Characteristics of Nd:YAG sculptured contact probes after prolonged laser application.

This study analyzed the functional and structural characteristics of cone, hemisphere, and modified sculptured contact fibers (1,000 microns) after 1 hour of continuous Nd:YAG laser application. Continuous laser application was performed on live porcine tissue using 20 watts of power. The fiber's appearance under a microscope as well as the power output was recorded after 0, 5, 10, 20, 30, 45, and 60 minutes of continuous laser application. (N = 3 for each fiber). At time 0, all fibers transmitted from 49 to 56% of the initial 20 watts (W); power transmission decreased to less than 9% relative power transmission after 20 minutes and then plateaued. The fibers exhibited severe distortion and carbonization of the surface where laser had been applied with evidence of quartz melting and shattering after only 10 minutes. By 30 minutes of laser application, all three fibers were fractured and essentially indistinguishable from one another; moreover, the fibers exhibited similar power transmission, and cutting and coagulation activity, as determined by a panel of independent, double-blinded surgeons. These data lead us to conclude that 1) Nd:YAG contact laser effects result from thermal heating of the fiber tip with subsequent tissue injury, 2) the unique structural configuration of the fiber's sculptured tip are lost after several minutes of laser application without appreciable change in functional integrity, and 3) fibers may be manually fractured allowing for multiple uses without significant sacrifice of power transmission or surgical utility.

The effect of lasers, electrocautery, and sharp dissection on cutaneous flaps.

This study evaluated the technical ease and wound-healing response of cutaneous flaps constructed on dogs using Nd:YAG laser, CO2 laser, electrocautery, and sharp dissection. Four flaps were constructed on the dorsum of 16 dogs using each of the four modalities. Parameters examined included drainage after both 48 hours and 1 week, time of dissection, bursting strength, and semiquantitative assessments of fibroblast, polymorphonuclear leukocyte, monocyte, and collagen content. Significantly less time was required to construct flaps with electrocautery as compared with CO2 laser, Nd:YAG laser, and sharp dissection (15 versus 18, 20, and 26 minutes, respectively; p < 0.01). Significantly fewer suture ligatures were necessary to obtain hemostasis for electrocautery, CO2 laser, and Nd:YAG laser as compared with sharp dissection (0, 2, and 2 versus 15 sutures, respectively; p < 0.01). Drainage was significantly less for flaps constructed using sharp dissection as compared with both CO2 and Nd:YAG lasers at 48 hours (12 versus 26 cc, p < 0.01, and 20 cc, p < 0.05, respectively). Significantly less drainage was observed after 48 hours for flaps created using electrocautery as compared with CO2 laser (14 versus 26 cc; p < 0.05). Bursting strength of flaps constructed using sharp dissection was significantly greater than that of those constructed using electrocautery, Nd:YAG laser, and CO2 laser (1086 versus 638 gm, p < 0.05, 714 gm, and 571 gm, p < 0.01, respectively). Semiquantitative histologic evaluation revealed a higher collagen content and fibroblast infiltration and less polymorphonuclear leukocyte infiltration in wounds created using sharp dissection as compared with CO2 laser, Nd:YAG laser, and electrocautery.(ABSTRACT TRUNCATED AT 250 WORDS)