Impedance cardiac profile monitoring by a modified ensemble averaging technique

A real-time algorithm is developed to modify the ensemble averaging so that it averages nonperiodic signals, such as ECG (electrocardiogram), dz/dt, Delta z, etc., for impedance cardiac profile monitoring. A real-time algorithm is developed top detect R spikes adaptively from ECG signals. A signal preprocessor is developed to process signals digitally before any further work is done. This method reduces muscle noise, 60-Hz interference, and respiration effect. 144 sets of data from five healthy volunteers, four critically ill patients and three healthy exercising volunteers have been tested. Correlation studies between the authors' system and standard hand calculation of stroke volume, based on Kubiceks equations, show relatively high and stable correlation coefficients; r=0.93, p<0.005 (healthy); r=0.94, p<0.002 (ill); r=0.95, p<0.002 (exercise). Apnea is not necessary during any of the studies.<
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