Detecting blood path disruption in extracorpreal blood processing

• US 9,427,513 B2
• Filed: 05/23/2012
• Issued: 08/30/2016
• Est. Priority Date: 06/23/2011
• Status: Expired due to Fees

• Current Assignee: Gambro Lundia AB (Baxter International Inc.)
• Original Assignee: Gambro Lundia AB (Baxter International Inc.)
• Inventors: Holmer, Mattias, Olde, Bo, Solem, Kristian
• Primary Examiner(s): Wiest, Philip R
• Application Number:
  US14/129,087
• Publication Number:
  US 20140298891A1
• Time in Patent Office: 1,560 Days
• Field of Search: 604 401- 614
• US Class Current: 1/1
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3653 Interfaces between patient blood circulation and extra-corporal blood circuit
• CPC Class Codes: A61M 1/3655 Arterio-venous shunts or fistulae
• CPC Class Codes: A61M 1/3656 Monitoring patency or flow at connection sites; Detecting disconnections
• CPC Class Codes: A61M 1/3659 Cannulae pertaining to extracorporeal circulation
• CPC Class Codes: A61M 1/3661 for haemodialysis
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621
• CPC Class Codes: A61M 2205/13 with means for the detection of operative contact with patient, e.g. lip sensor
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3351 Controlling upstream pump pressure
• CPC Class Codes: G01N 19/00 Investigating materials by mechanical methods G01N3/00 - G01N17/00 take precedence

Abstract

A device monitors a blood path from a blood vessel access of a human subject through an extracorporeal blood processing apparatus and back to the blood vessel access. A pumping device in the blood path is operable to pump blood through the blood path from the blood withdrawal device to the blood return device. The monitoring device obtains pressure data from a pressure sensor arranged upstream of the pumping device in the blood path, and processes the pressure data for detection of a disruption of the blood path downstream of the pumping device, e.g. caused by VND (Venous Needle Dislodgement). The disruption is detected by evaluating presence/absence of cross-talk pulses at the pressure sensor, where the cross-talk pulses originate from one or more pulse generators in the extracorporeal blood processing apparatus and have propagated on a propagation path in a direction downstream of the pumping device through the blood return device, the blood vessel access and the blood withdrawal device to the pressure sensor.

Claims

1. A monitoring device for monitoring a blood path extending from a blood vessel access of a human subject through an extracorporeal blood processing apparatus and back to the blood vessel access, wherein the blood path comprises a blood withdrawal device and a blood return device for connection to the blood vessel access, and a pumping device operable to pump blood through the blood path from the blood withdrawal device to the blood return device, said monitoring device comprising:

an input for obtaining pressure data from a pressure sensor arranged upstream of the pumping device in the blood path to detect pressure pulses in the blood pumped through the blood path; and

a signal processor connected to said input and being configured to;

generate, based on the pressure data, a time-dependent monitoring signal comprising cross-talk pulses that originate from one or more pulse generators in the extracorporeal blood processing apparatus and have propagated in a direction downstream of the pumping device through the blood return device, the blood vessel access and the blood withdrawal device to the pressure sensor,

process the monitoring signal for calculation of a parameter value that indicates a presence or absence of the cross-talk pulses, and

detect, based at least partly on the parameter value, a disruption of the blood path downstream of the pumping device.

2. The monitoring device of claim 1, wherein the signal processor is configured to calculate the parameter value as a measure of irregularity of signal values within a time window of the monitoring signal.

3. The monitoring device of claim 2, wherein the measure of irregularity includes a measure of entropy of the signal values.

4. The monitoring device of claim 2, wherein the measure of irregularity includes a statistical measure of the signal values.

5. The monitoring device of claim 4, wherein the statistical measure includes a standardized moment of third order or higher.

6. The monitoring device of claim 4, wherein the statistical measure includes at least one of skewness and kurtosis.

7. The monitoring device of claim 2, wherein the signal processor is configured to generate the monitoring signal to comprise physiological pulses that originate from one or more physiological pulse generators in the human subject, and wherein the time window is selected so as to include at least part of one physiological pulse.

8. The monitoring device of claim 7, wherein the parameter value is calculated to represent a disturbance caused by the superposition of the cross-talk pulses on the physiological pulses.

9. The monitoring device of claim 7, wherein the signal processor is configured to generate the monitoring signal by filtering the pressure data to at least suppress interference pulses that originate from the pumping device and have propagated in the blood path in a direction upstream of the pumping device, wherein the filtering is configured to suppress the interference pulses such that the ratio in magnitude between the interference pulses and the physiological pulses in the monitoring signal is less than about 1/10.

10. The monitoring device of claim 1, wherein the signal processor is configured to generate the monitoring signal by filtering the pressure data with respect to interference pulses that originate from the pumping device and have propagated in the blood path in a direction upstream of the pumping device, wherein the filtering is configured to suppress the interference pulses compared to the cross-talk pulses.

11. The monitoring device of claim 10, wherein the signal processor is configured to essentially remove the interference pulses when filtering the pressure data to generate the monitoring signal.

12. The monitoring device of claim 1, wherein the signal processor is configured to generate the parameter value as a measure of magnitude of the signal values within a time window of the monitoring signal.

13. The monitoring device of any preceding claim 1, wherein the signal processor is configured to detect the disruption by comparing the parameter value to a reference, which is obtained as an estimate of the parameter value in absence of the cross-talk pulses.

