On the relationship between regional circulation and systemic blood pressure

Objectives: The relationship between regional circulation (blood flow or calculated resistance) and systemic blood pressure (BP) is only poorly documented in the range of intermediate to low BP. Methods: In 75 subjects covering the BP range from low, over intermediate, to high BP, venous occlusion plethysmographic recordings were performed at the calf and finger vessels. Correlations were calculated between regional blood flow or vascular resistance and BP defined from office and from 24 h ambulatory BP registrations, at rest and during reactive hyperaemia. Results: At any BP level, finger blood flow at rest and during reactive hyperemia was higher than calf blood flow, and resistance was lower. The interval of 90-100 mmHg office diastolic BP was characterized by significantly (p < 0.001) higher resting finger blood flow; the increase in resting muscle blood flow was less pronounced. At rest and during reactive hyperaemia there was a stepwise increase in calf regional vascular resistance in parallel with increasing BP. For the finger circulation, increased vascular resistance was only observed for the higher BP values. Correlations between calf and finger vascular resistances and BP were positive and highly significant over the whole BP range, both for office (0.650 < r < 0.776) and for ambulatory BP (0.531 < r < 0.781). These correlations remained significant after adjustment for the age dependency. Increases in calf and finger blood flow induced by arterial occlusion were highest for the lowest BP quintiles. Conclusions: Our data further indicated that the capacity to dilate decreased progressively with increasing BP level (from asymptomatic low to high BP) for both calf and finger circulation.