Int J Sports Med 2016; 37(14): 1124-1128
DOI: 10.1055/s-0042-110573
Physiology & Biochemistry
© Georg Thieme Verlag KG Stuttgart · New York

Do Environmental Conditions Contribute to Narcosis Onset and Symptom Severity?

P. Lafère
1   Anaesthesia & Reanimation, Hopital de la Cavale-Blanche, Brest, France
C. Balestra
2   Environmental & Occupational Physiology, Haute Ecole Paul Henri Spaak, Auderghem, Belgium
W. Hemelryck
3   Haute Ecole Paul henri spaak, Research Laboratory, Brussels, Belgium
F. Guerrero
4   Université de Bretagne Occidentale, EA4324 – ORPHY, Brest, France
P. Germonpré
5   Military Hospital “Queen Astrid”, Centre for Hyperbaric Oxygen Therapy, Brussels, Belgium
› Author Affiliations
Further Information

Publication History

accepted after revision 03 June 2016

Publication Date:
13 October 2016 (online)


Although many factors contributing to inert gas narcosis onset and severity have been put forward, the available evidence is not particularly strong. Using objective criteria, we have assessed brain impairment associated with narcosis under various environmental diving conditions. 40 volunteers performed a no-decompression dive (33 m for 20 min) either in a dry chamber, a pool or open sea. They were assessed by critical flicker fusion frequency before the dive, upon arriving at depth, 5 min before ascent, on surfacing and 30 min post-dive. Compared to the pre-dive value, the mean value of each measurement was significantly different. An increase of flicker fusion to 105.00±0.69% when arriving at depth is followed by a decrease to 94.05±0.65%. This impairment persists when surfacing and 30 min post-dive, decreasing further to 96.36±0.73% and 96.24±0.73%, respectively. Intragroup comparison failed to demonstrate any statistical difference. When objectively measured narcosis may not be influenced by external factors other than pressure and gas. This might be of importance for training to avoid any over- or underestimation of the severity of narcosis based only on subjective symptoms.