Nd-YAG laser ignition of silicone endobronchial stents

Study objectives: To test the incendiary characteristics of various silicon e endobronchial stents under the impact of the Nd-YAG laser. Design: In vitro study in the laser laboratory of a university-affiliate ci ty hospital. Setting: The experiments were performed in a reaction chamber under control led oxygen concentrations. The radiolucent and radiopaque Dumon silicone st ent (Novatech; Aubagne, France) and the tracheal part of the Dynamic stent (Ruesch AG; Kernen, Germany) were tested. The Dumon stents were either clea n, covered with a thin layer of blood, or mounted on fresh pig tracheal wal l. The laser was aimed on them perpendicularly from distances of 1.0 cm and 0.5 cm, Interventions: Minimal oxygen concentration to allow ignition and impact ti me for power outputs (POs) between 10 W and 80 W were determined. Measurements and results: The lowest oxygen concentration that allowed igni tion of some stents was 40%. The clean radiolucent stent could not be ignit ed with up to 100% ambient oxygen concentration, Radiopacity, presence of b lood, tracheal wall, and metal, as well as higher PO and shorter distance o f the laser probe decreased impact time to ignition. The radiopaque blood-c overed stent was most easily ignited, For this stent, at a PO of 40 W, impa ct time to ignition was 1.5 +/- 0.2 s, and at 30 W was 2.6 +/- 0.3 s, Conclusions: At ambient oxygen concentrations greater than or equal to 40%, silicone stents can catch fire. Depending on the condition of the stent, t he distance of the laser probe, and PO, ignition can occur after short impa ct times, To prevent stent ignition, oxygen concentration should be kept < 40%, When unusual circumstances require working with higher oxygen concentr ations, pulse duration needs to be limited or stent removal might be consid ered before firing the laser.