Ear injury caused by elevated intratympanic pressure during general anaesthesia

Two cases of middle-ear injury, due to sharp fluctuations of intratympanic pressure as a result of general anaesthesia with nitrous oxide are presented. A study is reported indicating that the degree of these fluctuations is a function of the concentration of nitrous oxide. In order to reduce the risk of middle-ear injury due to nitrous oxide anaesthesia, it is suggested that the lowest concentration feasible should be used where there is a history of previous ear surgery.