Relative contributions of spontaneous and centrally driven vasomotion in the overestimation of blood pressure variability at the finger

Previous studies showed that nearly 30% of the VLF (0.01-0.04 Hz) power of systolic arterial pressure measured by the Finapres device (F-SAP) is uncorrelated to the brachial intra-arterial signal, this being likely due to the interfering effect of both local and centrally-driven vasomotion of small arteries under the finger cuff upon the measurement process. In this study we estimated the relative weight of these two contributions using a simple linear model of the relationship between intra-arterial and finger signals. We found that VLF fluctuations of F-SAP in contralateral fingers are highly correlated (coherence >0.86, mean±D: 0.93±0.04) and that the contribution of centrally-driven disturbances to F-SAP was about 6 times that of local disturbances. Spectral indices in the VLF, LF (0.04÷0.15) and HF (0.15÷0.4) bands were very similar in contralateral fingers.