Monitoring of cardiac arrest in a patient connected to an extracorporeal blood processing apparatus

Patent metadata

Field	Value
Publication number	US-9895109-B2
Application number	US-201414777695-A
Country	US
Kind code	B2
Filing date	Mar 17, 2014
Priority date	Mar 20, 2013
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A monitoring device ( 7 ) operates an input block ( 30 ) to acquire a pressure signal from a pressure sensor ( 6 a - 6 c ) in an apparatus for extracorporeal blood processing connected to the vascular system of the subject. A processing block ( 34 ) repeatedly processes the pressure signal for generation of a time-sequence of parameter values indicative of pressure pulsations originating from heartbeats in the subject, and an evaluation block ( 35 ) evaluates the parameter values for detection of cardiac arrest and, if cardiac arrest is detected, generates a dedicated alarm signal. To reduce the risk for false positives without increasing the risk for false negatives, the monitoring device ( 7 ) may acquire and process more than one pressure signal, and/or perform an initial viability check before the monitoring is initiated to ensure that pressure pulsations originating from heartbeats are detectable in the pressure signal(s), and/or separate the monitoring of the pressure signal(s) into a detection phase performed during regular operation of a blood pump in the apparatus, and a verification phase performed during a temporary shutdown of the blood pump.

First claim

The invention claimed is:

1. A monitoring device, comprising:
an input block configured to obtain a first pressure signal from a first pressure sensor and a second pressure signal from a second pressure sensor, the first and second pressure sensors arranged in an extracorporeal blood processing apparatus to detect pressure variations in a fluid which is pumped through a blood processing unit in the extracorporeal blood processing apparatus, wherein the extracorporeal blood processing apparatus is connected to a vascular system of a subject and includes at least one blood pumping device operable to pump blood from the vascular system through the blood processing unit and back to the vascular system;
a processing block configured to repeatedly process the first pressure signal and the second pressure signal for generation of a time-sequence of parameter values indicative of pressure pulsations originating from heartbeats in the subject; and
an evaluation block configured to (i) evaluate the parameter values according to a detection criterion for cardiac arrest, which is set to detect a disappearance of the pressure pulsations originating from the heartbeats in the first pressure signal and the second pressure signal, and, (ii) if the detection criterion is fulfilled, generate an alarm signal that signals a cardiac arrest in the subject.

2. The monitoring device of claim 1 , wherein the first pressure sensor is located on a venous side of an extracorporeal circuit of the extracorporeal blood processing apparatus, and the second pressure sensor is located on an arterial side of the extracorporeal circuit.

3. The monitoring device of claim 1 , wherein the monitoring device is further configured to generate an alarm signal for needle dislodgement upon a needle dislodgement, and wherein the alarm signal for cardiac arrest is distinguished from the alarm signal for needle dislodgement.

4. The monitoring device of claim 1 , wherein the time-sequence of parameter values includes a time-sequence of first rate values that represent a rate of the pressure pulsations originating from the heartbeats in the first pressure signal, and a time-sequence of second rate values that represent a rate of the pressure pulsations originating from the heartbeats in the second pressure signal, and wherein the detection criterion involves identifying a difference between the first and second rate values.

5. The monitoring device of claim 1 , wherein the time-sequence of parameter values includes a time-sequence of correlation values that represent a degree of correlation between the first and second pressure signals, and wherein the detection criterion involves comparing the correlation values to a correlation threshold.

6. The monitoring device of claim 1 , wherein the time-sequence of parameter values includes a time-sequence of magnitude values that represent a magnitude of the pressure pulsations originating from the heartbeats in at least the first pressure signal, and wherein the detection criterion involves comparing the magnitude values to a magnitude threshold.

