Laser-resistance of a new jet ventilation catheter (LaserJet®) under simulated clinical conditions [Verhalten des neuen LaserJet®-Katheters bei CO₂-laser- anwendung unter simulierten klinischen bedingungen]

BackgroundLaser surgery within the airway is often performed with the patient under general anaesthesia and with infraglottic jet ventilation via a specially designed catheter which should not be inflammable. We investigated the laser-resistance of a recently introduced jet ventilation catheter (LaserJet®) made of polytetrafluoroethylene.MethodsFor the simulation of gas accumulation in the hypopharynx a cylindric steel chamber with an open and a closed end was used to simulate the operative setting according to the European standard ISO-11990. In a series of 12 tests the disposable laser jet catheter was attached to the proximal end of the oxygen supply tubing, and the distal end was introduced 10 cm into the steel chamber. The catheter was repeatedly exposed to the beam of a CO2-laser device with energies varying from 2–15 W and with an impact angle of 75°. The changes in the catheter were assessed with and without an oxygen flow of 6 l/min. Time of exposure varied from 1 to 10 s. Size and nature of the changes in the catheter were documented.ResultsWe found damage to the catheter that occurred in the following order: simple (front wall) and double perforation (front and back wall), smoke emission as evidence for pyrolysis, discolouration, deformation and rupture. The extent of damage to the catheter shaft under direct laser beam exposition was dependent on the laser intensity. When there was no oxygen flow, a beam of 2 W needed 40 s to perforate the catheter shaft, while with an oxygen flow of 6 l/min, a laser intensity of 4 W needed 20 s to cause perforation. Rupture of the catheter occurred in less than 10 s with a laser intensity of 8 W or more.ConclusionsWe could demonstrate that the LaserJet® catheter is not inflammable and also does not sustain fire. However, it is not laser-resistant as to maintaining its texture and shape while under direct exposure to a continuous laser beam, as applied under clinical conditions. Polytetrafluoroethylene deforms and melts at temperatures above 327°C which is usually exceeded by the CO2-laser.