Laser skin welding: in vivo tensile strength and wound healing results.
OBJECTIVE
Laser skin welding was investigated as a general model for laser tissue closure. Scanned delivery of near-infrared laser radiation in combination with a dye can produce strong welds with limited thermal damage.


METHODS
Two-centimeter-long, full-thickness incisions were made on the backs of guinea pigs. Wounds were closed either by laser welding or sutures and then biopsied at 0, 3, 6, 10, 14, 21, and 28 days postoperatively. Welding was achieved by using continuous-wave, 1. 06-micrometer, Nd:YAG laser radiation scanned over the incisions to produce a dwell time of approximately 80 msec. The cooling time between scans was fixed at 8 seconds. A 4-mm-diameter laser spot was maintained during the experiments, and the power was kept constant at 10 W. The operation time was fixed at 10 minutes per incision. India ink was used as an absorber of the laser radiation at the weld site, and clamps were used temporarily to appose the incision edges.


RESULTS
Acute weld strengths of 2.1 +/- 0.7 kg/cm(2) were significantly higher than suture apposition strengths of 0.4 +/- 0.1 kg/cm(2) (P < 0.01), and weld strengths continued to increase over time. Lateral thermal damage in the laser welds was limited to 200 +/- 40 micrometer near the epidermal surface with less thermal damage deeper within the dermis.


CONCLUSIONS
Our welding technique produced higher weld strengths and less thermal damage than reported in previous skin welding studies and may represent an alternative to sutures.
Biomedical Engineering Department, Northwestern University, Evanston, Illinois, USA. nfried@bme.jhu.edu
N M
NM
Fried
J T
JT
Walsh
D000818:Animals; D002244:Carbon; D004396:Coloring Agents / Q000627:therapeutic use; D005260:Female; D006168:Guinea Pigs; D017075:Laser Coagulation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D012867:Skin / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology; D013537:Sutures; D013718:Tensile Strength; D016896:Treatment Outcome; D014945:Wound Healing / Q000528:radiation effects*; D014947:Wounds and Injuries / Q000503:physiopathology / Q000532:radiotherapy*
D004396:Coloring Agents; C028433:chinese ink; D002244:Carbon