Systems and methods of synchronizing chest compressions with myocardial activity
Systems and method for providing chest compressions to a patient during cardiopulmonary resuscitation may include at least one ECG sensor configured to obtain ECG signals, an automated chest compressor configured to provide chest compressions and at least one processor, memory and associated circuitry of a medical device communicatively coupled with the at least one ECG sensor and the automated chest compressor. The at least one processor may be configured to receive and analyze the ECG signals, determine, based on the analysis, whether the patient is in a condition of unconscious hypotension with organized ECG, analyze, in response to a determination that the patient is in the condition of unconscious hypotension with organized ECG, the received ECG signals to detect a QRS complex, and generate an output to apply a chest compression at a predetermined time relative to the detected QRS complex.
1 . A system for providing chest compressions to a patient during cardiopulmonary resuscitation, the system comprising:
at least one electrocardiogram (ECG) sensor configured to obtain ECG signals of the patient;
at least one hemodynamic activity sensor configured to detect hemodynamic activity of the patient;
an automated chest compressor configured to provide chest compressions to the patient, the automated chest compressor being at least one of: piston based or compression belt based; and
at least one processor, memory and associated circuitry of a defibrillator device communicatively coupled with the at least one ECG sensor and the automated chest compressor, the at least one processor configured to:
receive and analyze the ECG signals of the patient,
receive and analyze signals from the at least one hemodynamic activity sensor,
determine whether the patient is in asystole based on the analysis of the ECG,
in response to determining that the patient is in asystole, transmit a signal to the automated chest compressor to begin delivering chest compressions,
in response to determining that the patient is not in asystole, determine whether a shockable cardiac rhythm is detected based on the analysis of the ECG signals,
in response to determining that a shockable cardiac rhythm is detected, initiate shock protocol,
automatically estimate a refractory period following a heartbeat for excluding R-wave identification based on the analyzed ECG signals and for withholding chest compressions during the estimated refractory period,
adjust the estimated refractory period for withholding chest compressions such that a faster heart rate results in a smaller estimated refractory period and a slower heart rate results in a longer estimated refractory period,
in response to determining that no shockable cardiac rhythm is detected, determine, based on the analysis of the ECG and hemodynamic signals, whether the patient is in a condition of unconscious hypotension with organized ECG,
analyze, in response to a determination that the patient is in the condition of unconscious hypotension with organized ECG, the received ECG signals to detect a QRS complex,
detect a slope of an ECG waveform comprising the QRS complex,
after the estimated refractory period for withholding chest compressions, identify an R-wave within the QRS complex based on the detected slope for initiating a chest compression timed according to the detected R-wave and at a predetermined time relative to the QRS complex, and
generate an output to cause the automated chest compressor to initiate the chest compressions outside of the estimated refractory period and at the predetermined time relative to the detected QRS complex based on detection of a leading edge of the R-wave of the QRS complex.
2 . The system of claim 1 , wherein the automated chest compressor is configured to apply the chest compression such that a target depth of the chest compression is achieved within a predetermined period of time relative to the QRS complex.
3 . The system of claim 2 , wherein the predetermined period of time relative to the QRS complex is within a range of approximately 125 milliseconds before a peak of an R-wave to 150 milliseconds after the peak of the R-wave.
4 . The system of claim 2 , wherein the predetermined period of time relative to the QRS complex is within a range of approximately 100 milliseconds before a peak of an R-wave to 100 milliseconds after the peak of the R-wave.
5 . The system of claim 2 , wherein the predetermined period of time relative to the QRS complex is within a range of approximately 75 milliseconds before a peak of an R-wave to 75 milliseconds after the peak of the R-wave.
6 . The system of claim 2 , wherein the target depth is a compression depth between 2 inches and 2.4 inches.
7 . The system of claim 1 , wherein the predetermined time relative to the QRS complex is within a range of from approximately 125 milliseconds before a peak of the R-wave of the QRS complex to 150 milliseconds after the peak of the R-wave.
8 . The system of claim 7 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the R-wave comprising initiating the chest compression 80 milliseconds or less before the peak of the R-wave.
9 . The system of claim 7 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the R-wave comprising initiating the chest compression 15 milliseconds or less before the peak of the R-wave.
10 . The system of claim 7 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the R-wave comprising initiating the chest compression 10 milliseconds or less before the peak of the R-wave.
11 . The system of claim 1 , wherein the predetermined time relative to the QRS complex is within a range of from approximately 100 milliseconds before a peak of the R-wave to 100 milliseconds after the peak of the R-wave.
12 . The system of claim 1 , wherein the at least one processor is configured to detect the QRS complex by identification of at least one of: a Q-wave, a P-wave, and the leading edge of the R-wave prior to occurrence of a peak of the R-wave.
13 . The system of claim 1 , wherein the at least one hemodynamic activity sensor includes at least one of: an invasive blood pressure sensor, pulse oximetry sensor, a Doppler ultrasonography sensor, a plethysmography sensor, a phonocardiography sensor, an echocardiography sensor, and a transthoracic impedance sensor.
