[The intracuff pressure changes in N2O gas-barrier cuff made of a special material]

During inhalation anesthesia using N2O, the intracuff pressure has been reported to increase due to diffusion of N2O into the cuff. The excessive intracuff pressure may produce ischemia of the tracheal mucosa. In this study, the changes in the intracuff pressure of endotracheal tube with a cuff made of a material with high N2O gas-barrier properties were compared with those of the normal endotracheal tubes. Forty adult patients (16 males and 24 females) were anesthetized with oxygen 2 l.min-1, N2O 4 l.min-1 and isoflurane under controlled ventilation and they were divided into the following three groups according to the type of the endotracheal tube used: the tube with a standard cuff made by PORTEX Co. Ltd; the tube with a profile cuff (high volume cuff) made by PORTEX Co. Ltd; the tube with gas-barrier cuff made by TERUMO Co. Ltd. The changes of each intracuff pressure were recorded continuously for 180 minutes after cuff inflation. A marked increase of the pressure was observed after inhalation of N2O in standard and profile cuff groups. In gas-barrier cuff group, there was a tendency of increasing cuff pressure without a statistically significant difference. The present study suggests that the use of a cuff with a material of high N2O gas-barrier properties would be effective to prevent increased intracuff pressure by N2O diffusion, and this would be especially useful during long anesthesia and hypotensive anesthesia.