Measurements were made in the laboratory of the changes with time of the intracuff pressure, the leak-past pressure (the airway pressure at which gas begins to leak past the cuff) and the cuff volume for 9.5-mm tracheal tubes: red rubber, latex (both Leyland Medical) and p.v.c. (Portex Blue Line). The cuffs were influated with air and exposed to air or air with enflurane or halothane, usually for 90 min. Measurements of leak-past pressure with these tubes were also made for 75 min in patients whose lungs were ventilated with air and enflurane or air and halothane. The following conclusions can be drawn. Enflurane and halothane had little effect. The intracuff pressure always decreased, but the cuff material crept under the continuous stress, so that cuff volume changed little. The leak-past pressure actually increased over at least 75 min with the p.v.c. tubes, but decreased consistently with the red rubber and latex tubes.
展开▼
