Hemoglobin desaturation after succinylcholine-induced apnea - A study of the recovery of spontaneous ventilation in healthy volunteers

Background: Because of the rapid recovery of neuromuscular function after succinylcholine administration, there is a belief that patients will start breathing sufficiently rapidly to prevent significant oxygen desaturation. The authors tested whether this belief was valid. Methods: Twelve healthy volunteers aged 18-45 yr participated in the study. After preoxygenation to an end-tidal oxygen concentration greater than 90%, each subject received 5 mg/kg thiopental and 1 mg/kg succinylcholine. Oxygen saturation (Sao(2)) was measured at both a finger and an ear lobe (beat to beat). During the period of apnea and as they were recovering, the volunteers received continuous verbal reassurance by the investigators. If the Sao(2) decreased below 80%, the volunteers received chin lift and, if necessary, assisted ventilation. The length of time the subject was apneic and level of desaturation were related by linear regression analysis. One hour after recovery and again 1 week later, subjects were asked a series of questions regarding their emotional experience. Results: In six volunteers, Sao(2) decreased below 95% during apnea; in four, Sao(2) decreased below 80%, necessitating chin lift and assisted ventilation in three. Apnea time was significantly longer in volunteers who reached Sao(2) less than 80% than in those who did not (7.0 +/- 0.4 and 4.1 +/- 0.3 min, respectively), and there was a significant correlation between the length of time the subject was apneic and the magnitude of desaturation. Conclusions: Spontaneous recovery from succinylcholine-induced apnea may not occur sufficiently quickly to prevent hemoglobin desaturation in subjects whose ventilation is not assisted.