Middle ear pressure variations during nitrous oxide and oxygen anaesthesia.

Many authors have reported middle ear pressure variations during inhalation of high concentrations of nitrous oxide. An on-going study on subjects anaesthetized with nitrous oxide and oxygen supplemented with halogens or narcotics and excluding operations on the ear enables us to register three typical curves of middle ear pressure according to the patency of the Eustachian tube. We recorded significant negative middle ear pressures during the recovery period when there was important obstruction of the Eustachian tube.