The influence of the hand circulation on the assessment of venous distensibility of the human forearm with venous occlusion plethysmography

Aims To determine the influence of the hand circulation on the determinatio n of venous distensibility with venous occlusion plethysmography. Methods In a randomised study, duplicate measurements of forearm venous dis tensibility, with and without a wrist cuff, were made over occlusion period s of 3 and 12 min in eight volunteers. Treatments were compared with paired Student's t-tests and differences are presented as 95% confidence interval s (CI). Intra-subject variability was assessed with analysis of variance. Results Non-significant differences in increases in forearm volume between the occlusions with and without wrist cuff were found for the 3 min occlusi on (CI: -0.4, +0.2%) and the 12 min occlusion period (CI: -0.7, +0.2%). How ever, the coefficient of variation was lower with the use of a wrist cuff; after 3 min occlusion (12% vs 19%) and after 12 min of occlusion (14% vs 24 %). Forearm volume after 12 min of venous occlusion was 0.5% (CI: +0.3, +0. 7) higher than after 3 min. Conclusions Although venous distensibility was equal when assessed with and without wrist cuff exclusion of the hand circulation reduces intraindividu al variability. Equilibrium in forearm volume is not reached after 3 min pe riod of venous occlusion, as often assumed. The magnitude of the additional increase after prolonged occlusion stresses the need for well-controlled s tudies.