A TEST FOR VARIATIONS IN INDIVIDUAL SENSITIVITY TO HYPERBARIC-OXYGEN TOXICITY

It has been suggested that some individuals have above-average sensiti vity to hyperbaric oxygen toxicity. An extensive human study completed at the Naval Experimental Diving Unit (NEDU) tested human tolerance t o HBO and raised the possibility of assessing this hypothesis. In a gr oup of 113 subjects given multiple exposures, some developed no sympto ms of O-2 toxicity while others developed symptoms on several occasion s. The subjects in this study received unequal numbers of exposures of different depths and durations however, and it was not obvious how to determine unusual sensitivity. To assess the influences of chance vs. differences in sensitivity on the outcome of this experimental series , we performed a Monte Carlo simulation in which the experimental desi gn was duplicated and the sensitivity hypothesis was evaluated statist ically. The number of subjects giving rise to any symptoms and the dis tribution of individuals having symptoms on multiple occasions were ev aluated. The simulation showed that the NEDU results were not unusual: nearly one quarter of the time the observed pattern of multiple sympt oms could have been expected due to chance alone. The power of this si mulation would have permitted detection of sensitivity factors 10 time s (or greater) normal in 20% of the subjects at least half of the time .