Protective effects of pulmonary surfactant on decompression sickness in rats

Decompression sickness (DCS) is a systemic pathophysiological process featured by bubble load. Lung dysfunction plays a harmful effect on off-gassing, which contributes to bubble load and subsequent DCS occurrence. This study aimed to investigate the effects of pulmonary surfactant on DCS as it possesses multiple advantages on the lung. Rats were divided into three groups: the normal (n = 10), the surfactant (n = 36), and the saline (n = 36) group. Animals in surfactant or saline group were administered aerosol surfactant or saline 12 h before a stimulated diving, respectively. Signs of DCS were recorded and bubble load was detected. The contents of phospholipid and surfactant protein A (SPA), protein, IL-1 and IL-6 in bronchoalveolar lavage fluid (BALF), and lung wet/dry (W/D) ratio were determined. Serum levels of IL-6, ICAM-1, E-selectin, GSH, and GSSG were detected. In surfactant-treated rats, the morbidity and mortality of DCS markedly decreased (P < 0.01 and P < 0.05, respectively). Survival time prolonged and the latency to DCS dramatically delayed (P < 0.01). More importantly, bubble load markedly decreased (P < 0.01). The increases of protein, IL-1 and IL-6 in BALF, and lung W/D ratio were alleviated. Restoration of total phospholipid and SPA in BALF and ICAM-1 and E-selectin in serum was observed. The inflammation and oxidation were attenuated (P < 0.01). In conclusion, prediving administrating exogenous surfactant by aerosolization is an efficient, simple, and safe method for DCS prevention in rats.NEW & NOTEWORTHY This is the first study exploring the effects of aerosol surfactant on DCS prevention and it was proven to be an efficient and simple method. The role of surfactant in facilitating off-gassing was thought to be the critical mechanism in bubble degrading and subsequent DCS prevention.