Abstract
One of the possible risks incurred while diving is inert gas narcosis (IGN), yet its mechanism of action remains a matter of controversy. Although providing insights in the basic mechanisms of IGN, research has been primarily limited to animal studies. A human study, in real diving conditions, was needed. Twenty volunteers within strict biometrical criteria (male, age 30-40years, BMI 20-23, non smoker) were selected. They performed a no-decompression dive to a depth of 33mfw for 20min and were assessed by the means of critical flicker fusion frequency (CFFF) measurement before the dive, during the dive upon arriving at the bottom, 5min before the ascent, and 30min after surfacing. After this late measurement, divers breathed oxygen for 15min and were assessed a final time. Compared to the pre-dive value the mean value of each measurement was significantly different (p<0.001). An increase of CFFF to 104±5.1% upon arriving to the bottom is followed by a decrease to 93.5±4.3%. This impairment of CFFF persisted 30min after surfacing, still decreased to 96.3±8.2% compared to pre-dive CFFF. Post-dive measures made after 15min of oxygen were not different from control (without nitrogen supersaturation), 124.4±10.8 versus 124.2±3.9%. This simple study suggests that IGN (at least partially) depends on gas-protein interactions and that the cerebral impairment persists for at least 30min after surfacing. This could be an important consideration in situations where precise and accurate judgment or actions are essential.
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