Awareness during bronchoscopy.

The purpose of the study was to assess the incidence of awareness during bronchoscopy and to evaluate the effectiveness of auditory random noise in preventing awareness. All patients were unpremedicated and underwent elective bronchoscopy under thiopentone-suxamethonium anaesthesia. Half the patients received auditory random noise preoperatively. Patients were interviewed postoperatively and the incidence of awareness and dreaming assessed. Eleven patients described awareness, of whom three had received random noise. No relation with awareness could be shown with the age and sex of the patient, nor was awareness related to the dosage of thiopentone. Awareness was associated with a short time interval between removal of the bronchoscope and response to command. Awareness is still an important problem in anaesthesia and the use of random noise stimulation to block auditory input of relevance to the patient merits further investigation.