time graph for the venous line of the extracorporeal circuit. [Figure 8] A second flow versus time graph for the arterial line of the extracorporeal circuit. [Figure 9] FIG. 8 is a frequency graph showing the results of a spectrum analysis (FFT) of the measured flow rate of the venous line of the extracorporeal circuit shown in FIG. 7, in which harmonics originating from the physiological function of the patient are shown. [Figure 10] A frequency graph showing the results of spectrum analysis (FFT) for the measured flow rate in the arterial line of the extracorporeal circuit shown in Figure 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring to FIG. 1, an extracorporeal circuit ("EC circuit") 100 is shown connected to a patient's circulatory system.

[0026] The extracorporeal circuit 100 extends from a blood removal site 110 of the patient, through a blood treatment device 130, and back to a blood delivery site 160 of the patient. The extracorporeal circuit also includes a blood removal line 120 extending from the blood removal site of the patient to the blood treatment device, a blood delivery line 150 extending from the blood treatment device to the blood delivery site of the patient, and a pump 170. The pump 170 is configured to pump blood through the extracorporeal circuit from the blood removal line, through the blood treatment device, through the blood delivery line, and to the blood delivery site of the patient. The flow sensor is configured to obtain blood flow data from at least one of the blood removal line 120 and the blood delivery line 150. In a particular configuration, the flow sensor 126 obtains flow data of the blood removal line 120, and the flow sensor 156 obtains flow data of the blood delivery line 150. The controller 180 is connected to at least one of the flow sensors 126, 156, and the pump 170.

[0027] In one configuration, the extracorporeal circuit 100 is configured to perform dialysis. In that case, the blood removal line 120 is referred to as an arterial line, the blood treatment device 130 includes, but is not limited to, a dialyzer, and the blood delivery line 150 is referred to as a venous line. For purposes of this specification, blood travels from the access device 200 to the arterial line 120 and back to the access device on the venous line 150. Note that although the extracorporeal circuit 100 is shown in the figures as having both an arterial flow sensor 126 and a venous flow sensor 156, it should be understood that the system of the present disclosure may be implemented without or with the arterial flow sensor.

[0028] In dialysis terminology, blood travels from the patient's blood withdrawal site 110 to an arterial line 120 (blood withdrawal line), passes through a venous line 150 (blood transfer line), and returns to the patient's blood transfer site 160. In dialysis terminology, the flow sensor 126 that acquires flow data in the arterial line is called an arterial flow sensor 126, and the flow sensor 156 that acquires flow data in the venous line is called a venous flow sensor 156.

[0029] It should be understood that although the system is shown in the figures as having both an arterial flow sensor 126 and a venous flow sensor 156, the present disclosure may be practiced using only the arterial flow sensor 126, only the venous flow sensor 156, or both the arterial and venous flow sensors.

[0030] As mentioned above, in one configuration, the extracorporeal circuit 100 is configured to perform extracorporeal blood therapy, in which the extracorporeal circuit 100 may be part of a blood treatment device 130 that removes blood from a patient, processes (e.g., treats) it, and then reintroduces it back into the patient.

[0031] Extracorporeal blood therapies include hemodialysis, hemodiafiltration, hemofiltration, plasma exchange, and the like, including the removal of toxins from the blood, such as by diffusion through a membrane.

[0032] The following terms are used in the present specification: The term "flow rate data" refers to any data from which flow rate can be derived, estimated, or calculated, and any surrogate data from which flow rate can be derived, estimated, or calculated. It is also contemplated that flow rate can be actual, calculated, or predicted blood flow, as well as any surrogate value for actual blood flow. Such surrogates include, but are not limited to, flow velocity, values ​​proportional to, or related to blood flow or flow velocity. Flow data encompasses any signal or data related to blood flow, particularly any signal or data related to the pulsatility, variability, frequency dependence, or oscillatory content or characteristics of blood flow. Flow data can be represented by any signal, such as, but not limited to, optical, acoustic, electromagnetic, temperature, or other signals on which frequency analysis can be performed. Thus, flow data includes any signal or data indicative of flow or on which flow rate, or pulsations, fluctuations, frequency fluctuations, or vibrations in flow rate, or pulsations, fluctuations, frequency fluctuations, or vibrations in flow rate, or corresponding surrogate data. For example, blood markers, such as particles native to the blood or particles introduced into the blood, may be used as surrogate data. Thus, the term flow rate is intended to encompass any value or measurement that corresponds to, is a surrogate for, or can represent blood flow, particularly blood flow pulsations, fluctuations, frequency fluctuations, vibrations, or characteristics or properties. Thus, the term "flow rate" (or "blood flow rate") encompasses volumetric flow rate, which is a measurement of the volume of liquid passing through a cross-sectional area of ​​a conduit per unit time, and may be expressed in units of volume per unit time, typically milliliters per minute (mL / min) or liters per minute (L / min), or any surrogate thereof. It should be appreciated that blood flow can be measured and calculated using any of a variety of known systems and methods.

