Large Air Leak from an Endotracheal Tube due to a Manufacturing Defect

Abstract

To the Editor: We report an unusual cause of an air leak from an endotracheal tube (ETT) after intubation. A 40-yr-old woman presented for removal of a cyst from her knee. After induction of anesthesia with propofol, vecuronium, and fentanyl, ventilation via a bag and mask was accomplished with no difficulty. She was tracheally intubated with an 8-mm external diameter Portex[registered sign] blue-line endotracheal tube. The cuff was initially inflated, and then a large gas leak was detected on bag ventilation despite further air being injected incrementally into the cuff to a total volume of 18 mL. The pilot balloon appeared firmly inflated. The ETT had not yet been tied in place, and no obvious obstruction to the pilot or inflation tube was detected. The anesthetic circuit was disconnected from the ETT and a quick pressure test of this circuit revealed no significant gas leak. There was no audible gas leak, but on close inspection of the ETT, a flow of gas was felt close to the attachment of the pilot tube. The ETT was changed, and the surgical procedure was completed with no further difficulty. An elliptical defect in the wall of the ETT was noted, which was at the level of the notch cut for the insertion of the pilot tube (Figure 1). It appeared in this case that the notch had been cut too deep, resulting in a defect in the wall of the tube. In correspondence with Portex Limited (Smiths Industries Medical Systems), this was confirmed and thought to be related to the sharpness of the manufacturing blade and the regularity with which they are changed (Smiths Industries Medical Systems, personal communication, July 23, 1996). No other reports of this particular defect have been published.Figure 1: An elliptical defect in the wall of the endotracheal tube.A published analysis of ETT leakage has revealed that malposition is the most likely cause of ETT leakage, but when mechanical defects were present, these were most likely to involve the cuff or pilot valve [1]. A recent report of a slow leak at the site of the insertion of the pilot tube into the wall of the ETT has been published [2]. We conclude that in this case, routine preinduction checking of the ETT failed to reveal any defect. The idiom of "if in doubt, take it out" may still be of most benefit when facing such a situation. B. M. F. Lewer Z. Karim R. S. Henderson Section of Anaesthesia; Wellington School of Medicine; Wellington, New Zealand