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

Abstract

Objective: 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.

Methods: 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.

Results: 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.

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