Alterations in Cutaneous Vasomotor Regulation during Acute and Chronic Hypoxia

Abstract : The effects of acute and chronic hypoxic exposure on peripheral skin blood flow were examined in six naive subjects by measuring skin blood flow in the right index finger with a laser doppler velocimeter. After baseline skin blood flows were determined, measurements of the vasoconstrictor responses to breath holding (BH), Valsalva maneuver (VM), and cold pressor test (CPT) employing ice water immersion of the contralateral hand were made. Subjects were first tested at sea level (SL), after two-hour exposure to a simulated altitude (SA) of 4300 meters (445 torr), and then tested on days 2, 3, 5, and 8 during chronic exposure at Pikes Peak, Colorado (4300 meters). Baseline and vasoconstrictor responses were not significantly altered by acute hypobaric exposure. However, during days 2-5 of chronic exposure there were significant falls in baseline peripheral skin blood flow. Similar reductions were also found in vasomotor responsiveness on days 2-5 but had recovered by day 8.