Laryngeal mask airway severed by biting

Abstract

EDITOR: Complications with both reinforced laryngeal mask airways and reinforced endotracheal tubes relate to compression of the lumen [1-3]. We describe what we believe is the first report of severance of a non-reinforced laryngeal mask airway during emergence from general anaesthesia. A 27-yr-old male weighing 85 kg presented for elective knee arthroscopy. He was fit and well with no previous history of anaesthesia. He smoked 10 cigarettes per day and consumed an average of 10 units of alcohol per week. General anaesthesia was induced with fentanyl and propofol, a size 4 laryngeal mask airway was inserted easily and the patient spontaneously breathed nitrous oxide and sevoflurane in oxygen through a closed circle breathing system. Intraoperatively, he was given intravenous cyclimorph 6 mg for analgesia and ondansetron 4 mg to minimize postoperative nausea and vomiting. Surgery and anaesthesia were uneventful until emergence when the patient was positioned on his left side still breathing through the laryngeal mask airway. The patient raised his right hand to remove his laryngeal mask airway and at the same time he bit down hard and completely severed the airway (Fig. 1). He was not sufficiently lucid to open his mouth to command, which would have allowed us to retrieve the retained portion of the mask from his oropharynx, and he became hypoxic (SPO2 77%). Fortunately, at this moment, he opened his mouth slightly and the retained portion of the mask was removed using a Magill intubating forceps. Oxygen saturation quickly returned to 100%. His teeth were not damaged in any way. The remainder of his recovery period was uneventful and the patient was discharged home later that day.Figure 1: Laryngeal mask severed in half. The cuffed portion was momentarily unretrievable from the patient's mouth.This incident raises a number of important issues. In a previously reported case of problems associated with the reinforced laryngeal mask airway - because the sterilization record could not be found - concern was expressed that the recommended number of 40 usages had been exceeded [2]. However, the sterilization record for the reinforced laryngeal mask airway used indicated that it had only been used 16 times and was therefore well within its recommended shelf life. Furthermore, it has been recommended that bite blocks be used with all laryngeal mask airways on emergence from anaesthesia [4]. This is not standard practice in our institution because we are concerned of the potential trauma to lips and teeth in spontaneously breathing patients. However, Brimacombe and colleagues recommended that suitable bite blocks be prepared by rolling gauze swabs into a cylindrical shape and securing them tightly with adhesive tape to a thickness of 2.5 cm [4]. The Guedel airway has been shown not to be a suitable alternative to a bite block [5]. Finally, the issue of the sensible time to remove the laryngeal mask airway after the end of anaesthesia is undetermined [6,7]. Further work may find an answer to the question whether the laryngeal mask airway should be removed when patients are either deeply anaesthetized or wide awake. The solution may help avoid the occurrence of this rare but potentially serious problem. A. M. Heffernan M. White A. Curran S. A. Colbert The Adelaide and Meath Hospital, Tallaght; Dublin, Ireland