[0033] The access device 200 is fluidly connected to a circulatory system, such as that of a human (or animal). The circulatory system includes blood, a vascular system with a cardiopulmonary system, a systemic system connecting the cardiopulmonary system to the tissues of the body, and the heart. Specifically, the systemic system pumps blood throughout the patient's body via a vascular system (arteries, veins, capillaries). Thus, the access device 200 provides access to the extracorporeal circuit 100 by fluidly connecting to the circulatory system. The term "access device" encompasses any access to a patient's circulatory system, including, but not limited to, catheters, needles, shunts, AV native fistulas, AV-artificial grafts, and venous catheters or other vascular implants. The connection of the extracorporeal circuit 100 to the patient via the access device 200 is typically a catheter or cannula or needle, e.g., a dialysis cannula, where fluid communication is established, e.g., by puncturing the access device 200. As used herein, the access device 200 encompasses the patient's blood withdrawal site 110 and the patient's blood infusion site 160. Thus, the access device 200 includes arterial and venous accesses that are separate from one another, as well as arterial and venous accesses that are proximal or adjacent to one another, or within a common shunt, line, or graft.

[0034] The term "blood treatment" refers to any blood treatment, including but not limited to dialysis. Dialysis also includes toxin removal, such as by diffusion therapy, including but not limited to hemofiltration, hemodialysis, hemodiafiltration, or Continuous Renal Replacement Therapy (CRRT). A blood treatment device is any device for performing blood treatment. Thus, in one configuration, a blood treatment device, such as a dialyzer, can be configured to controllably transfer solutes and water through a semipermeable membrane that separates the blood flow from the dialysate flow. Such transfer processes include diffusion (dialysis) and convection (ultrafiltration). Blood treatment devices can also perform any of a number of other blood treatments, such as chemical, electromagnetic, and thermal treatments.

[0035] The term blood includes processed or unprocessed blood, including synthetic and natural blood, as well as plasma.

[0036] The term "disruption" encompasses any diversion, disconnection, dislodgement, or interruption that occurs in the flow of the extracorporeal circuit 100. A disruption may be a blockage downstream of the pump 170 in certain configurations, and may be a disruption, such as a dislodged or dislodged IV needle, that may occur downstream of the blood treatment device 130 in certain configurations, as well as from the extracorporeal circuit 100 to the access device 200, or from the access device to the circulatory system (including the patient's blood withdrawal site 110 and the patient's blood infusion site 160).

[0037] The term "controller" includes signal processors and computers, including pre-programmed desktop or laptop computers, or dedicated processors. Such controllers can be easily programmed to perform the calculations described herein or their derivations to determine flow rate and convert flow data as described herein. The controller can also perform preliminary signal conditioning, such as summing one signal with another signal, or summing one signal with a portion of another signal.

[0038] The term "flow sensor" encompasses any sensor device that provides a signal representative of flow data or that provides data upon which a flow rate, flow pulsation, fluctuation, frequency change, or vibration, or a proxy for the flow rate, flow pulsation, fluctuation, frequency change, or vibration, can be determined or sensed.

[0039] The term "upstream" of a location refers to the direction against blood flow away from the location, and the term "downstream" of a location refers to the direction of blood flow away from the location. The "arterial line" or arterial line side is the portion of the extracorporeal circuit 100 through which blood flows from the patient's blood withdrawal site 110 (e.g., access device 200) to the blood treatment device 130. The "venous line" or venous line side is the portion of the extracorporeal circuit 100 through which blood flows from the blood treatment device 130 to the patient's blood infusion site 160 (e.g., access device 200).

[0040] Generally, circulation of blood through the extracorporeal circuit 100 is accomplished by a pump 170. The present disclosure encompasses extracorporeal circuits 100 in which blood treatment devices 130 (such as an extracorporeal membrane oxygenator (ECMO)) remove blood from a venous portion of a patient's circulatory system and return treated (oxygenated) blood to a second venous portion of the patient's circulatory system, as well as configurations in which blood is removed from either a venous or arterial portion of a patient's circulatory system and returned to either a venous or arterial portion of the patient's circulatory system, with it being understood that detection of disruptions may be performed in any of these configurations.

