title: Do Environmental Conditions Contribute to Narcosis Onset and Symptom Severity?
abstract: 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.
authors.affiliation: Anaesthesia & Reanimation, Hopital de la Cavale-Blanche, Brest, France.
authors.forename: P
authors.initials: P
authors.lastname: Lafère
authors.affiliation: Environmental & Occupational Physiology, Haute Ecole Paul Henri Spaak, Auderghem, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Balestra
authors.affiliation: Haute Ecole Paul henri spaak, Research Laboratory, Brussels, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Hemelryck
authors.affiliation: Université de Bretagne Occidentale, EA4324 - ORPHY, Brest, France.
authors.forename: F
authors.initials: F
authors.lastname: Guerrero
authors.affiliation: Military Hospital "Queen Astrid", Centre for Hyperbaric Oxygen Therapy, Brussels, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Germonpré
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D003664:Decompression; D004242:Diving; D004777:Environment; D006801:Humans; D007222:Inert Gas Narcosis / Q000503:physiopathology*; D008297:Male