[Respiratory tract obstruction caused by ballooning of an intubation tube cuff during nitrous oxide inhalation].

A typical case of upper airway obstruction due to deformation of a low pressure tracheal tube cuff is reported. It would seem that this herniation may have been due to nitrous oxide diffusing with in the air-filled cuff, thereby causing it to overdistend. This increase in pressure occurred after 3 hours of inhalation of a mixture of oxygen and nitrous oxide. The deformed cuff may either block the lumen at the end of the tube, or push the tube against the tracheal wall. The result is, in either case, a mechanical obstruction of the airway, with hypoxia, and then anoxia. In the reported case, it was the decrease of SpO2 which alerted the anaesthetist. Pulse oximetry was helpful for an early diagnosis. To avoid such accidents, it is suggested either to inflate the cuff with the gas mixture with which the patient is ventilated, or to deflate it every 30 min.