Changes of divers′ pulmonary functions in 150 m heliox saturation-182 m excursion diving in the open sea

Objective To determine the changes of divers′ pulmonary functions in response to the prolonged hyperbaric exposure in saturation diving.Methods 8 male navy divers took part in a single 150 m heliox saturation 182 m excursion diving in the South China Sea.Dynamic pulmonary functions were measured before diving,during compressing phase,under saturation depth,immediately after surfacing,and 24 h later.Results Under pressure,except FVC,all the other indexes were negatively correlated with depth.FEV 1.0 and FEV 1% decreased significantly at 150 m saturation depth,compared with the basic value( P 0 05 and P 0 01).Compared with the base value,MMF tested at the compressing 70 m stop,110 m stop and the 150 m saturation depth was significant decreased( P 0 05, P 0 01 and P 0 01).PEFR at 110 m and at 150 m saturation stages was significantly lower than that at base( P 0 01,0 01)and that at 30 m( P 0 05, P 0 01);During 150 m saturation stage,FEF 25% was significantly decreased,compared with that at base and 30 m( P 0 01,0 05);FEF 50% was significantly decreased,compared with that at base,30 m,70 m and 110 m( P 0 01,0 05,0 05,0 05);FEF 75% was significantly decreased,compared with that at base,30 m,70 m( P 0 01,0 05,0 05).Compared with the base value,FEF 25% ,FEF 50% and FEF 75% were decreased by 25.51%,42.35%,and 56.84% respectively,which suggested that,under pressure,the lower was the pulmonary volume,the more significant was the decrease of flow.After surfacing,all data were within normal range,but a significant decline was seen in MMF and FEF 50% ( P 0 05).24 h later,FEF 25% was restored.Conclusions Dynamic pulmonary functions are mainly affected by the high density gas,and presents small airway dysfunction.But these effects are functional and reversible.The manipulation of the experimental conditions in this saturation diving is safe and successful.