Noninvasive measurement of brachial artery compliance variability

An occlusive cuff plethysmograph was utilized to noninvasively measure pressure-compliance (P-C) curves in a single human subject over extended time periods. Data was collected over a period of 22 days. In addition, compliance was examined at two different daily times to detect the existence of a circadian rhythm. The data was analyzed using standard statistical methods. It was found that the variability in compliance follows an apparently random pattern. This variation resulted in a standard deviation equal to 17% of the mean value of compliance or lumen area. Data collected over the short and long term time periods were found to possess similar variability. The variation was independent of circadian rhythm. Therefore, this instrument can be used to accurately track compliance and lumen area in patients without considering when the measurements are taken