ECG signal processor and method

An ECG signal processor for processing a measured ECG signal from a patient undergoing CPR, said patient having a chest, comprising:

• a first fast Fourier transform means for receiving a signal indicative of a CPR induced motion of the chest, and wherein the first fast Fourier transform means produces a frequency domain of said signal indicative of a CPR induced motion of the chest;
• a second fast Fourier transform means for receiving the measured ECG signal, and wherein the second fast Fourier transform means produces a frequency domain of said measured ECG signal;
• an autospectrum calculator for receiving the frequency domain of the signal indicative of the CPR induced motion of the chest, wherein the autospectrum calculator produces an autospectrum of the signal indicative of the CPR induced motion of the chest;
• a cross-spectrum calculator for receiving the frequency domain of the signal indicative of the CPR induced motion of the chest and the frequency domain of the measured ECG signal, wherein the cross-spectrum calculator produces a cross-spectrum of the signal indicative of the CPR induced motion of the chest and the measured ECG signal;
• a complex divider for receiving the autospectrum of the signal indicative of the CPR induced motion of the chest and the cross-spectrum of the signal indicative of the CPR induced motion of the chest and the measured ECG signal, said complex divider producing a frequency domain system transfer function signal by dividing the cross-spectrum of the signal indicative of the CPR induced motion of the chest and the measured ECG signal by the autospectrum of the signal indicative of the CPR induced motion of the chest;
• an inverse fast Fourier transform means for receiving the frequency domain system transfer function signal, wherein the inverse fast Fourier transform means produces a time domain transform function signal;
• a microprocessor for receiving and processing the time domain transform function signal and the signal indicative of the CPR induced motion of the chest, wherein the microprocessor produces an estimated artifact signal;
• and
• a signal adder for receiving the estimated artifact signal and the measured ECG signal, wherein said signal adder combines the estimated artifact signal and the measured ECG signal to produce an estimated true ECG signal.

An ECG signal processor for processing a measured ECG signal from a patient undergoing CPR comprising:

• a first fast Fourier transform means for receiving a signal indicative of a plurality of motions of the patient, and wherein the first fast Fourier transform means produces a frequency domain of said signal indicative of a plurality of motions of the patient;
• a second fast Fourier transform means for receiving the measured ECG signal, and wherein the second fast Fourier transform means produces a frequency domain of said measured ECG signal;
• an autospectrum calculator for receiving the frequency domain of the signal indicative of the plurality of motions of the patient, wherein the autospectrum calculator produces an autospectrum of the signal indicative of the plurality of motions of the patient;
• a cross-spectrum calculator for receiving the frequency domain of the signal indicative of the plurality of motions of the patient and the frequency domain of the measured ECG signal, wherein the cross-spectrum calculator produces a cross-spectrum of the signal indicative of the plurality of motions of the patient and the measured ECG signal;
• a complex divider for receiving the autospectrum of the signal indicative of the plurality of motions of the patient and the cross-spectrum of the signal indicative of the plurality of motions of the patient and the measured ECG signal, said complex divider producing a frequency domain system transfer function signal by dividing the cross-spectrum of the signal indicative of the plurality of motions of the patient and the measured ECG signal by the autospectrum of the signal indicative of the plurality of motions of the patient;
• an inverse fast Fourier transform means for receiving the frequency domain system transfer function signal, wherein the inverse fast Fourier transform means produces a time domain transform function signal;
• a microprocessor for receiving and processing the time domain transform function signal and the signal indicative of the plurality of motions of the patient, wherein the microprocessor produces an estimated artifact signal;
• and
• a signal adder for receiving the estimated artifact signal and the measured ECG signal, wherein said signal adder combines the estimated artifact signal and the measured ECG signal to produce an estimated true ECG signal.

An ECG signal processor for processing a measured ECG signal from a patient undergoing CPR comprising:

• a first fast Fourier transform means for receiving at least one signal indicative of a CPR induced artifact, and wherein the first fast Fourier transform means produces a frequency domain of said at least one signal indicative of a CPR induced artifact;
• a second fast Fourier transform means for receiving the measured ECG signal, and wherein the second fast Fourier transform means produces a frequency domain of said measured ECG signal;
• an autospectrum calculator for receiving the frequency domain of the at least one signal indicative of the CPR induced artifact, wherein the autospectrum calculator produces an autospectrum of the at least one signal indicative of the CPR induced artifact;
• a cross-spectrum calculator for receiving the frequency domain of the at least one signal indicative of the CPR induced artifact and the frequency domain of the measured ECG signal, wherein the cross-spectrum calculator produces a cross-spectrum of the at least one signal indicative of the CPR induced artifact and the measured ECG signal;
• a complex divider for receiving the autospectrum of the at least one signal indicative of the CPR induced artifact and the cross-spectrum of the at least one signal indicative of the CPR induced artifact and the measured ECG signal, said complex divider producing a frequency domain system transfer function signal by dividing the cross-spectrum of the at least signal indicative of the CPR induced artifact and the measured ECG signal by the autospectrum of the at least one signal indicative of the CPR induced artifact;
• an inverse fast Fourier transform means for receiving the frequency domain system transfer function signal, wherein the inverse fast Fourier transform means produces a time domain transform function signal;
• a microprocessor for receiving and processing the time domain transform function signal and the at least one signal indicative of the CPR induced artifact, wherein the microprocessor produces an estimated artifact signal;
• and
• a signal adder for receiving the estimated artifact signal and the measured ECG signal, wherein said signal adder combines the estimated artifact signal and the measured ECG signal to produce an estimated true ECG signal.

