Nd-YAG laser damage to metal and silicone endobronchial stents: delineation of margins of safety using an in vitro experimental model.
OBJECTIVE
To identify margins of safety within which bronchoscopic Nd-YAG laser resection can be performed without damaging indwelling tracheobronchial stents.


METHODS
Experimental in vitro study simulating a patient-care environment.


METHODS
Uncovered and covered metal Wallstent (Schneider; Zurich, Switzerland) and Dumon (Bryan Corporation; Woburn, MA) silicone stents were deployed in the tracheobronchial tree of a ventilated and oxygenated (fraction of inspired oxygen, 40%) heart-lung block of a dead canine. Rigid bronchoscopic Nd-YAG (1,064 nm) laser procedures were performed in order to deliver laser energy using fiber-to-target distances of 10 mm and 20 mm, and noncontact, continuous-mode, 1-s pulses at power settings of 10 W, 30 W, and 40 W. The major outcome measure was laser-induced stent damage, defined as discoloration, ignition, or breakage. This was assessed using six power densities: 75 W/cm(2), 172 W/cm(2), 225 W/cm(2), 300 W/cm(2), 518 W/cm(2), and 690 W/cm(2).


RESULTS
The uncovered Wallstent and the silicone stent remained intact at power densities of 75 W/cm(2) (10 W, 20 mm) and 172 W/cm(2) (10 W, 10 mm), but were damaged at power densities > 225 W/cm(2) (30 W, 20 mm). The covered Wallstent was damaged at all power densities tested.


CONCLUSIONS
Uncovered Wallstent and silicone stents are not damaged when Nd-YAG laser energy is delivered using power densities < or = 72 W/cm(2) (10 W, 10 mm). Covered Wallstents, however, had a high likelihood of ignition at all power densities studied.
Dalupang
J J
JJ
Interventional Pulmonary Services, Pulmonary and Critical Care Medicine Division, University of California, San Diego Medical Center, San Diego, CA 92037, USA.
Shanks
T G
TG
Colt
H G
HG
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D001999:Bronchoscopy / Q000009:adverse effects*; D004285:Dogs; D053685:Laser Therapy / Q000009:adverse effects; D007834:Lasers / Q000009:adverse effects*; D008670:Metals; D023421:Models, Animal; D011474:Prosthesis Design; D012828:Silicones; D015607:Stents
D008670:Metals; D012828:Silicones