Method of determining depth of chest compressions during CPR

• US 20070010764A1
• Filed: 06/20/2006
• Published: 01/11/2007
• Est. Priority Date: 10/25/2002
• Status: Active Grant

• Current Assignee: Zoll Circulation Incorporated (Asahi Kasei Corporation)
• Original Assignee: Zoll Circulation Incorporated (Asahi Kasei Corporation), ZOLL Corporation Incorporated
• Inventors: Berger, Ronald, Halperin, Henry, Palazzolo, James, Sherman, Darren
• Granted Patent: US 8,096,962 B2
• Time in Patent Office: Days
• 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 compressing a chest of a patient, said device comprising:

a means for performing chest compressions on a patient;

a means for performing defibrillation operably connected to the means for performing chest compressions;

a means for sensing the ECG signal of the patient, said means for sensing the ECG signal capable of producing a measured ECG signal corresponding to the measured value of the ECG signal of the patient, wherein the ECG signal comprises an actual component and a noise component;

a compression sensor operably connected to the means for performing chest compressions, said compression sensor capable of producing a compression signal corresponding to the presence of a chest compression;

a processor operably connected to the compression sensor and to the means for sensing the ECG signal, said processor capable of producing an estimated actual ECG signal corresponding to the estimated actual ECG signal of the patient and capable of performing defibrillation shocks to the patient using the means for defibrillation without stopping chest compressions being performed by the means for performing chest compressions.

2. The device of claim 1 wherein the compression sensor comprises a load sensor.

3. The device of claim 2 wherein the load sensor is disposed beneath the patient.

4. The device of claim 2 wherein the compression sensor comprises a means for measuring the displacement of a compression belt.

5. The device of claim 4 wherein the means for measuring the displacement of a compression belt comprises an encoder.

6. The device of claim 5 wherein the encoder comprises a rotary encoder.

7. The device of claim 5 wherein the encoder comprises an optical encoder.

8. The device of claim 1 wherein the compression sensor comprises an accelerometer.

9. The device of claim 1 wherein the processor is further programmed to perform defibrillation shocks based on the estimated actual ECG signal.

10. The device of claim 1 wherein the processor is further programmed to begin chest compressions before shocking the patient with the means for performing defibrillation.

11. The device of claim 1 wherein the means for performing chest compressions comprises an automatic chest compression device.

12. The device of claim 1 further comprising a display operably connected to the processor wherein the display is capable of displaying the estimated actual ECG signal.

13. The device of claim 1 further comprising a means for providing user feedback operably connected to the processor, wherein the means for performing user feedback is capable of providing feedback that indicates whether the patient requires defibrillation.

14. The device of claim 1 wherein the processor is programmed to estimate a value of the patient'"'"'s transthoracic impedance and use the value of the patient'"'"'s transthoracic impedance to determine an amount of energy used to shock the patient with the means for performing defibrillation.

15. A method of performing CPR on a patient, wherein the method comprises the steps of:

compressing the chest of the patient;

providing a means for measuring the ECG of the patient;

wherein the means for measuring the ECG of the patient is capable of measuring an ECG signal of the patient during compressions, said ECG signal comprising a noise component and an actual component and of producing;

wherein the means for measuring the ECG of the patient is further capable of determining an estimated actual ECG signal during the chest compression of the patient;

producing the estimated actual ECG signal during the chest compressing; and

applying a defibrillation shock to the patient during a chest compression based on the estimated actual ECG signal.

16. The method of claim 15 comprising the further steps of:

providing a reference sensor capable of identifying the start of a compression;

identifying a compression with the reference sensor; and

applying the defibrillation shock at a predetermined point in a compression cycle.

17. The method of claim 15 comprising the further step of:

varying energy applied to the patient by the defibrillator based upon the patient'"'"'s transthoracic impedance.

18. A method of performing CPR on a patient, wherein the method comprises the steps of:

providing a CPR device comprising a means for performing chest compressions on a patient and a means for performing defibrillation;

wherein the device is capable of measuring an ECG signal of the patient during compressions, said ECG signal comprising a noise component and an actual component and of producing;

wherein the device is further capable of determining an estimated actual ECG signal during the chest compression of the patient;

performing chest compressions on the patient with the CPR device;

producing the estimated actual ECG signal during the chest compressing; and

applying a defibrillation shock to the patient during the chest compression based on the estimated actual ECG signal.

19. The method of claim 18 comprising the further steps of:

providing a reference sensor capable of identifying the start of a compression;

identifying the start of a compression with the reference sensor; and

calculating estimated actual depth of compressions when the start of a compression has been identified.