• Mumin Hakim, Senthil G Krishna, Ahsan Syed, Meredith Lind, Charles Elmaraghy, and Joseph D Tobias.
• Department of Anesthesiology & Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.
• Paediatr Anaesth. 2016 Jan 1; 26 (1): 72-6.

BackgroundThe laryngeal mask airway is increasingly used as an airway adjunct during general anesthesia. Although placement is generally simpler than an endotracheal tube, complete sealing of the airway may not occur, resulting in contamination of the oropharynx with anesthetic gases. Oropharyngeal oxygen enrichment may be one of the contributing factors predisposing to an airway fire during adenotonsillectomy. The current study prospectively assesses the oropharyngeal oxygen and volatile anesthetic agent concentration during laryngeal mask airway use in infants and children.MethodsFollowing the induction of general anesthesia and placement of a laryngeal mask airway, the oropharyngeal gas sample was obtained by placing a 14-gauge catheter attached to the gas sampling tube into the oropharynx above the laryngeal mask airway. The oropharyngeal concentration of the oxygen and the anesthetic agent were recorded for five breaths during both spontaneous ventilation (SV) and positive pressure ventilation (PPV).ResultsThe study included 238 patients. The oropharyngeal concentration of sevoflurane was >50% of the inspired sevoflurane concentration during SV in 10 of 238 (4.2%) patients and during PPV in 135 of 238 (56.7%) patients. Similarly, during SV and PPV, the oropharyngeal oxygen concentration was >21% in 30 of 238 (12.6%) patients and in 188 of 238 (79%) patients, respectively. Significantly, we also noticed that the oropharyngeal oxygen concentration exceeded 50% in 5 of 238 (2.1%) patients during SV and in 139 of 238 patients (58.4%) patients during PPV.ConclusionsWith the use of a laryngeal mask airway and the administration of 100% oxygen, there was significant contamination of the oropharynx during both PPV and SV. The oropharyngeal concentration of oxygen was high enough to support combustion in a significant number of patients. The use of a laryngeal mask airway does not ensure sealing of the airway and may be one risk factor for an airway fire during adenotonsillectomy.© 2015 John Wiley & Sons Ltd.

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