Recompression during decompression and effects on bubble formation in the pig.

Abstract

INTRODUCTION: There is a relationship between gas bubble formation in the vascular system and serious decompression sickness. Hence, control of the formation of vascular bubbles should allow safer decompression procedures. METHODS: There were 12 pigs that were randomly divided into an experimental group (EXP) and a control group (CTR) of 6 animals each. The pigs were compressed to 500 kPa (5 ATA) in a dry hyperbaric chamber and held for 90 min bottom time breathing air. CTR animals were decompressed according to a modified USN dive profile requiring four stops. EXP followed the same profile except that a 5-min recompression of 50 kPa (0.5 ATA) was added at the end of each of the last three decompression stops before ascending to the next stop depth. RESULTS: All CTR animals developed bubbles, compared with only one animal in EXP. The number of bubbles detected during and after the dive was 0.02 +/- 0.02 bubbles x cm(-2) in CTR, while the number of bubbles detected in EXP were 0.0009 +/- 0.005 bubbles x cm(-2); the difference was highly significant. CONCLUSION: By brief recompression during late decompression stops, the amount of bubbles was reduced. Our findings give further support for a gas phase model of decompression.