Devices for determining depth of chest compressions during CPR

• US 7,118,542 B2
• Filed: 05/12/2004
• Issued: 10/10/2006
• Est. Priority Date: 10/25/2002
• Status: Expired due to Term

• Current Assignee: Zoll Circulation Incorporated (Asahi Kasei Corporation)
• Original Assignee: Zoll Circulation Incorporated (Asahi Kasei Corporation)
• Inventors: Berger, Ronald D., Halperin, Henry R., Sherman, Darren R., Palazzolo, James Adam
• Primary Examiner(s): DEMILLE, DANTON D
• Application Number:
  US10/844,661
• Publication Number:
  US 20040210171A1
• Time in Patent Office: 881 Days
• Field of Search: None
• US Class Current: 601/41
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/339 Displays specially adapted therefor
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61H 2201/5007 computer controlled
• CPC Class Codes: A61H 2201/501 connected to external computer devices or networks
• CPC Class Codes: A61H 2201/5012 using the internet
• CPC Class Codes: A61H 2201/5043 Displays
• CPC Class Codes: A61H 2201/5048 Audio interfaces, e.g. voice or music controlled
• CPC Class Codes: A61H 2201/5058 Sensors or detectors
• CPC Class Codes: A61H 2201/5084 Acceleration sensors
• CPC Class Codes: A61H 2201/5097 wireless
• CPC Class Codes: A61H 2230/04 Heartbeat characteristics, e.g. E.G.C., blood pressure modulation
• CPC Class Codes: A61H 2230/08 Other bio-electrical signals
• CPC Class Codes: A61H 2230/40 Respiratory characteristics
• CPC Class Codes: A61H 31/005 with feedback for the user
• CPC Class Codes: A61H 31/006 Power driven
• CPC Class Codes: A61H 31/007 : Manual driven
• CPC Class Codes: A61H 31/008 : Supine patient supports or bases, e.g. improving air-way access to the lungs
• CPC Class Codes: A61M 16/00 : Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0078 : Breathing bags
• CPC Class Codes: A61N 1/39044 : in combination with cardiopulmonary resuscitation [CPR] therapy
• CPC Class Codes: G06F 2218/04 : Denoising
• CPC Class Codes: Y10S 128/901 : Suppression of noise in electric signal
• CPC Class Codes: Y10S 601/08 : Artificial respiration with computer control
• CPC Class Codes: Y10S 601/09 : including biological sensors
• CPC Class Codes: Y10S 601/10 : Artificial respiration combined with non-artificial respiration therapy

Abstract

A method of processing a raw acceleration signal, measured by an accelerometer-based compression monitor, to produce an accurate and precise estimated actual depth of chest compressions. The raw acceleration signal is filtered during integration and then a moving average of past starting points estimates the actual current starting point. An estimated actual peak of the compression is then determined in a similar fashion. The estimated actual starting point is subtracted from the estimated actual peak to calculate the estimated actual depth of chest compressions. In addition, one or more reference sensors (such as an ECG noise sensor) may be used to help establish the starting points of compressions. The reference sensors may be used, either alone or in combination with other signal processing techniques, to enhance the accuracy and precision of the estimated actual depth of compressions.

Claims

1. A device for measuring depth of chest compressions, said device comprising:

an accelerometer capable of producing an acceleration signal corresponding to the acceleration of chest compressions;

a means for integrating the acceleration signal, said means for integrating operably connected to the accelerometer, and said means for integrating capable of producing a measured depth signal corresponding to the measured depth of chest compressions; and

a processor operably connected to the means for integrating, said processor programmed to produce an estimated actual depth signal corresponding to the estimated actual depth of chest compressions by calculating an autoregressive moving average of the measured depth signal.

2. The device of claim 1 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

3. The device of claim 1 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

4. The device of claim 1 further comprising:

a means for measuring an ECG signal of a patient, said ECG signal having a noise component and an actual component;

a means for estimating the noise component of the ECG signal operably connected to the means for measuring the ECG signal and to the processor;

wherein the processor is further programmed to produce the estimated actual depth signal when the noise component of the ECG signal falls within a predetermined range.

5. The device of claim 4 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

6. The device of claim 4 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

7. The device of claim 6 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

8. The device of claim 6 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

9. The device of claim 1 further comprising a means for performing ventilation capable of ventilating the patient during CPR.

10. The device of claim 9 wherein the means for ventilation comprises a means for performing electro-ventilation.

11. A device for performing chest compressions, said device comprising:

a means for performing chest compressions on a patient;

an accelerometer capable of producing an acceleration signal corresponding to the acceleration of chest compressions;

a means for integrating the acceleration signal, said means for integrating operably connected to the accelerometer, and said means for integrating capable of producing a measured depth signal corresponding to the measured depth of chest compressions;

a processor operably connected to the means for integrating and to the means for performing chest compressions, said processor capable of producing an estimated actual depth signal corresponding to the estimated actual depth of chest compressions by calculating an autoregressive moving average of the measured depth signal;

wherein the means for performing chest compressions is capable of adjusting the depth of chest compressions based on the estimated actual depth signal.

