Combined effect of denucleation and denitrogenation on the risk of decompression sickness in rats

• Published in: Journal of applied physiology (1985) 2009-04, Vol.106 (4), p.1453-1458
• Main Authors: Arieli, R, Boaron, E, Abramovich, A
• Format: Article
• Language: English
• Subjects: Air Pressure; Animals; Atmosphere Exposure Chambers; Biological and medical sciences; Decompression; Decompression Sickness - mortality; Decompression Sickness - physiopathology; Decompression Sickness - therapy; Diving; Diving - physiology; Effects; Fundamental and applied biological sciences. Psychology; Gases - chemistry; Hyperbaric Oxygenation; Male; Mitochondria - metabolism; Nanoparticles; Nitrogen; Nitrogen - therapeutic use; Noble Gases; Oxygen; Rats; Rats, Sprague-Dawley; Rodents; Studies
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.91146.2008

Israel Naval Medical Institute, Israel Defense Force Medical Corps, Haifa, Israel Submitted 24 August 2008 ; accepted in final form 12 February 2009 We previously hypothesized that the number of bubbles emerging on decompression from a dive, and the resultant risk of decompression sickness (DCS), may be reduced by a process whereby effective gas micronuclei that might otherwise have formed bubbles on decompression are shrunk and eliminated. In a procedure defined by us as denucleation, exposure to hyperbaric oxygen (HBO) would result in oxygen replacing the resident gas in the micronuclei, to be subsequently consumed by the mitochondria when the oxygen pressure is reduced. Support for the validity of our hypothesis may be found in our previous studies on the transparent prawn and the reduction of DCS in the rat. In all of these studies, HBO pretreatment was given before supersaturation with inert gas at high pressure. The purpose of the present study was to compare DCS outcome in rats that underwent nitrogen washout (denitrogenation) alone (9 min O 2 at 507 kPa) after exposure to air at high pressure (33 min at 1,266 kPa), and rats treated by both procedures (denitrogenation + denucleation; 8 min of O 2 breathing followed by 5 min air breathing, both at 507 kPa) after high-pressure air exposure. This was done with the same nitrogen load in both groups before the final decompression (a nitrogen pressure of 467 kPa in fatty and 488 kPa in aqueous tissue). Six of 20 rats in the denitrogenation + denucleation group died, compared with 13 in the denitrogenation group ( P < 0.03). Three rats in the denitrogenation + denucleation group suffered mild DCS, recovering completely within 2 h of decompression. The present study indicates an advantage in considering both denitrogenation and denucleation before decompression. This may have practical application before escape from a disabled submarine, when aborting a technical dive, or in the preparation of aviators for high altitude. diving; nitrogen load; gas micronuclei; hyperbaric pressure Address for reprint requests and other correspondence: R. Arieli, Israel Naval Medical Institute, PO Box 8040, 31 080 Haifa, Israel (e-mail: rarieli{at}netvision.net.il )