I read with interest the letter of Dr. Al-Shaikh. As we have emphasized it in our article, filling the cuff with saline was done for the purpose of the study and cannot be recommended in routine clinical practice. 1It is clear that a tube cuff design that prevents increase in the intracuff pressure during N2O anesthesia is of great interest for daily clinical practice. The new design endotracheal tube cuff evaluated by Dr. Al-Shaikh et al. , 2because of a very low permeability to N2O, allowed a very good intracuff pressure stability during N2O anesthesia and seems particularly promising. Nevertheless, we believe that intracuff pressure measurement after cuff inflation is necessary. Indeed, the pressure/volume curve of endotracheal tube cuff has an asymptotic shape and reaches rapidly (for low volume of the cuff) a relative plateau around which very small variations of volume are associated with large increase in cuff pressure. Then, even without N2O diffusion, the cuff pressure can be high because of an inappropriate initial cuff inflation. We recommend, whatever the endotracheal tube device used, at least one cuff pressure control after initial cuff inflation to prevent excessive intracuff pressure and occurrence of tracheal injury.

Combes X, Schauvliege F, Peyrouset O, Motamed C, Kirov K, Dhonneur G, Duvaldestin PI: Intracuff pressure and tracheal morbidity: Influence of filling cuff with saline during nitrous oxide anesthesia. A nesthesiology 2001; 95: 1120–4
Al-Shaikh, Jones M, Baldwin F: Evaluation of pressure changes in a new design tracheal cuff, the Porex Soft Seal, during nitrous oxide anaesthesia. Br J Anaesth 1999; 83: 805–6