Awareness during general anaesthesia for bronchoscopy and laryngoscopy using the apnoeic oxygenation technique.

Two hundred patients were interviewed before and after elective bronchoscopy or laryngoscopy. Premedication consisted of pethidine together with either atropine or hyoscine. Anaesthetic drugs were restricted to thiopentone and suxamethonium. Eight patients (4%) described some degree of awareness. No statistically significant correlation with awareness was demonstrated for the premedication, the sex, or the weight of the patients, but awareness was more common in the younger age group. Awareness could not be related to the size of the induction dose of thiopentone, the use of a "single shot" technique, or the use of incremental injections, duration of anaesthesia, dosage calculated in mg/kg/min, the use or not of local anaesthetic spray, or the status of the anaesthetist. Awareness during the apnoeic oxygenation technique is only a particular instance of the general problem of awareness during anaesthesia. Probably the most significant hazard is overhearing conversation. Whenever possible comments during the procedure about pathology and prognosis should be avoided.