The effect of blood on laser-resistant endotracheal tube combustion

The protection afforded against CO2 laser-induced combustion by five different types of tracheal tubes or protective foil wraps was evaluated. They were compared before and after the application of human blood to their external surfaces. The tracheal tubes tested were polyvinylchloride (PVC) tubes wrapped with Venture copper (Cu) foil tape, 3M aluminum (Al) foil tape, and the Laser-Guard protective coating. The Xomed Laser Shield II and Mallinckrodt Laser-Flex tracheal tubes were also tested. A CO2 laser set to 38 W in the continuous mode was directed at the shaft of the tracheal tube under study, which had 5 L/min of oxygen flowing through it. The laser was actuated for 90 seconds or until combustion or melting occurred. The copper foil-wrapped and aluminum foil-wrapped PVC tracheal tubes were unaffected by 90 seconds of laser fire in five trials with each type of tape. However, the application of blood to the foil wrapped PVC tracheal tube shafts resulted in combustion in 3 of 5 copper foil-wrapped tubes and melting of the underlying tracheal tube shaft in 3 of 5 aluminum foil-wrapped PVC tracheal tubes. Blood did not affect the protection afforded by the Laser-Guard coating when it was applied to the shafts of PVC tracheal tubes. Similarly, the Xomed Laser Shield II tracheal tube's shaft offered good protection from the laser both before and after application of blood. Combustion occurred in 1 of 4 Mallinckrodt Laser Flex tracheal tubes studied prior to the application of blood. The application of blood resulted in almost immediate combustion in all 4 Mallinckrodt Laser Flex tracheal tubes tested. The presence of blood on the surface of metallic foil-wrapped or special tracheal tubes may make laser-induced combustion more likely during airway surgery. However, the Laser-Guard protective coating and the Xomed Laser-Shield II tracheal tube provide good protection even when covered with blood.