Associations between psychological factors and pulmonary toxicity during intermittent oxygen breathing at 2 ATA

Associations between the psychological and pulmonary effects of breathing intermittent oxygen at 2 ATA were examined among four experienced divers. A fifth diver, who served as a control, breathed only normoxic nitrogen. Psychological tests included digit span, short-term memory for easy and difficult word associations, simple and complex psychomotor performance, and reported moods. The criterion of oxygen toxicity was the total hours of intermittent oxygen exposure tolerated before developing a 10% reduction in vital capacity. Short-term memory for difficult word associations and self-reported moods of Activity, Depression, Fatigue, and Happiness were found to be significantly correlated with this criterion of oxygen toxicity. Part of the impairment found on these measures, however, was probably related to the absence of adequate sleep and rest as evidenced by the worsened performance of the control diver over the 15-h testing period. The results replicated the findings of earlier research on the psychological effects of continuous oxygen breathing under hyperbaric conditions and at 1 ATA, and may indicate that oxygen intesifies the effects of other stressors such as fatigue. In addition, the results showed that reported moods may be important indicators of impending pulmonary toxicity during intermittent oxygen exposure.