ABSTRACT
To investigate the effect of hyperoxia on EKG findings and to evaluate the applicability of EKG as noninvasive monitoring index of oxygen toxicity, 38 rabbits were continuously exposed to 6 different conditions-3 hyperbaric oxygenations (HBO-2.5, 3.5 and 5ATA, 100% O2), normobaric oxygenation (NBO, 100% O2), hyperbaric aeration (HBA-5ATA, 21% O2) and normobaric aeration (NBA, 21% O2)-for 120 minutes and their EKG and time to dyspnea and convulsion were recorded. Dyspnea and death were observed in exposure conditions of HBO-3.5 and HBO-5 (Positive rate of dyspnea; 10%, 100%, death; 10%, 25%, respectively) only, and convulsion in 4 oxygenation groups (NBO; 20%, HBO-2.5; 20%, HBO-3.5; 20%, HBO-5; 88%). Abnormal EKG findings included arrhythmia and ST-T changes and the incidences was increasing with doses(partial pressure of oxygen). In addition to EKG change, findings observed during exosure were dyspnea and convulsion in the order of appearence and when non specific ST-T change was accepted as positive (abnormal) finding, the frequency of abnormal EKG was statistically significant(p0.05). These results suggest that the effect of hyperoxia on heart is myocardial ischemia and arrhythmia, that oxygenation more than 3.5ATA causes myocardial damage in 120 minutes exposure, and that EKG is valuable as monitoring index of oxygen toxicity.