[0041] It is also contemplated that the present disclosure encompasses an extracorporeal circuit 100 having multiple patient withdrawal sites 110, multiple blood withdrawal lines 120, multiple blood treatment devices 130, multiple pumps 170, multiple blood delivery lines 150, and multiple patient blood delivery sites 160, or any combination thereof. Thus, the system may have more than one blood delivery line 150 to the patient. It is understood that for certain types of extracorporeal blood treatments, the extracorporeal circuit 100 includes an arterial needle for withdrawal and a venous needle for delivery, which are inserted into the access device 200. Thus, in an optional configuration, the extracorporeal circuit 100 is configured to withdraw blood from the access device 200 and deliver the withdrawn blood back to the access device 200. The withdrawn blood may then be treated while it is withdrawn, e.g., while it is passing through the dialyzer 130 before being delivered back to the access device 200 via the venous line 150.

[0042] In one configuration, blood passes from access device 200, through pump 170, and to a blood treatment device 130, such as a dialyzer. The blood is then pumped from blood treatment device 130 to access device 200. Although not shown, it is contemplated that venous line 150 may include an air trap and air detector between blood treatment device 130 and access device 200.

[0043] Depending on the configuration of the extracorporeal circuit 100 and the method of measuring blood parameters, an introduction port as a site for introducing a substance into the extracorporeal circuit 100 may be provided in the arterial line 120 or may be provided in the arterial line 120 .

[0044] The venous line 150 connects the flow of the extracorporeal circuit 100 to the circulatory system, such as via the access device 200. Typically, the venous line 150 includes a return (venous) cannula that provides a fluid connection to the access device 200.

[0045] The venous line 150 includes a flow sensor 156. The flow sensor 156 measures flow characteristics or parameters to generate flow data from which the flow rate or any pulsation, fluctuation, frequency change, or oscillatory components in the flow or frequency components of the flow can be determined. Thus, the flow sensor 156 can include a flow sensor for sensing the passage of an indicator through the extracorporeal circuit 100, an ultrasonic sensor, and / or a dilution sensor. The flow sensor 156 can be any of a variety of sensors for obtaining flow rate data. In an optional configuration, the flow sensor 156 (and the sensor 126) can measure various blood characteristics, including, but not limited to, temperature, Doppler frequency, electrical impedance, optical properties, density, ultrasonic velocity, glucose concentration, oxygen saturation, or other blood substances (any physical, electrical, or chemical blood properties). Alternatively, additional sensors (not shown) can be provided in addition to the flow sensor 156 to measure selected blood characteristics or properties.

[0046] As noted in the description of sensor 156, flow sensor 126 in arterial line 120 can be any of a variety of sensors. Although the system is described herein as having two sensors 126, 156, it is understood that this is for accuracy purposes and that a single flow sensor would be sufficient. It is further contemplated that pump operating parameters, such as the pump's revolutions per minute (RPM), can identify the pulsation imparted to the flow by pump 170, thereby allowing the pump contribution to be distinguished from the patient contribution.

[0047] Specifically, when the arterial line 120 includes a flow sensor 126, the flow sensor 126 can be any of a variety of sensors that obtain flow data. The sensor 126 can measure various blood characteristics, including but not limited to temperature, Doppler frequency, electrical impedance, optical properties, density, ultrasonic velocity, glucose concentration, oxygen saturation, or blood substance (any physical, electrical, or chemical blood property) that are related to, correspond to, or are indicative of blood flow and pulsation, vibration, fluctuations, frequency changes in flow, or time variations in flow. It is also understood that the flow sensor 126 can measure blood flow. Thus, in one configuration, the system includes one blood property sensor and one flow sensor. Additionally, a combination sensor that measures flow and blood parameters (characteristics) can be used.

[0048] It is also understood that the sensors 126, 156 can be located external to the extracorporeal circuit 100. That is, the sensors 126, 156 can be located at a remote location and measure changes in the blood since the introduction of the indicator, or values ​​related to the introduction of the indicator, in the extracorporeal circuit 100 and communicate or transmit this to the respective sensors by means of diffusion, electromagnetic fields, thermal fields, etc.

[0049] The pump 170 may be any of a variety of pump types, including but not limited to a peristaltic pump, roller pump, impeller pump, or centrifugal pump. The pump 170 generates a blood flow rate through the extracorporeal circuit 100. Depending on the particular configuration, the pump 170 may be controlled to establish a predetermined blood flow rate in the extracorporeal circuit 100 by direct control of the pump itself or via the controller 180. The location of the pump 170 may be any of a variety of locations within the extracorporeal circuit 100, including but not limited to the location shown in FIG. 1. In one configuration, the pump 170 is a commercially available pump that may be set or adjusted to provide any of a variety of flow rates. This flow rate may be read by a user, transmitted to and read by the controller 180, or both.

