THE INCENDIARY CHARACTERISTICS OF THE LARYNGEAL AND REINFORCED LARYNGEAL MASK AIRWAY TO CO2-LASER STRIKE - A COMPARISON WITH 2 POLYVINYL-CHLORIDE TRACHEAL TUBES

The incendiary characteristics of the laryngeal and reinforced laryngeal mask airway to the CO2 laser have been compared with two polyvinyl chloride tracheal tubes. Three different power densities (2.35, 4.7 and 9.8 x 10(3) watt/cm(2)) were used, with either oxygen or a 30% oxygen/70% nitrous oxide mixture flowing down the tube. The laryngeal mask airway (and reinforced model) was shown to be more resistant than the polyvinyl chloride tracheal tubes. The laryngeal mask tube could not be ignited at a power density of 2.25 x 10(3) watt/cm(2) after five minutes, although penetration occurred in 20-30 seconds. A layer of silica ash built up at the impact site and protected the underlying tube. The laryngeal mask airway cuff was penetrated at 3 to 5 seconds. At this power density the polyvinyl chloride tube ignited in 2 to 8 seconds and the cuff was penetrated in 0.1 seconds. At the highest power density the tubes of all airways ignited within 0.2 seconds. The possibilities for improving the incendiary characteristics of the laryngeal mask airway are discussed.