14 . The system of claim 13 , wherein the at least one hemodynamic activity sensor includes a radio frequency sensor.
15 . The system of claim 1 , wherein the automated chest compressor comprises a compression belt and a belt tensioner configured to tighten the compression belt around the thorax of the patient in order to compress the thorax of the patient at a resuscitative rate.
16 . The system of claim 1 , wherein the automated chest compressor is a piston-based system that comprises:
a piston,
a piston driver,
support structures for supporting the piston and piston driver, and
a compression pad affixed to the piston.
17 . The system of claim 1 , further comprising a patient monitor, the patient monitor including an output device to generate audible or visual feedback to a rescuer.
18 . The system of claim 17 , wherein the visual feedback includes display of at least one of a patient's heart rate, blood pressure, ECG waveform, aortic pressure (AOP), right atrial Pressure (RAP), intracranial pressure (ICP), carotid blood flow, jugular blood flow, and an indication of an applied chest compression.
19 . The system of claim 1 , wherein the at least one processor is configured to:
determine a fiducial point based on the detected QRS complex, and
generate the output to apply the chest compression synchronized with the fiducial point comprising initiating the chest compression within a range from approximately 125 milliseconds before the fiducial point to 150 milliseconds after the fiducial point.
20 . The system of claim 19 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the fiducial point comprising initiating the chest compression within 100 milliseconds or less after the fiducial point.
21 . The system of claim 19 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the fiducial point comprising initiating the chest compression within 75 milliseconds or less after the fiducial point.
22 . The system of claim 19 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the fiducial point comprising initiating the chest compression within 50 milliseconds or less before the fiducial point.
23 . The system of claim 1 , comprising initiating the chest compression, wherein the leading edge of the R-wave occurs prior to a peak of the R-wave.
24 . The system of claim 1 , comprising initiating the chest compression at the predetermined time relative to the detected QRS complex, the predetermined time being after detection of the leading edge of the R-wave of the QRS complex and before a peak of the R-wave.
25 . The system of claim 1 , wherein the at least one hemodynamic activity sensor comprises a sensor for use in at least one of: pulse oximetry, Doppler ultrasonography, plethysmography, phonocardiography, echocardiography, and transthoracic impedance.
26 . The system of claim 1 , wherein the at least one hemodynamic activity sensor comprises a radio frequency sensor.
27 . The system of claim 1 , wherein the at least one processor is configured to generate an output to cause the automated chest compressor to hold the chest compression at a target compression depth for a predetermined hold time period after the target compression depth is reached.
28 . The system of claim 27 , wherein the target compression depth is a maximum compression depth.
29 . The system of claim 28 , wherein the predetermined hold time period comprises at least a portion of a systole period.
30 . The system of claim 29 , wherein the predetermined hold time period comprises no portion of a diastole period.
31 . The system of claim 27 , wherein the predetermined hold time period is 125 milliseconds.
32 . The system of claim 1 , wherein the slope is of the leading edge of the R-wave of the QRS complex.
33 . The system of claim 1 , wherein the detection of the R-wave comprises performing a differentiation to obtain information about the slope over time.
34 . The system of claim 33 , wherein the detection of the R-wave comprises using the obtained information about the slope over time in identifying a peak of the R-wave.
35 . The system of claim 1 , wherein the detection of the R-wave comprises performing an integration to obtain information about the slope and a width of the QRS complex.
36 . The system of claim 35 , wherein the detection of the R-wave comprises using the obtained information about the slope and the width of the QRS complex in identifying a peak of the R-wave.
37 . The system of claim 1 , wherein the at least one processor is configured to:
determine a fiducial point in the QRS complex, wherein the fiducial point occurs at a point in the QRS complex preceding a peak of the R-wave of the QRS complex; and
generate the output to apply the chest compression synchronized with the fiducial point.
38 . The system of claim 37 , wherein the fiducial point occurs at the point in the QRS complex, wherein the point in the QRS complex is in the leading edge of the R-wave of the QRS complex.
39 . The system of claim 37 , wherein the at least one processor is configured to generate the output to apply the chest compression synchronized with the fiducial point, comprising initiating the chest compression within a range from approximately 125 milliseconds before the fiducial point to approximately 150 milliseconds after the fiducial point.
40 . The system of claim 1 , wherein detecting the R-wave of the QRS complex comprises using a threshold decay rate of the ECG waveform in filtering out noise.
41 . The system of claim 40 , wherein the detecting the R-wave of the QRS complex comprises detecting whether an R-wave detection threshold has been exceeded, wherein detecting whether the R-wave detection threshold has been exceeded comprises using the threshold decay rate of the ECG waveform.
42 . The system of claim 1 , wherein the estimated refractory period is based on the patient's heart rate.
43 . The system of claim 1 , wherein the estimated refractory period is between 10-200 milliseconds.
44 . The system of claim 1 , wherein the at least one processor is further configured to determine a heart rate of the patient based on the analyzed ECG signals.