Nitrogen Narcosis, the High Pressure Nervous Syndrome and Trimix.

Abstract

All mammals, including man, exposed to increasing pressure of breathing gas mixture show disturbances at the level of the nervous system, which differ according to which gas is used. Compressed air or nitrogen-oxygen mixture produces from 3 bars, nitrogen narcosis (Bennett and Rostain 2003a). When nitrogen is replaced by a gas less narcotic such as helium, at pressures exceeding 18 bars the breathing mixture induces the high pressure nervous syndrome (HPNS) (Rostain 1993; Bennett and Rostain 2003b).