12. The device of claim 11 wherein the means for performing chest compressions comprises an automatic chest compression device.

13. The device of claim 11 further comprising:

a means for measuring an ECG signal of a patient, said ECG signal having a noise component and an actual component;

a means for estimating the noise component of the ECG signal operably connected to the means for measuring the ECG signal and to the processor;

wherein the processor is further programmed to produce the estimated actual depth signal when the noise component of the ECG signal falls within a predetermined range.

14. The device of claim 13 wherein the means for performing chest compressions comprises an automatic chest compression device.

15. The device of claim 11 further comprising a means for performing ventilation capable of ventilating the patient during CPR.

16. The device of claim 15 wherein the means for ventilation comprises a means for performing electro-ventilation.

17. The device of claim 11 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

18. The device of claim 11 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

19. The device of claim 18 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

20. The device of claim 18 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

21. A device for measuring depth of chest compressions, said device comprising:

an accelerometer capable of producing an acceleration signal corresponding to the acceleration of chest compressions, said acceleration signal having a noise component and an actual component;

a processor operably connected to the accelerometer, said processor capable of producing, from the acceleration signal, an estimated actual acceleration signal corresponding to the estimated actual acceleration of chest compressions;

wherein the processor further comprises;

a system identifier operably connected to the accelerometer, said system identifier capable of producing an estimated noise signal corresponding to the noise component of the acceleration signal;

wherein the system identifier produces the estimated noise signal by processing the measured acceleration and at least one error source reference;

a means for combining signals operably connected to the system identifier and to the accelerometer, said means for combining signals capable of combining the acceleration signal and the estimated noise signal to produce the estimated actual acceleration signal; and

a means for integrating the estimated actual acceleration signal, said means for integrating operably connected to the processor, and said means for integrating capable of integrating the estimated actual acceleration signal to produce an estimated actual depth signal corresponding to the estimated actual depth of chest compressions.

22. The device of claim 21 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

23. The device of claim 21 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

24. The device of claim 23 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

25. The device of claim 23 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

26. The device of claim 21 further comprising:

a means for measuring an ECG signal of a patient, said ECG signal having a noise component and an actual component;

a means for estimating the noise component of the ECG signal operably connected to the means for measuring the ECG signal and to the processor;

wherein the processor is further programmed to produce the estimated actual depth signal when the noise component of the ECG signal falls within a predetermined range.

27. The device of claim 26 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

28. The device of claim 26 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

29. The device of claim 28 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

30. The device of claim 28 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

31. The device of claim 21 further comprising a means for performing ventilation capable of ventilating the patient during CPR.

32. The device of claim 31 wherein the means for ventilation comprises a means for performing electro-ventilation.

33. A device for performing chest compressions, said device comprising:

a means for performing chest compressions on a patient;

an accelerometer capable of producing an acceleration signal corresponding to the acceleration of chest compressions, said acceleration signal having a noise component and an actual component;

a processor operably connected to the accelerometer, said processor capable of producing, from the acceleration signal, an estimated actual acceleration signal corresponding to the estimated actual acceleration of chest compressions;

wherein the processor further comprises;

a system identifier operably connected to the accelerometer, said system identifier capable of producing an estimated noise signal corresponding to the noise component of the acceleration signal;

wherein the system identifier produces the estimated noise signal by processing the measured acceleration and at least one error source reference;

a means for combining signals operably connected to the system identifier and to the accelerometer, said means for combining signals capable of combining the acceleration signal and the estimated noise signal to produce the estimated actual acceleration signal; and

a means for integrating the estimated actual acceleration signal, said means for integrating operably connected to the processor, and said means for integrating capable of integrating the estimated actual acceleration signal to produce an estimated actual depth signal corresponding to the estimated actual depth of chest compressions;

wherein the means for performing chest compressions is capable of adjusting the depth of chest compressions based on the estimated actual depth signal.

34. The device of claim 33 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

35. The device of claim 33 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

36. The device of claim 35 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

37. The device of claim 35 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

38. The device of claim 33 further comprising:

a means for measuring an ECG signal of a patient, said ECG signal having a noise component and an actual component;

a means for estimating the noise component of the ECG signal operably connected to the means for measuring the ECG signal and to the processor;

wherein the processor is further programmed to produce the estimated actual depth signal when the noise component of the ECG signal falls within a predetermined range.

39. The device of claim 38 further comprising a display operably connected to the processor, and wherein the display is capable of displaying the estimated actual depth signal.

40. The device of claim 38 further comprising a means for user feedback operably connected to the processor, wherein the means for user feedback is capable of providing feedback that indicates whether chest compressions fall within a predetermined range of values.

41. The device of claim 40 wherein the processor is further capable of measuring the rate of chest compressions and wherein the means for user feedback is further capable of displaying the rate of chest compressions.

42. The device of claim 40 wherein the processor is further capable of measuring the duty cycle of chest compressions and wherein the means for user feedback is further capable of displaying the duty cycle of chest compressions.

43. The device of claim 33 further comprising a means for performing ventilation capable of ventilating the patient during CPR.

44. The device of claim 33 wherein the means for ventilation comprises a means for performing electro-ventilation.