FURTHER WORK ON THE DEPRESSION OF LARYNGEAL REFLEXES DURING KETAMINE ANAESTHESIA USING A STANDARD CHALLENGE TECHNIQUE

The requirements for a standardized method of assessment of laryngeal reflexes are discussed. A suitable technique is described and was used in seventeen patients to investigate the factors influencing the depression of laryngeal reflexes during ketamine anaesthesia. Inhalation of contrast medium was found during ketamine anaesthesia following premedication with both hyoscine and atropine. Aspiration was not found to be related to the depth of anaesthesia. However, a progressive depression of laryngeal reflexes was demonstrated as the duration of anaesthesia and total dose of ketamine increased. It is suggested that the use of different techniques of laryngeal challenge by various workers is the major reason for conflicting results in this area of investigation.