The effect of postural changes upon the ankle arterial perfusion pressure.

The normal arterial blood pressure at the ankle, (AP), right brachial arterial pressure (RBP) and pressure index (PI) were investigated in 50 healthy young volunteers under basal conditions and during certain positions of the legs, utilizing Doppler ultrasound flow determination and standard size blood pressure cuff. The mean AP was 10 mm Hg higher than the mean RBP in 76 instances but AP was smaller than RBP in 24 out of 100 investigated lower extremities. Mean PI was 1.069+/-0.158. There was no statistically significant difference between PI of heavier and leaner patients although increased weight was associated with a significantly higher brachial and ankle arterial pressure. Departure of the lower extremity from the horizontal position resulted in AP changes explained by gravitational effects. If the new posture was maintained, the new AP persisted, thus indicating an absence of significant corrective circulatory adaptation to the posture changes. Extreme flexion of hip and knee joints resulted in a marked decrease of AP and PI, suggesting arterial kinking. This change was not affected by the weight:height ratio of the subject. It is concluded, therefore, that the presence of a greater amount of periarterial soft tissues does not significantly prevent arterial kinking. These tensional shifts indicate changes of flow pattern occurring in normal subjects during extreme flexion. Even more marked shifts can be anticipated in arteriosclerotic patients under similar circumstances.