Comparison of spot and band impedance cardiogram electrodes across different tasks.

Impedance cardiography has become of widespread interest as a noninvasive cardiovascular monitoring technique. This study compared the use of spot electrodes and two different types of band electrodes in the determination of systolic time intervals and stroke volume. EKG, impedance cardiogram, and phonocardiogram were recorded on 12 volunteers during rest, during a reaction time task, and after a short exercise task. Systolic time intervals (pre-ejection period and left ventricular ejection time) were computed on a beat-to-beat basis and on the ensemble-averaged signals. The only differences between spot and band electrodes were for impedance base level and electrode conductance. For stroke volume and the systolic time interval measures there were no differences between electrode arrays, nor were there any interactions with tasks. Correlations for stroke volume and systolic time interval measures as determined under different electrode conditions were around .8.