[0050] Normal (forward) blood flow through the extracorporeal circuit 100 includes blood flow removing blood from the access device 200 through the arterial line 120, blood flow sending the removed blood to the extracorporeal circuit (for treatment of the blood in the dialyzer 130), and blood flow introducing the removed (or treated) blood into the access device through the venous line 150. A pump 170 can generate blood flow from the access device 200 through the extracorporeal circuit 100 and back to the access device.

[0051] Typically, controller 180 may be connected to blood treatment device 130, pump 170, flow sensor 156, and sensor 126 (if sensor 126 is used). Controller 180 may be a stand-alone device, such as a personal computer, a dedicated device, or may be integrated into one of the components, such as pump 170 or blood treatment device 130. Although controller 180 is shown as being connected to sensors 126, 156, pump 170, and blood treatment device 130, it should be understood that controller 180 may be connected to only sensors, sensors and pumps, or any combination of sensors, pumps, and blood treatment device 130.

[0052] It has been discovered that the venous line flow data, including the flow rate of the venous line 150, not only pulsates at a frequency generally derived from the pump 170, but also contains a component corresponding to the physiological function of the patient downstream from the measurement location of the venous line flow data. That is, the venous line 150 flow data, and therefore the flow rate of the venous line 150, contain a contribution from the patient, and at least a portion of the patient contribution to the acquired flow data is due to physiological functions inside the patient further downstream. Such a patient contribution is believed to include a component derived from the pulsation of the patient's circulatory system and a respiratory component. Since the flow through the extracorporeal circuit 100 is generated by the pump 170 and the patient's physiological functions are downstream from the venous line 150, it was a surprising discovery that the venous line flow rate contains a contribution from the patient. Furthermore, as described below, it has also been discovered that the arterial line 120 flow data also contains a patient contribution, and at least a portion of the patient contribution to the acquired flow data is due to physiological functions inside the patient.

[0053] The patient contribution to the flow data arises from the patient's physiology and propagates through the access device 200. For example, if the access device is an arteriovenous (AV) shunt, it propagates through the needle, and if the access device is a catheter connected to the circulatory system, it receives a contribution from the central vein (or heart). It has been determined that the patient contribution can be observed in the flow data (e.g., blood flow) in the extracorporeal circuit 100, particularly in the form of pulsatile flow in both the arterial line 120 and the venous line 150. It is noted that the patient contribution observed in the arterial line 120 is primarily transmitted from the arterial access of the extracorporeal circuit 100, and that flow data can be obtained in the arterial line. It is also noted that any patient contribution propagating upstream from the venous line 150 to the arterial line 120 must propagate through the pump 170, the blood treatment device 130 (e.g., dialyzer), and the bubble trap (if present), each of which substantially attenuates the manifestation of the patient contribution from the venous access. That is, the patient contribution propagating upstream along venous line 150 is substantially attenuated as it propagates through pump 170, blood treatment device 130, and bubble trap (if present) into arterial line 120. Thus, the majority of the patient contribution contained in the flow data obtained from arterial line 120 is that transmitted downstream from the patient through arterial line 120. Similarly, the majority of the patient contribution observed in venous line 150 is the patient contribution that propagated upstream along venous line 150 from access device 200. Any patient contribution propagating downstream along arterial line 120 is substantially attenuated as it propagates through pump 170, blood treatment device 130, and bubble trap (if present) into venous line 150. That is, any patient contribution propagating downstream from the arterial line 120 to the venous line 150 is substantially attenuated by the pump 170, the blood treatment device 130 (dialyzer), and the bubble trap (if present), so that the patient contribution included in the flow data for the venous line 150 is dominated by the patient contribution propagating upstream along the venous line from the access device 200 (e.g., needle, venous catheter lumen, etc.).Thus, if an interruption or break occurs in the arterial access, the pump 170 will suck in air and stop blood flow through the extracorporeal circuit 100. On the other hand, if an interruption or break occurs in the venous line 150, the flow in the arterial line 120, and therefore the patient contribution in the arterial line, will not change significantly, providing a more reliable indication of the occurrence of an interruption in the venous line.

[0054] The controller 180 is programmed to identify the patient contribution to the flow data (e.g., in the blood flow rate in the venous line 150) and compare the patient contribution to the flow data between two different points in time, or to identify a change in the patient contribution in the flow data or measured flow (e.g., when the change in the patient contribution reaches a predetermined level or when the patient contribution is lost).

[0055] As shown in FIG. 2, venous flow pulsates at a frequency of approximately 68 beats per minute, which correlates with the patient's heart rate.

