Arterial Oxygen Pressure Following Whole-Body Vibration at Altitude

Hansen TAS, Kåsin JI, Edvardsen A, Christensen CC, Wagstaff AS. Arterial oxygen pressure following whole-body vibration at altitude. Aviat Space Environ Med 2012; 83:431–5.

Introduction: Most helicopter operations are carried out at altitudes below 10,000 ft. At these altitudes, the risk of the crew experiencing hypoxia is low. For that reason, supplementary oxygen is not standard equipment on board most helicopters. Due to developments in military missions, high-altitude operations have become more frequent—as have the chances of the crew experiencing hypoxia. Helicopter crews are subjected to a higher load of whole-body vibration compared to fixed-wing aircraft crews. Whole-body vibration increases muscle work, with increased oxygen consumption as a result. We hypothesized that whole-body vibration, as experienced by helicopter crews, causes additional lowering of arterial oxygen levels under hypoxic conditions. Methods: Data were collected from 10 subjects. They were all exposed to six different pressure altitudes in a hypobaric chamber, ranging from 1000 ft to 16,000 ft (∼305 m to ∼4877 m). Arterial blood samples were drawn on two occasions at each altitude: after 14 min of rest and followed by 15 min of whole-body vibration (17 Hz, at 1.1 m · s^−2, in the z-axis) at each altitude. Results: There was no significant effect of whole-body vibration on arterial oxygen pressure at altitudes up to 16,000 ft (∼4877 m), nor was there any effect on ventilation, seen as changes in arterial pressure of CO₂. Discussion: We contribute the lack of effect to the low vibration intensity used in this study. Since this vibration intensity was higher than experienced by helicopter crews during flight, we conclude that whole-body vibration does not contribute to hypoxia during high-altitude operations in helicopters.