Flow resistance of endotracheal tubes under laser exposure

For laser safety it is absolutely necessary that endotracheal tubes do not ignite under exposure of laser radiation. Furthermore these tubes should remain in working condition. A critical point was observed in the conduits which are used to expand the cuffs at the distal end of the tube. In some constructions these conduits are guided in the inner lumen of the tube. It was seen experimentally that laser exposure can destroy the conduits which leads to a narrowing of the gas flow through the tube. The gas flow resistance inside of different tubes was measured while the tubes were exposed by carbon-dioxide laser radiation. Caused by the specific constructions and the physical properties of the materials, the flow resistance of some tubes changed, while it was constant in other tubes. These experimental results were compared with results observed during the clinical use of different tubes.