Interaction between peripheral blood flow and low frequency components in cardiovascular variability signals

The contribution of vasomotion to low frequency (LF, 0.03-0.14 Hz) waves in arterial pressure (AP, finger pletismography) and RR variabilities is addressed by comparing the spectra of RR, systolic AP (SAP), diastolic AP (DAP), and peripheral resistances (RES, mean AP over mean flow by laser Doppler) in the palmar region. In 22 normal volunteers, recordings were performed at rest (R) in clinostatic position and during mild exercise (EXE1, 10% maximum effort) cycling in the same position. LF predominance over the high frequency (HF, respiratory frequency) component was higher in SAP and even more in DAP than in RR; HF was virtually absent in RES. The LF central frequency shifted from 0.100 Hz for RR to 0.091 for SAP, 0.085 for DAP, and 0.073 for RES. EXE1 activated LF and inhibited HF in RR; but power and frequency relationships in vascular parameters were not significantly changed.