Application of hyperbaric oxygen preconditioning to improve pilot′s lower body negative pressure tolerance

Abstract

Objective To investigate whether the preconditioning of hyperbaric oxygen (HBO) can improve the tolerance of lower body negative pressure in pilots. Methods Twenty healthy male fighter pilots were selected as subjects. The multiple HBO chamber was used and 3-time HBO exposure scheme was chosen. The chamber pressure was gradually increased to 2.5 atmospheres absolute (ATA) in 10 min and maintained for 65 min (with twice 30-min mask oxygen breathing and 5-min interval). Then the pressure was gradually reduced to 1.3 ATA in 10 min and returned to normal pressure in 5 min after staying for 5 min. Such 95-min test was undertaken once a day (set at 15∶30—17∶05) and repeated for 3 days. The lower body negative pressure tolerance was measured before and after HBO preconditioned and self-contrasted. Results The cumulative stress index was significantly increased from (-1 353.50±449.95) to (-1 843.50±522.07) by 3 rounds HBO pretreatment (t=11.10, P<0.05) and it indicated that the lower body negative pressure tolerance had been improved. Conclusions Hyperbaric oxygen preconditioning can improve the pilot′s lower body negative pressure tolerance. Key words: Acceleration; Hyperbaric oxygen; Lower body negative pressure; Preconditioning