title: The influence of venous and arterial occlusion on capillary blood flow and transcutaneous oxygen tension in fingers.
abstract: We have previously reported a lack of correlation between the reactions of finger skin capillary blood cell velocity (CBV) and transcutaneous oxygen tension (pTcO2) to different hydrostatic pressures. In the present study the influence of different venous and arterial pressures on nailfold CBV and pTcO2 of the dorsum of the middle phalanx was investigated. In six subjects venous occlusion (50 mm Hg) was performed with the hand at heart level and 40 cm above heart level. At heart level venous occlusion caused a marked reduction in CBV from 0.59 to 0.02 mm/s (p less than 0.01) while pTcO2 was not significantly affected. When the hand was raised 40 cm above heart level CBV remained unchanged but pTcO2 fell from 58.8 to 41.8 mm Hg (p less than 0.001). Venous occlusion in this position caused a decrease in CBV and a further decrease in pTcO2. In another 5 subjects arterial occlusions of varying duration (0.5, 1, 2, 6, 15 min) were performed at the finger base. As judged by the CBV, reactive hyperemia (RH) was always present when duration of occlusion was one minute or more. Post-occlusive pTcO2 was significantly increased compared to baseline pTcO2 (p less than 0.05) only after the 15 min occlusion. Thus, there is a marked difference in the responses of CBV and pTcO2 to variations in venous and arterial pressures. The lack of response of pTcO2 to manoeuvers that result in autoregulatory adjustment of CBV probably reflects the local heating of the probe which causes maximal vasodilation in the underlying skin.
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D005260:Female; D005385:Fingers; D006801:Humans; D008297:Male; D008833:Microcirculation; D010100:Oxygen / Q000502:physiology*; D010313:Partial Pressure; D010991:Plethysmography; D011674:Pulse; D012867:Skin / Q000098:blood supply*; D012881:Skin Temperature
chemical_list: D010100:Oxygen