Development of forearm impedance plethysmography for the minimally invasive monitoring of cardiac pumping function

Abstract

It is essential to continuously and non-invasively monitor the cardiac pumping function in clinical setting. Thus, the study aimed to explore a regional impedance phethysmographic method to assess the changes in stroke volume. To do this, we developed a plethysmographic device that was capable of delivering a single-frequency current with constant amplitude and of recording electrical impedance signals of biological tissue. The electrical impedance plethy- smographic waveform form the lower arm was measured with the impedance plethysmographic device, and simultaneously the end-systolic and end- diastolic volumes of the left ventricle were obtained with a two-dimension echocardiographic system in fourteen healthy subjects before and immediately after a thirty-second breath-hold maneuver. For the 14 subjects, a linear correlation coefficient of 0.79 (p < 0.001) was obtained between the changes in peak amplitude of the forearm impedance waveform and the changes in stroke volume before and just after the breath-hold test. In addition, the changes in the mean area under the impedance curve and the change in stroke volume were also correlated linearly (r = 0.71, p < 0.005). In summary, the forearm impedance plethysmography may be employed to evaluate the beat-to-beat alteration in cardiac stroke volume, suggesting its potential for long-term monitoring cardiac pumping performance