Variability and reproducibility of arterial and venous circulation parameters in the forearm and calf measured at one-week intervals.

In 12 healthy men aged 22 to 29 years the variability of basal arterial blood flow, maximal arterial blood flow as induced by a 5-min arterial occlusion, vascular resistances, total venous capacity and venous emptying rate and the reproducibility of the measurements were studied in both the upper and lower limbs 3 times at one week's interval under strictly standardised conditions using an automatic venous occlusion plethysmograph. Means, medians, standard errors, and standard deviations were virtually identical or very similar without any statistically significant difference between the 3 study occasions; this implies that valid comparisons can be made when measurements are repeated at several days' interval provided measuring conditions are rigorously standardised. Basal and maximal arterial blood flows and venous emptying rates per 100 ml of tissue were significantly higher (p less than 0.05-p less than 0.001) in the forearm than in the calf. Variability of basal blood flow in terms of standard deviations and in terms of coefficients of variation computed from duplicate determinations were significantly higher than for the other parameters and significantly more elevated in the forearm than in the calf. Variability of maximal arterial blood flow and venous emptying rate also tended to be higher in the forearm than in the leg. The high variability and low reproducibility of basal arterial flow measurements are apparently due to a high degree of random biological variability in particular concerning the forearm vascular bed which makes the forearm basal blood flow poorly suitable for studying effects of interventions in cardiovascular control.