[0056] 3, if pump 170 is a peristaltic or roller pump type, the flow rate in arterial line 120 will pulsate and be strongly influenced by the flow fluctuations caused by pump 170. The approximately 48 beats per minute pulsation caused by pump 170 can also be determined or known from the revolutions per minute of pump 170, or from the revolutions per minute of blood treatment device 130 if pump 170 is incorporated into the blood treatment device.

[0057] It has been found that spectral analysis of the flow data in the venous line 150 can identify various contributions to the pulsatile flow rate of the extracorporeal circuit 100, including the pump contribution from the pump 170 and the patient contribution. Analysis of flow data, such as the measured flow rate, generally identifies the strength of the input signal at each frequency in the entire frequency band, which allows for the individual identification of spectral components, particularly those attributable to the patient's physiology (patient contribution). This frequency domain allows for the identification of harmonic components in the flow data, such as the measured flow rate in the venous line 150, and thus the individual identification of contributions to the pulsatile flow rate, including the patient contribution, such as a contribution corresponding to the patient's pulse rate or respiratory rate.

[0058] In general, the present disclosure allows for acquisition of flow data sufficient to allow accurate quantification (discrimination) of components of the flow data, particularly frequency domain components of the flow data. For example, flow data as a function of time is acquired at time intervals short enough to model oscillations, fluctuations, pulsations, or frequency changes in flow individually, and over a period of time sufficient to include multiple occurrences of these. The controller 180 then decomposes this flow data based on the hypothesis that the acquired signal is composed of a sum of individual oscillation components. Thus, the controller 180 can decompose a time-dependent function into a function that depends on spatial or temporal frequencies, and identify the patient contribution to the decomposed frequencies.

[0059] In one configuration, the spectral analysis can be performed by a Discrete Fourier Transform (DFT), specifically a Fast Fourier Transform (FFT). The DFT converts a time domain function into a series of sine waves of various frequencies and reconstructs the signal as a sum of such sine waves. The so-called frequency content spectrum is a frequency domain representation of a signal (e.g., a measured flow rate or a flow waveform or pulsation pattern of the flow data). Frequency analysis provides a different perspective on the flow data related to the flow in the venous line 150. Instead of looking at the flow data (i.e., flow rate in the time domain), frequency analysis breaks down the time data into a series of sine waves. The FFT is a well-known mathematical technique that converts a function of time into a function of frequency. A commercially available spectrum analyzer or a software application integrated into the controller 180 converts the flow data, such as the measured signal intensity pattern of the input signal, into frequency components in a full frequency band.

[0060] Referring to Figure 4, which is an FFT of the venous flow data of Figure 2, there is shown the first harmonic of the pump frequency derived from the flow data in venous line 150. Also shown in Figure 4 is the first harmonic of the heart rate of the patient connected to extracorporeal circuit 100, derived from the flow data in venous line 150, indicating the presence of a patient contribution that may correspond to the patient's pulse rate.

[0061] Referring to Figure 5, which is an FFT result of the arterial flow data of Figure 3, the first and second harmonics of the pump 170 are shown. It is contemplated that these harmonics may also be known or derived from the operating parameters of the pump 170, such as the revolutions per minute of the pump. It is also noted that harmonics of the heart rate are also observed in the arterial flow data. However, it is understood that even if there is an interruption in the flow between the venous line 150 and the patient's circulatory system, such as by removal of the venous needle, the harmonics of the heart rate of the arterial line 120 will still remain or be present, since a signal will propagate from the arterial access of the arterial line.

[0062] Referring to FIG. 6 , which shows an overlay of arterial and venous flow data, FFT spectral analysis confirms that contributions from the patient (heart rate) and pump 170 are observed at both flow sensors, flow sensor 126 in arterial line 120 and flow sensor 156 in venous line 150.

[0063] Thus, controller 180 is configured to identify at least one patient contribution to the flow data, such as a calculated or measured flow rate in venous line 150, by applying spectral analysis to the flow data. Controller 180 can then monitor the identified patient contribution and provide alarm notification or pump control in response to a change in the patient contribution (e.g., termination, etc.).

[0064] It should be understood that although this specification describes a Fourier transform being used to decompose the acquired flow data, other signal analysis techniques can also be used to extract information from the flow data regarding the presence or absence of patient contribution to the flow data of the extracorporeal circuit (e.g., venous line 150), particularly the presence or absence of patient contribution resulting from the patient's physiology, in order to monitor the presence or absence of patient contribution in the venous line.

