Venous gas bubble production following cold stress during a no-decompression dive.

The effect of cold stress on venous gas bubble production was studied using Doppler ultrasonic monitoring. Ten subjects participated in four exposure regimes carried out at 78 fsw on an underwater platform for 38 min of light exercise in 10 degrees C water. Two cold exposures (1/8-in. wet suit) and two warm exposures (insulated dry suit) were each followed by rewarming in a heated bath or by endogenous heat production while insulated in a sleeping bag. Results showed that for the cold dives compared to warm dives, air consumption increased 29%, rectal temperature dropped 0.8 degrees C by the end of the dive, mean skin temperature dropped 11 degrees C, and cooling rate correlated with mean skin fold and endomorphy (P less than 0.001). A threefold increase in bubble scores (P less than 0.025) was observed following the warm dives compared to the cold dives. The results suggest that inert gas uptake is reduced as a result of peripheral vasoconstriction when the cold stress is induced at the onset of the dive and maintained throughout.