A COMPARISON OF ATTENUATION COMPENSATED VOLUME FLOW BASED DOPPLER ECHOCARDIOGRAPHY AND IMPEDANCE CARDIOGRAPHY IN HEALTHY-VOLUNTEERS

Attenuation compensated volume flow (ACVF) Doppler echocardiography (dual beam Doppler) measures cardiac output independently of knowledge of aortic cross-sectional area and of angle of insonation. We compared a commercially available ACVF Doppler (Vital Science, Quantascope) with impedance cardiography (BoMed, NCCOM3) in 8 healthy volunteers. Doppler and impedance readings were made during successive 30-min dobutamine infusions at rates of 1, 2 and 4 μg/kg/min. Dose-related increases were detected by both impedance and Doppler for stroke volume, cardiac output and heart rate. Total variability in the measurement of stroke volume and cardiac output was greater for Doppler than for impedance and the overall coefficient of variation for cardiac output was almost twice as high for Doppler. Within-subject variability for repeated measurements of cardiac output and stroke volume were comparable for Dopple and impedance at all infusion rates with coefficients of variation less than 10%. Component of variance analysis showed that within-subject variability contributed less than 10% to the overall variability of measurements for either technique. The greater overall measurement variability of ACVF Doppler may reflect limitations of the underlying theory or technique and further study of ACVF Doppler is required. However, it may offer no advantage over impedance cardiography for the noninvasive assessment of changes in cardiac function in healthy volunteers.