[Endotracheal tube cuff and nitrous oxide: bench evaluation and assessment of clinical practice]

To evaluate the risk of over-inflation of endotracheal tube cuffs (ETC) when used with nitrous oxide (N(2)O); to assess the rate of under and over-inflation of ETC when they are inflated without a manometer; to survey anesthesiologists about how they prevent these risks.

Nine types of endotracheal tube were studied on bench using various N(2)O concentrations; airway pressure levels and two sizes of trachea. Then, the rate and magnitude of over and under inflation pressure of ETC was assessed in our clinical practice. Finally, a national survey assessed how anesthesiologists prevented misuse of endotracheal tube with N(2)O.

Pressure in ETC rose sharply using N(2)O, up to more than 40 cmH(2)O in six over nine tube types. Only two tube types (Mallinckrodt Hi-Lo Brandt and Lanz) were immune regarding N(2)O. Pratice study showed that ETC over inflation (>30 cmH(2)O) and under inflation (<20 cmH(2)O) was observed in 50 and 31 % of patients, respectively when cuff was inflated without a manometer. In France, a minority of anesthesiologists inflated ETC with a manometer (41 %) because in 61 % of theatres only manometers were available.

There are risks induced by the use of N(2)O with tracheal tubes. This study provides data to sensitize users to these risks.