Wednesday April 9, 2008
Case Report - Endotracheal tube manufacturing defect: undetected by routine checking

Dr.Prasant Kumar Kabi, MD (Anaesthesiology)
Consultant Anaesthesiologist,
TATA MOTORS HOSPITAL,
JAMSHEDPUR, JHARKHAND, INDIA.
pkabi@tatamotors.com


Background: Routine inspection and checking of endotracheal tubes prior to use may fail to detect certain manufacturing defects. Here is a case of endotracheal tube leak at the junction where the inflation tube for the pilot balloon is attached to the endotracheal tube. This case report emphasize the importance of maintaining awareness that airway obstruction or leak due to structural defects can still occur even with high quality, prepacked single use plastic endotracheal tubes.

Case: A 36-year-old lady was scheduled for elective Laparoscopic Cholecystectomy. She had a history of rheumatoid arthritis with restricted neck extension. Her other airway parameters were normal. In the operating room she was preoxygenated and induced with Thiopentone Sodium and Suxamethonium . The laryngoscopic view was grade 3 and a bougie was used to facilitate intubation. An 7.0 size Portex endotracheal tube ( Fig.1)was used after routine preoperative endotracheal tube check. She was then connected to the Drager Fabius Anaesthesia machine with ventilator for the maintenance with 66 % N2O , 33 % O2 , Isofluorane and Vecuronium Bromide and the surgery started. Within few minutes of commencing positive pressure ventilation , there was the alarm for airway pressure leak , though there was no appreciable air leak from the mouth as evident by bubbling or leaking noise. The position of the tube was confirmed by equal air entry on both chest and mark at the lip level. At this stage the pilot balloon was noted to have deflated partially. The pilot balloon was inflated with 2 mls of air. After 5 minutes, the leak appeared again and the pilot balloon was again noted to have deflated. I suspected damage to the cuff and decided to replace the endotracheal tube. I then passed a bougie and railroaded a new endotracheal tube. I did not encounter any problem after that and proceeded with the surgery. On examination of the endotracheal tube, I could not find any obvious defect in the cuff or in the pilot balloon. I inflated the cuff with air, which remained patent for 5 minutes, but then started to deflate slowly. I then placed the endotracheal tube inside a water bowl and inflated the cuff (2). To my surprise, there was a leak at the junction where the inflation tube for the pilot balloon is attached to the endotracheal tube(Fig.2, 3 & 4). Even though the endotracheal tube was inspected and the cuff checked before intubation, I could not identify the leak since the cuff remained patent for few minutes. There are reports of endotracheal tube failure due to various reasons like endotracheal tube cuff failure due to valve damage (1), endotracheal tube kinking at the junction where the inflation tube for the pilot balloon is attached to the endotracheal tube (2), the problem we had was an unusual one. I would like to suggest that, during the routine checking of the endotracheal tube, the cuff should be left inflated for at least few minutes to rule out any problems like what we encountered particularly when faced with an anticipated difficult intubation.






References:

1) Heusner JE, Viscomi CM. End tracheal tube cuff failure due to valve damage. Anesth Analg. 1991; 72: 270.

2) Chua WL, Ng AS. A defective endotracheal tube, Singapore Med J. 2002; 43: 476-8.

3) Thomas A. Gettelman,Geoffrey N. Morris, Endotracheal tube failure: undetected by routine testing. Anesth Analg. 1995; 81:1313