14. The monitoring device of claim 13, wherein the signal processor is configured to obtain the reference based on at least one of a first, second and third basis value, wherein the first basis value is given by the parameter value calculated during a time period in which said at least one pulse generator is disabled, the second basis value is given by the parameter value calculated during a start-up procedure, in which the extracorporeal blood processing apparatus is connected to the blood vessel access via the blood withdrawal device but is disconnected from the blood vessel access downstream of the pumping device, and the pumping device is operated to pump blood from the blood withdrawal device into the extracorporeal blood processing apparatus, and the third basis value is given by the parameter value calculated during a priming procedure, in which the extracorporeal blood processing apparatus is disconnected from the blood vessel access upstream and downstream of the pumping device, and the pumping device is operated to pump a priming fluid to flow into the extracorporeal blood processing apparatus at an upstream end and out of the extracorporeal blood processing apparatus at a downstream end.

15. The monitoring device of claim 14, wherein the first basis value is generated to represent presence of physiological pulses that originate from the human subject and absence of said cross-talk pulses and absence of interference pulses that originate from the pumping device and have propagated in the blood path in a direction upstream of the pumping device;

wherein the second basis value is generated to represent one of;

presence of said physiological pulses and said interference pulses and absence of said cross-talk pulses;

presence of said physiological pulses and absence of said cross-talk pulses and said interference pulses; and

presence of said interference pulses and absence of said cross-talk pulses and said physiological pulses; and

wherein the third basis value is generated to represent presence of said interference pulses and absence of said cross-talk pulses and said physiological pulses.

16. The monitoring device of claim 1, wherein the signal processor is configured to extract shape-indicative data from the monitoring signal and calculate the parameter value by matching the shape-indicative data to reference profile data.

17. The monitoring device of claim 16, wherein the shape-indicative data comprises signal values in the monitoring signal, and the reference profile data comprises a temporal reference profile.

18. The monitoring device of claim 1, wherein said one or more pulse generators are included in a dialysis fluid circuit in hydraulic contact with the blood path, and wherein the signal processor is configured to obtain a reference signal from a further pressure sensor arranged in the dialysis fluid circuit to detect pressure pulses in a dialysis fluid pumped through the dialysis fluid circuit or from a control signal for said one or more pulse generators, and calculate the parameter value by matching the monitoring signal to the reference signal.

20. An apparatus for extracorporeal blood processing, which is configured for connection to the cardiovascular system of a human subject so as to define a blood path extending from a blood vessel access of the human subject and comprising a blood withdrawal device for connection to the blood vessel access, a pumping device operable to pump blood through the blood path, a blood processing unit, and a blood return device for connection to the blood vessel access, said apparatus further comprising the monitoring device as set forth in claim 1.

19. A device for monitoring a blood path extending from a blood vessel access of a human subject through an extracorporeal blood processing apparatus and back to the blood vessel access, wherein the blood path comprises a blood withdrawal device and a blood return device for connection to the blood vessel access, and a pumping device operable to pump blood through the blood path from the blood withdrawal device to the blood return device, said device comprising a processor executing instructions stored on a non-transitory memory to cause the device to:

obtain pressure data from a pressure sensor arranged upstream of the pumping device in the blood path to detect pressure pulses in the blood pumped through the blood path;

generate, based on the pressure data, a time-dependent monitoring signal comprising cross-talk pulses that originate from one or more pulse generators in the extracorporeal blood processing apparatus and have propagated in a direction downstream of the pumping device through the blood return device, the blood vessel access and the blood withdrawal device to the pressure sensor;

calculating, using the monitoring signal, a parameter value that indicates a presence or absence of the cross-talk pulses; and

detecting, based at least partly on the parameter value, a disruption of the blood path downstream of the pumping device.

21. A method of monitoring a blood path extending from a blood vessel access of a human subject through an extracorporeal blood processing apparatus and back to the blood vessel access, wherein the blood path comprises a blood withdrawal device and a blood return device for connection to the blood vessel access, and a pumping device operable to pump blood through the blood path from the blood withdrawal device to the blood return device, said method comprising:

obtaining pressure data from a pressure sensor arranged upstream of the pumping device in the blood path to detect pressure pulses in the blood pumped through the blood path;

generating, based on the pressure data, a time-dependent monitoring signal comprising cross-talk pulses that originate from one or more pulse generators in the extracorporeal blood processing apparatus and have propagated in a direction downstream of the pumping device through the blood return device, the blood vessel access and the blood withdrawal device to the pressure sensor;

processing the monitoring signal for calculation of a parameter value that indicates a presence or absence of the cross-talk pulses; and

detecting, based at least partly on the parameter value, a disruption of the blood path downstream of the pumping device.

22. A non-transitory computer-readable medium storing instruction for execution by a processor for an extracorporeal blood processing apparatus including a blood pump configured to pump blood through an extracorporeal blood passage and a pressure sensor monitoring a pressure in the extracorporeal blood passage, wherein the extracorporeal blood passage extends from a blood vessel access of a human subject through an extracorporeal blood processing apparatus and back to the blood vessel access, wherein the processor executes the instructions to cause the:

obtain pressure data from the pressure sensor arranged upstream of the blood pump in the blood passage, wherein the pressure data indicates pressure pulses in the blood flowing through the blood passage;

generate, based on the pressure data, a time-dependent monitoring signal which includes cross-talk pulses, wherein the cross-talk pulses originate from at least one pulse generator in the extracorporeal blood processing apparatus and have propagated through the blood flowing downstream of the pump in the blood passage;

calculating, using the monitoring signal, a parameter value that indicates a presence or absence of the cross-talk pulses; and

detecting, based at least partly on the parameter value, a disruption of the blood path downstream of the pumping device.