A system for facilitating the effective administration of CPR, said system comprising:

• an accelerometer for producing an acceleration signal indicative of the displacement of a chest of a patient;
• an ECG sensor for sensing, during compressions, a measured ECG signal of the patient;
• a processor operatively connected to the accelerometer and to the ECG sensor, said processor processing the acceleration signal and the measured ECG signal, wherein the processor produces an output comprising an estimated true ECG signal;
• a signaling mechanism, operably connected to the microprocessor, for indicating when the displacement of the chest is within a desired range;
• and
• a signaling mechanism, operably connected to the microprocessor, for indicating the estimated true ECG signal of the patient.

An ECG signal processing method comprising the steps of:

• receiving a measured motion signal indicative of motion of a CPR recipient's chest during the administration of CPR via a rescuer to the CPR recipient;
• receiving a measured ECG signal during the administration of CPR;
• utilizing said measured motion signal and said measured ECG signal to identify a CPR-induced artifact contained in said measured ECG signal;
• and
• producing a processed ECG signal by removing said CPR-induced artifact from said measured ECG signal.

A method of calculating an estimated true ECG signal from a patient undergoing CPR, said patient having a chest, comprising the steps of:

• providing a first input to a CPR-induced artifact identifier, said first input comprising a signal indicative of a CPR induced motion of the chest;
• providing a second input to the CPR-induced artifact identifier, said second input comprising a measured ECG signal;
• processing the first and second inputs with the CPR-induced artifact identifier to produce an estimated CPR-induced artifact signal;
• providing the estimated CPR-induced artifact signal to a signal adder;
• and
• combining the estimated CPR-induced artifact signal and the second input to produce an estimated true ECG signal.

A method of calculating an estimated true ECG signal from a patient undergoing CPR, said patient having a chest, comprising the steps of:

• providing a first input to a first fast Fourier transform means, said first input comprising a signal indicative of a CPR induced motion of the chest;
• providing a second input to a second fast Fourier transform means, said second input comprising a measured ECG signal;
• performing a fast Fourier transform on the first input to produce a frequency domain of the signal indicative of the CPR induced motion of the chest;
• performing a fast Fourier transform on the second input to produce a frequency domain of the measured ECG signal;
• providing the frequency domain of the signal indicative of the CPR induced motion of the chest to an autospectrum calculator;
• providing the frequency domain of the signal indicative of the CPR induced motion of the chest and the frequency domain of the measured ECG signal to a cross-spectrum calculator;
• calculating an autospectrum of the frequency domain of the signal indicative of the CPR induced motion of the chest with the autospectrum calculator;
• calculating a cross spectrum of the frequency domain of the signal indicative of the CPR induced motion of the chest and the frequency domain of the measured ECG signal with the cross spectrum calculator;
• providing the cross-spectrum to the numerator of a complex divider and the autospectrum to the denominator of said complex divider;
• dividing the cross-spectrum by the autospectrum with the complex divider to produce a frequency domain system transfer function signal;
• providing the frequency domain system transfer function signal to an inverse fast Fourier transform means;
• calculating a time domain system transfer function signal with the inverse fast Fourier transform means;
• providing the time domain system transfer function signal and the signal indicative of the CPR induced motion of the chest to a microprocessor;
• processing the time domain system transfer function signal and the signal indicative of the CPR induced motion of the chest with the microprocessor to produce a predicted artifact signal;
• providing the predicted artifact signal and the measured ECG signal to a signal adder;
• and
• combining the predicted artifact signal and the measured ECG signal with the signal adder to produce an estimated true ECG signal.

A method of calculating an estimated true ECG signal from a patient undergoing CPR, said patient having a chest, comprising the steps of:

• providing a first input to a processor capable of performing recursive least squares analysis, said first input comprising a signal indicative of a CPR induced motion of the chest;
• providing a second input to the processor, said second input comprising a measured ECG signal;
• and
• performing recursive least squares analysis upon the first and second inputs with the processor to produce the estimated true ECG signal.