Decompression sickness in the rat following a dive on trimix: recompression therapy with oxygen vs. heliox and oxygen

• Published in: Journal of applied physiology (1985) 2007-04, Vol.102 (4), p.1324-1328
• Main Authors: Arieli, R, Svidovsky, P, Abramovich, A
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Comparative analysis; Computer Simulation; Decompression Sickness - etiology; Decompression Sickness - physiopathology; Decompression Sickness - therapy; Disease Models, Animal; Diving; Diving - adverse effects; Drug Combinations; Fundamental and applied biological sciences. Psychology; Helium; Helium - administration & dosage; Hyperbaric Oxygenation - methods; Male; Medical treatment; Models, Biological; Nitrogen; Nitrogen - administration & dosage; Oxygen - administration & dosage; Oxygen therapy; Rats; Rats, Sprague-Dawley; Treatment Outcome
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01195.2006

Israel Naval Medical Institute, Israel Defense Forces Medical Corps, Haifa, Israel Submitted 22 October 2006 ; accepted in final form 18 December 2006 Trimix (a mixture of helium, nitrogen, and oxygen) has been used in deep diving to reduce the risk of high-pressure nervous syndrome during compression and the time required for decompression at the end of the dive. There is no specific recompression treatment for decompression sickness (DCS) resulting from trimix diving. Our purpose was to validate a rat model of DCS on decompression from a trimix dive and to compare recompression treatment with oxygen and heliox (helium-oxygen). Rats were exposed to trimix in a hyperbaric chamber and tested for DCS while walking in a rotating wheel. We first established the experimental model, and then studied the effect of hyperbaric treatment on DCS: either hyperbaric oxygen (HBO) (1 h, 280 kPa oxygen) or heliox-HBO (0.5 h, 405 kPa heliox 50%-50% followed by 0.5 h, 280 kPa oxygen). Exposure to trimix was conducted at 1,110 kPa for 30 min, with a decompression rate of 100 kPa/min. Death and most DCS symptoms occurred during the 30-min period of walking. In contrast to humans, no permanent disability was found in the rats. Rats with a body mass of 100–150 g suffered no DCS. The risk of DCS in rats weighing 200–350 g increased linearly with body mass. Twenty-four hours after decompression, death rate was 40% in the control animals and zero in those treated immediately with HBO. When treatment was delayed by 5 min, death rate was 25 and 20% with HBO and heliox, respectively. technical diving; helium; hyperbaric chamber Address for reprint requests and other correspondence: R. Arieli, Israel Naval Medical Institute, POB 8040, Haifa 31080, Israel (e-mail: rarieli{at}netvision.net.il )