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


CONCLUSIONS
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.
Møllerløkken
Andreas
A
Baromedical and Environmental Physiology Group, Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU, Trondheim, Norway. andreas.mollerlokken@ntnu.no
Gutvik
Christian
C
Berge
Vegard J
VJ
Jørgensen
Arve
A
Løset
Are
A
Brubakk
Alf O
AO
D000818:Animals; D003664:Decompression / Q000009:adverse effects* / Q000379:methods* / Q000592:standards; D003665:Decompression Sickness / Q000097:blood / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004618:Embolism, Air / Q000097:blood / Q000517:prevention & control*; D005260:Female; D006931:Hyperbaric Oxygenation; D008297:Male; D011651:Pulmonary Artery / Q000503:physiopathology; D011897:Random Allocation; D034421:Sus scrofa