Respiratory effects on cardiac functions measured by impedance cardiography under voluntary cardio-respiratory synchronization (VCRS)

The respiratory variations of stroke volume (SV), R-R interval and ventricle filling time were studied in supine and sitting conditions. The tests were performed under VCRS on ten male subjects. Impedance cardiography (ZCG) was used with band electrodes to measure SV. SV increased during inspiration and decreased during expiration. The data indicate that SV measured by ZCG is more related to the blood volume change of the right heart than the left heart. The results to suggest that respiration first affects the right heart filling process, which consequently influences the R-R interval and SV.