Impairment of the postural venoarteriolar reflex in aged individuals.

The venoarteriolar vasoconstriction reflex plays a major role in the prevention of leg oedema in the upright position in man. We studied the venoarteriolar vasoconstriction reflex with laser Doppler flowmetry in young (21 subjects, age 17-27) and very old (20 subjects, age 75-100) healthy volunteers. In the group of young volunteers, after lowering of the lower extremity 50 cm below the heart level, cutaneous blood flux decreased to 16.6% of the baseline, whereas in the group of old persons the venoarteriolar reflex was impaired and the flux decreased only to 29.2%. The difference between the two groups was statistically significant (p < 0.001). These results may explain the increased prevalence of postural oedema in old people.