title: Monitoring pollution by proton-transfer-reaction mass spectrometry during paediatric anaesthesia with positive pressure ventilation via the laryngeal mask airway or uncuffed tracheal tube.
abstract: Twenty children aged 2-66 months were randomly allocated for airway management with either the laryngeal mask airway or uncuffed tracheal tube using intermittent positive pressure ventilation with a tidal volume of 8 ml.kg-1 and a respiratory rate adjusted to maintain end-expiratory carbon dioxide concentration at 5.3 kPa. Induction was with fentanyl/propofol and maintenance was with sevoflurane 2.5% in oxygen/air. The airway device was removed when the patients were awake and the patients were transferred to the postanaesthesia care unit 10 min later. Air was sampled from a point 1.5 m above the floor at a location remote from the ventilation outlet and analysed using a proton-transfer-reaction mass spectrometer capable of continuous trace gas analysis at the parts per billion volume (ppbv) level. The concentration of sevoflurane was recorded every minute during three consecutive phases: for 5 min before the introduction of sevoflurane (background); after introduction of sevoflurane until removal of the airway device (intra-operative); and every minute after removal until the concentration returned to background levels. Median (interquartile range [range]) intra-operative sevoflurane concentrations were 200-400 times higher than background values for the laryngeal mask airway 1 (1-2 [0-3]) ppbv vs. 404 (278-523 [83-983]) ppbv, respectively, and the tracheal tube 2 (1-3 [0-5]) ppbv vs. 396 (204-589 [107-1735]) ppbv (both p < 0.0001), and returned to background values within 5 min of removal. There were no differences in sevoflurane concentration between devices intra-operatively or after removal. The performance of the proton-transfer-reaction mass spectrometer was identical at the start and end of the 30-day study. We conclude that peri-operative sevoflurane concentration in a modern operating theatre is similar for the laryngeal mask airway and the uncuffed tracheal tube in paediatric patients receiving intermittent positive pressure ventilation. Intra-operative sevoflurane concentrations are five times lower than occupational safety limit requirements, and 1000 times lower 5 min after removal of the airway device with the patient awake. The proton-transfer-reaction mass spectrometer has potential for monitoring air quality in the operating theatre.
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Leopold-Franzens University, Innsbruck 6020, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Rieder
authors.forename: C
authors.initials: C
authors.lastname: Keller
authors.forename: J
authors.initials: J
authors.lastname: Brimacombe
authors.forename: G
authors.initials: G
authors.lastname: Gruber
authors.forename: P
authors.initials: P
authors.lastname: Lirk
authors.forename: G
authors.initials: G
authors.lastname: Summer
authors.forename: A
authors.initials: A
authors.lastname: Amann
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000032:analysis; D002675:Child, Preschool; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal / Q000379:methods*; D017214:Laryngeal Masks; D013058:Mass Spectrometry / Q000379:methods; D008738:Methyl Ethers / Q000032:analysis; D009873:Operating Rooms; D011175:Positive-Pressure Respiration; D000077149:Sevoflurane
chemical_list: D000395:Air Pollutants, Occupational; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane