OBJECTIVETo investigate the effect of different pressure oxygen pre-breathing in preventing decompression sickness of rats.

METHODSForty male SD rats were randomly divided into 4 groups: decompression sickness (DCS) group and three oxygen pre-breathing groups with 1 ATA, 2 ATA and 3 ATA pressure respectively. The rats of DCS group were placed in the hyperbaric chamber and the chamber was compressed evenly within 3 minutes to depths of 7 absolute atmosphere(ATA) and held at the designated depth for 60 min, then decompressed (3 min) at constant speed to the surface pressure. After that, the rats were taken out for further detection. While the rats of oxygen pretreatment groups pre-breathed different pressure oxygen for 20 min before entering into chamber. The mortality and behavioral of rats were observed with 30 min post decompression. The dry/wet ratio of the lung, protein levels in the bronchoalveolar lavage fluid (BALF), and the inflammatory cytokine tumor necrosis factor (TNF-alpha) expression were also tested.

RESULTSCompared with that of the DCS group, the mortality and morbidity of oxygen pre-breathe groups didn't change obviously. But the total BALF protein level and the inflammatory cytokine TNF-alpha expression of 1 ATA oxygen pre-breathe group were obviously decreased, while the dry/wet ratio of lung as obviously increased instead (P < 0.05).

CONCLUSIONAlthough preoxygenation can' t obviously change the mortality and mobidity of rats, normal pressure oxygen pre-breathing can mitigate the protein infiltration in BALF and the expression of inflammatory cytokine in lung tissue.