Abstract:
We studied the effect of nitrous oxide (N2O) diffusion on size 2 LMA cuff inflation in 52 children, 38±21 months of age. LMA cuffs were inflated with air (Group A) or 65% N2O, oxygen and halothane (Group B). Cuffs were inflated in a stepwise manner, achieving a cuff leak pressure of 17±4 cm H2O for all patients. Cuff volume and intracuff pressure increased in Group A (8.5 ± 1.0 ml to 10.8 ± 1.4 ml and 101 ± 36 mmHg to 152±42 mmHg, respectively) and decreased in Group B (8.9±1.0 ml to 6.6±1.5 ml and 90±30mmHg to 53 ±37 mmHg, respectively). Cuff leak pressure did not change significantly in either group. We conclude that cuff inflation with a mixture of N2O/oxygen prevents N2O diffusion into the cuff, avoiding cuff overinflation without compromising LMA function.