Are laser-resistant endotracheal tubes safe with the new holmium:YAG infrared laser?

Laser-induced ignition of the endotracheal tube is the most morbid event that may occur during laser surgery of the upper respiratory/digestive tract. The efficacy of two new laser-resistant endotracheal tubes, the Laser-Flex stainless steel tube by Mallinckrodt and the Laser-Shield II tube with teflon-aluminium-silicone coating by Xomed-Treace, was studied under exposure to a newly introduced pulsed infrared laser (holmium:YAG, lambda = 2120 nm) in an experimental setting. The time from the onset of exposure until tube perforation was recorded. Laser exposure was continued for up to 180 s unless tube ignition occurred. Temperature during the following 30 s laser application was measured close to the target zones. The irradiance level of the holmium:YAG laser was in the range required for photoablation and plasma formation and led to laser-induced tube ignition in both types of tube. The steel tube showed greater resistance to laser-induced wall damage than the teflon-aluminium silicone tube. The maximum temperature increase following laser exposure was moderate in both tubes; the mean rise of 10 degrees C for the Laser-Shield tube and 23 degrees C for the Mallinckrodt tube correlating with the physical effects of photoablation.