[0065] Referring to FIG. 7, the flow rate of the venous line 150 is shown, including a pulsatile component. FIG. 8 is a graph showing the flow rate of the arterial line 120 of the extracorporeal circuit 100 shown in FIG. 7. FIG. 9 is a spectral analysis result of the flow rate data (specifically, the flow rate) of FIG. 7. In FIG. 10, the harmonics originating from the pump 170 are prominent and shown to be the dominant harmonics. Referring to FIG. 9, while the harmonics originating from the pump 170 are the dominant harmonics, harmonics originating from the patient's physiology, i.e., the patient contribution, can also be identified. That is, in the blood flow rate of the venous line 150, harmonics originating from downstream physiology are identified. Thus, by monitoring the disappearance or change of a predetermined amount of the patient contribution, the controller 180 can detect a disruption of flow from the venous line 150 of the extracorporeal circuit 100 to a patient's blood delivery site, such as the vascular device 200.

[0066] Thus, the system can be configured to monitor an extracorporeal circuit 100 extending from an access device 200, through an extracorporeal blood treatment device 130 (e.g., a dialyzer), and back to the access device. In this configuration, the extracorporeal circuit includes an arterial line 120 extending from the access device to the blood treatment device, a venous line 150 extending from the blood treatment device to a vascular access, and a pump 170 connected to the extracorporeal circuit to pump blood from the access device into the extracorporeal circuit, from the arterial line, through the blood treatment device, through the venous line, and back to the access device. The system also includes a flow sensor 156 for acquiring flow data of blood flow in the venous line 150, and a controller in communication with the flow sensor, the controller 180 being configured to determine the flow rate in the venous line based on the flow rate data, identify at least one patient contribution to the determined flow rate resulting from downstream physiological phenomena of the patient by spectral analysis, particularly FFT, and detect a disruption in the extracorporeal blood circulation path downstream of the pump 170 based at least in part on the identified patient contribution. That is, the controller 180 can be configured to identify the disappearance of a previously identified patient contribution as indicated by the spectral analysis result. Identifying the disappearance of the patient contribution from the spectral analysis result in this way can be used to identify a disruption in the flow from the extracorporeal circuit 100 to the access device 200 (or circulatory system) and to issue an alarm, stop the pump 170, or both. As mentioned above, such a disruption can include removal of the intravenous needle.

[0067] The controller 180 can perform the above-mentioned transformations to obtain and even compare (monitor) the frequency components. However, it is understood that configurations in which data points are selectively obtained, but because a continuous waveform is required to perform Fourier analysis, the controller 180 can also apply predictive models (such as, but not limited to, AI algorithms) to these spaced data points in addition to the above-mentioned transformations to generate, for example, expected waveform patterns, etc., which can identify disruptions as soon as changes are identified in the time domain. Thus, the controller 180 can identify changes in the patient contribution in the frequency domain, the time domain, or both. It is further contemplated that the controller 180 can identify changes in the correlation between the flow data (e.g., flow waveform patterns) obtained or expected from either or both of the arterial and venous lines and the next obtained or expected pattern (e.g., the pattern that will emerge from the next heart beat).

[0068] The controller 180 can be configured to improve identification of the patient's physiological parameter(s) in the flow data of the blood supply (venous) line 150, such as by correlating the flow data between the blood supply (venous) line and the blood supply (arterial) line 120. For example, the controller is configured to identify at least one patient's physiological parameter (patient contribution) or a change in the patient's physiological parameter from a relationship between the blood supply (venous) line flow data and the blood supply (arterial) line flow data, with one flow sensor 156 operably connected to the blood supply (venous) line 150 to generate the blood supply line flow data and a second flow sensor 126 operably coupled to the blood supply (arterial) line 120 to generate the blood supply line flow data. In one configuration, the relationship is a correlation between the blood supply (venous) line flow data and the blood supply line flow data.

[0069] It will further be appreciated that the controller 180 can receive information from the blood treatment device 130, the pump 170, or both, such as blood flow or revolutions per minute settings, and distinguish between the transform (Fourier) components of the acquired flow data to distinguish between flow data generated by the pump 170 and flow data generated due to patient contributions to the flow data (such as the patient's heart rate).

[0070] It is contemplated that controller 180 is connected to flow sensor 156, which senses flow through venous line 150. Controller 180 is configured to identify disruptions in the blood flow path downstream of the flow sensor in response to changes in the patient contribution to the flow rate in venous line 150. Such changes in the patient contribution to the flow rate data (i.e., flow rate) in venous line 150 can be detected by changes in the patient contribution, which are manifested as changes in harmonics detected by spectral analysis, and by temporary flow spikes that appear when the venous line is exposed to atmospheric pressure rather than the pressure within an access device 200, such as an venous access. It is contemplated that when venous line 150 is exposed to atmospheric pressure, the resistance to blood flow in the venous line is reduced, and a corresponding spike in blood flow can be detected.

