Visual Evoked Responses, EEG's and Reaction Time During a Normoxic Saturation Dive, NISAT I.

摘要

One of the major factors limiting man's ability to work at depth is the occurrence of nitrogen narcosis. Other related problems include oxygen toxicity, decompression trauma and carbon dioxide retention. The effects of these three stresses on man's functioning can be investigated using several methods. Two of these methods, one electrophysiological and the other behavioral, have been successfully used to differentiate the effect of nitrogen narcosis and the effect of pressure per se. NISAT I was designed to assess the effect of an extended dive on functioning. In this dive Navy divers were exposed to approximately 200FSW for seven consecutive day. The breathing mixture contained oxygen levels comparable to those of normal air. This paper presents the results of the electrophysiological recordings (both electroencephalograms and visual evoked potentials) made during this dive and the results of a combined electrophysiological/reaction time measure. Decrements were found in the brain's response to repetitively presented light flashes. Similar changes are typically found in short term dives to the same depth. The variability of the response to fast flash rates and the speed of the response to slow flash rates also increased during the dive. The results are discussed as reflecting the operation of at least two different effects, one a deficit in the ability to process incoming sensory information, and the second a more general brain dysfunction.