title: Oropharyngeal oxygen and volatile anesthetic agent concentration during the use of laryngeal mask airway in children.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  Following 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).
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  With 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.
authors.affiliation: Department of Anesthesiology & Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.
authors.forename: Mumin
authors.initials: M
authors.lastname: Hakim
authors.affiliation: Department of Anesthesiology & Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Anesthesiology, The Ohio State University, Columbus, OH, USA.
authors.forename: Senthil G
authors.initials: SG
authors.lastname: Krishna
authors.affiliation: Department of Anesthesiology & Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Anesthesiology, The Ohio State University, Columbus, OH, USA.
authors.forename: Ahsan
authors.initials: A
authors.lastname: Syed
authors.affiliation: Department of Otolaryngology and Head & Neck Surgery, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Otolaryngology and Head & Neck Surgery, The Ohio State University, Columbus, OH, USA.
authors.forename: Meredith
authors.initials: M
authors.lastname: Lind
authors.affiliation: Department of Otolaryngology and Head & Neck Surgery, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Otolaryngology and Head & Neck Surgery, The Ohio State University, Columbus, OH, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Elmaraghy
authors.affiliation: Department of Anesthesiology & Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.|Department of Anesthesiology, The Ohio State University, Columbus, OH, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Tobias
mesh_terms: D000233:Adenoidectomy; D000293:Adolescent; D000328:Adult; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D017214:Laryngeal Masks; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage*; D009960:Oropharynx; D010100:Oxygen / Q000008:administration & dosage*; D011446:Prospective Studies; D000077149:Sevoflurane; D014068:Tonsillectomy; D055815:Young Adult
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D010100:Oxygen
keywords: airway fire; laryngeal mask airway; oropharyngeal oxygen concentration