[0071] The system provides a method that includes identifying a disruption (e.g., by an access device 200) between the venous line 150 of the extracorporeal circuit 100 and the patient's circulatory system, where such disruption is accompanied by a change in the patient contribution to the flow rate of the venous line, which corresponds to a change in harmonics identified in the spectral analysis, which harmonics arise from downstream patient physiology.

[0072] The system also provides a further method including identifying at least one patient contribution in the measured flow rate of the venous line 150 of the extracorporeal circuit 100 resulting from downstream patient physiology, and monitoring the patient contribution to identify disruptions in vascular access between the extracorporeal circuit 100 and the circulatory system. The monitoring step can include monitoring for the presence or absence of harmonics, as well as monitoring the rate of change of waves identified as harmonics or the value of the harmonics relative to a predefined level or threshold.

[0073] The disclosed method includes measuring the flow rate in venous line 150 and identifying a disruption in communication between the venous line and the patient's circulatory system in response to a change in a component of the flow rate that corresponds to a physiological parameter of the circulatory system connected downstream to the venous line, which change in the component can be detected by a corresponding change in a spectral analysis of the measured flow rate in venous line 150.

[0074] The present disclosure thus provides for monitoring an extracorporeal blood treatment device 130 including an extracorporeal circuit 100. The extracorporeal circuit includes an arterial line 120 with a patient arterial connection, a venous line 150 with a patient venous connection, and a pump 170 for transporting blood through the extracorporeal circuit. The method includes measuring a flow rate in the venous line 150 of the extracorporeal circuit 100, identifying at least one patient contribution in the measured flow rate that corresponds to a downstream patient physiological parameter, and determining the occurrence of a flow disruption between the extracorporeal circuit and the circulatory system in response to a change in the patient contribution to the measured flow rate. The step of identifying the patient contribution includes identifying frequencies that correspond to downstream patient physiology through a spectral analysis, and a change in the identified frequencies can trigger an alarm or a change in pumping state of the pump 170.

[0075] The present disclosure describes systems and methods for determining whether there is an interruption in flow from the extracorporeal circuit 100 to the patient's circulatory system, such as when a needle or cannula becomes dislodged from the patient or when a blood treatment device 130 is disconnected from an IV needle or venous catheter lumen. That is, an interruption in flow from the extracorporeal circuit 100 to the patient's circulatory system includes an interruption in flow within the extracorporeal circuit downstream of the pump 170. For example, such interruptions may include an interruption in flow from the pump to the venous line 150, or from the blood treatment device 130 to the venous line, as well as an interruption between the venous line and the patient access, or from the patient access 200 to the circulatory system.

[0076] One of the primary applications of the present system and method is blood therapy, in which blood is removed from a patient, treated, and the treated blood is returned to the patient. As mentioned above, typical blood therapies include hemodialysis ("HD") systems, hemofiltration ("HF") systems, hemodiafiltration ("HDF") systems, and continuous renal replacement therapy ("CRRT") systems, all of which remove blood from a patient, filter the blood, and then return the blood to the patient. However, it is understood that the access disruption detection system and method described herein can be used in these blood therapies as well as in cardiopulmonary bypass surgery, in which blood is removed from a patient, oxygenated, and then returned to the patient. Furthermore, the present disruption detection method can also be used in single-needle systems, such as certain types of drug delivery systems that infuse medication from a source into a patient. Additionally, the present disruption detection method can also be used in systems that separate and collect blood (e.g., to separate platelets, plasma, red blood cells, or cell subpopulations), such as single-needle or dual-needle apheresis therapy.

[0077] Accordingly, the present disclosure provides a method that includes (a) identifying a patient contribution in flow data of a blood line of an extracorporeal circuit that is due to downstream patient physiology, and (b) monitoring the patient contribution to identify disruptions to flow from the extracorporeal circuit to the patient's circulatory system, and may further include generating an alert or alarm upon identifying a vascular access disruption.

[0078] Accordingly, the present disclosure provides a method including: (a) acquiring flow data for a blood supply line flow in an extracorporeal circuit having a pump providing flow to the blood supply line; and (b) identifying a disruption in connection between the extracorporeal circuit and a downstream patient's circulatory system in response to a change in a component of the flow data that corresponds to a physiological parameter of the downstream patient's circulatory system.

[0079] The present disclosure further provides a method for monitoring an extracorporeal blood treatment device including an extracorporeal circuit having an arterial line with a patient arterial connection, a venous line with a patient venous connection, and a pump for transporting blood through the extracorporeal circuit. The method includes the steps of: (a) sensing blood flow data in the venous line of the extracorporeal circuit; (b) identifying a patient contribution in the sensed blood flow data that corresponds to a downstream patient physiological parameter; and (c) determining a disruption of blood flow from the venous line in response to the identified change in the patient contribution to the sensed blood flow data. The method may also further include, after determining the occurrence of the disruption, generating a control signal to activate an alarm unit, stop the pump, or both.