7. The monitoring device of claim 1 , wherein the time-sequence of parameter values includes a time-sequence of rate values that represent a rate of the pressure pulsations originating from the heartbeats in at least the first pressure signal; and wherein the detection criterion involves at least one of: identifying a sudden change in the time-sequence of rate values; identifying, based on the time-sequence of rate values, that the rate of the pressure pulsations is substantially equal to a frequency of said at least one blood pumping device; and identifying, based on the time-sequence of rate values, that the rate of pressure pulsations is outside a predefined range, which defines physiological limits for the rate of heartbeats in the subject.

8. The monitoring device of claim 1 , wherein the time-sequence of the parameter values includes a time-sequence of statistical values that represent the shape of at least the first pressure signal and are computed as a statistical measure for signal values within a time window in at least the first pressure signal, and wherein the detection criterion involves comparing the statistical values to a statistics threshold.

9. The monitoring device of claim 1 , wherein the evaluation block includes a detection test sub-block and a verification test sub-block, wherein the monitoring device is configured to, during operation of said at least one blood pumping device, cause the detection test sub-block to evaluate the time-sequence of parameter values according to the detection criterion, and wherein the monitoring device is configured to, if the detection criterion is fulfilled, stop said at least one blood pumping device and initiate the verification test sub-block, and wherein the verification test sub-block is configured to, upon said initiation, evaluate at least the first pressure signal for absence of the pressure pulsations originating from heartbeats in the subject when said at least one blood pumping device is stopped and, upon detection of absence of the pressure pulsations, cause the evaluation block to generate the alarm signal that signals a cardiac arrest in the subject.

10. The monitoring device of claim 9 , wherein the verification test sub-block is configured to evaluate at least the first pressure signal for absence of the pressure pulsations originating from heartbeats in the subject based on the time sequence of parameter values that are generated by the processing block after said at least one blood pumping device has been stopped.

11. The monitoring device of claim 9 , wherein the input block is configured to perform a preparatory filtering to suppress pressure pulsations that originate from said at least one blood pumping device in at least the first pressure signal, and wherein the monitoring device is configured to change or disable the preparatory filtering in the input block when the verification test sub-block is initiated.

12. The monitoring device of claim 9 , wherein the detection test sub-block is further configured to, if the detection criterion is fulfilled, evaluate a confidence level of the thus-fulfilled detection criterion, wherein the detection test sub-block is configured to cause the evaluation block to generate the alarm signal if the confidence level is deemed sufficient, and wherein the monitoring device is configured to initiate the verification test sub-block if the confidence level is deemed insufficient.

13. The monitoring device of claim 9 , wherein the verification test sub-block is configured to, if being unable to detect absence of the pressure pulsations in at least the first pressure signal, initiate a configuration process for setting the detection criterion based on at least the first pressure signal.

14. The monitoring device of claim 1 , which is operable in a viability checking phase to enable the monitoring device for detection of cardiac arrest, wherein the viability checking phase includes: comparing a magnitude of the pressure pulsations that originate from the heartbeats in at least the first pressure signal to a viability threshold; and enabling the monitoring device for detection of cardiac arrest provided that the magnitude exceeds the viability threshold.

15. The monitoring device of claim 14 , wherein the viability checking phase further includes selecting at least the first pressure signal among a plurality of pressure signals obtained from a plurality of pressure sensors in the extracorporeal blood processing apparatus, based on the magnitude of the pressure pulsations originating from the heartbeats

Assignees

• Gambro Lundia Ab
• Onshage Anders

Inventors

• Hansson Per
• Olde Bo
• Solem Kristian
• Sternby Jan

Classifications

• A61B5/0215 Primary

  by means inserted into the body · CPC title

• A61M2230/04

  Heartbeat characteristics, e.g. ECG, blood pressure modulation · CPC title

• A61M1/3639

  Blood pressure control, pressure transducers specially adapted therefor · CPC title

• A61B5/02158

  provided with two or more sensor elements · CPC title

• A61B5/7282

  Event detection, e.g. detecting unique waveforms indicative of a medical condition (cough events A61B5/0823; seizures A61B5/4094; sleep apnoea A61B5/4818) · CPC title