[0080] Although the present disclosure has been described in detail above, particularly with reference to one embodiment, it will be understood that variations and modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. The scope of the present invention is defined by the appended claims, and it is intended to embrace all modifications that do not depart from the meaning and scope of equivalents. [Explanation of symbols]

[0081] 100 Extracorporeal circulation circuit, extracorporeal blood circulation circuit 110 Patient's blood drainage site 120 Arterial line, blood drainage line 126 Arterial Flow Sensor 130 Blood treatment devices, dialysis machines 150 Intravenous lines, blood supply lines 156 Venous Flow Sensor 160 Patient blood supply site 170 Pump 180 Control device 200 Access Devices, Vascular Devices, Patient Access

Claims

1. A system for detecting a disruption of fluid communication between an extracorporeal circuit and a patient's circulatory system, the system comprising: (a) an extracorporeal circulation circuit extending from a blood withdrawal site in a patient, through an extracorporeal blood treatment device, and back to a blood infusion site in the patient; a blood removal line extending from a blood removal site on the patient to the blood treatment device; a blood delivery line extending from the blood treatment device to a blood delivery site on the patient; an extracorporeal circuit comprising: a pump operable to pump blood through the extracorporeal circuit from the blood removal line, through the blood treatment device, through the blood delivery line, and to a blood delivery site in the patient; (b) a flow sensor configured to acquire flow rate data of blood flow in at least one of the blood removal line and the blood return line; (c) a controller in communication with the flow sensor, (i) identifying a patient contribution to the flow data that results from a patient's physiology, the patient contribution including a physiological parameter of the patient; (ii) upon detecting a disruption of fluid communication between the extracorporeal circuit and the patient's circulatory system, transmitting a control signal configured to instruct the system to at least one of activate an alarm unit or stop the pump based at least in part on the determined patient contribution. A control device configured as above, A system comprising:

2. The system described in claim 1, wherein the identified patient contribution is the frequency of the flow data in the frequency domain of the flow data.

3. The system described in claim 1, wherein the identified patient contribution is a patient-generated component of the flow rate of the blood supply line.

4. The system described in claim 1, wherein the control device is configured to determine the flow rate of the blood supply line based on the flow rate data.

5. The system described in claim 1, wherein the interruption is the removal of an intravenous needle.

6. The system described in claim 1, wherein the blood treatment device is a dialysis machine.

7. The system of claim 1, wherein the control device is configured to stop the pump in response to detecting the disruption.

8. The system described in claim 1, wherein the flow sensor acquires the flow rate data from the blood supply line.

9. The system of claim 1, wherein the control device is configured to generate an alarm signal and a pump stop signal in response to detecting the disruption.

10. The system described in claim 1, wherein the control device is configured to identify the patient contribution by spectral analysis of the flow data.

11. The flow sensor is operably connected to a blood line; the system further comprising a second flow sensor operably coupled to the blood removal line to generate blood removal line flow data; The system of claim 1 , wherein the controller is configured to determine the patient contribution based on the blood removal line flow data and the flow data.

12. The system of claim 1, wherein the control device is configured to identify a contribution to the flow data corresponding to the pump.

13. A method for detecting a disruption of fluid communication between an extracorporeal circuit and a patient's circulatory system, the method comprising: (a) monitoring an extracorporeal circuit extending from a patient's circulatory system, through a site of blood withdrawal from the patient, to an extracorporeal blood treatment device, through a site of blood infusion from the patient, and back to the patient's circulatory system, the extracorporeal circuit comprising: a blood removal line extending from a blood removal site on the patient to the blood treatment device; a blood delivery line extending from the blood treatment device to a blood delivery site on the patient; a pump configured to pump blood through at least a portion of the extracorporeal circuit; (b) identifying a patient contribution to the flow data that results from the patient's physiology; (c) detecting a loss of connection between the blood supply line of the extracorporeal circuit and the patient's circulatory system in response to one of a change and a loss of the patient contribution to the flow rate data of the blood supply line; (d) transmitting a control signal configured to at least one of activate an alarm unit or stop the pump when a disconnection between the blood line of the extracorporeal circuit and the patient's circulatory system is detected; A method comprising:

14. The method described in claim 13, wherein the patient contribution is a harmonic in a frequency domain function of the flow data.

15. The method described in claim 13, wherein the patient contribution corresponds to a physiological parameter of the circulatory system located downstream from the blood supply line.

16. The method described in claim 13, wherein the patient contribution is the frequency of the flow data in the frequency domain of the flow data.

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