Richard Lyons

Skin closure by Nd: YAG laser welding

Skin incisions 6 mm in length were made on the backs of hairless mice. Control wounds were closed with interrupted 5-0 Prolene sutures, and experimental wounds were approximated and closed by laser welding using a Nd:YAG laser. The wounds were examined daily, and specimens were excised at weekly intervals for histopathologic study, transmission electron microscopy, tensile strength determination, and type I collagen-specific messenger ribonucleic acid measurements. The laser-welded wounds demonstrated rapid healing. Histologic study showed a functional scar tissue at day 7 and a minimal residue of the original wound at day 14. Tensile strength of the control and experimental wounds was similar at all time points. The levels of collagen-specific messenger ribonucleic acid were significantly higher in the sutured group in comparison with the laser group or with normal control skin. This study suggests that laser welding might have advantages over suturing, since the former is sterile and nontactile, does not require introduction of foreign material into the wound, and provides subjectively improved cosmetic results.

Argon laser-welded arteriovenous anastomoses

This study compared the healing of laser-welded and sutured canine femoral arteriovenous anastomoses. Arteriovenous fistulas 2 cm in length were created bilaterally in the femoral vessels of 10 dogs and were studied at 1 (n = 2), 2 (n = 2), 4 (n = 3), and 8 (n = 3) weeks. In each animal, one anastomosis (control) was closed with running 6-0 polypropylene sutures, and the contralateral anastomosis (experimental) was sealed with an argon laser (0.5 watt, 4 minutes of exposure, 1830 J/cm2/1 cm length of anastomosis). At removal all experimental anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 4 weeks revealed that laser-welded anastomoses had less inflammatory response and almost normal collagen and elastin reorientation. At 8 weeks sutured anastomoses had significant intimal hyperplasia whereas laser repairs had normal luminal architecture. Tensile strength and collagen production, measured by the synthesis of hydroxyproline and the steady-state levels of type I and type III procollagen messenger ribonucleic acids, at the anastomoses and in adjacent vein and artery specimens were similar in sutured and laser-welded repairs at 2, 4, and 8 weeks. We conclude that argon laser welding of anastomoses is an acceptable alternative to suture techniques, with the advantage of improved healing without foreign body response and possible diminished intimal hyperplasia at the anastomotic line.

Laser welding: An alternative method of venous repair

This study compared the histology, biochemistry, tensile strength, and extensibility of Nd:YAG laser-welded and sutured venotomies. Two-centimeter-length bilateral canine femoral or jugular venotomies were evaluated with one vessel (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral vessel (experimental) welded with the Nd:YAG laser (1 W power and 30- to 40-sec exposure). Specimens were removed and examined immediately after fashioning (t0) and at 1, 4, or 5 weeks post-operatively to compare the progression of healing. Histologic examination of the 4- and 5-week sutured wounds had granulomatous reaction around the sutures with areas of excessive collagen accumulation. In contrast, the laser-welded wounds had minimal inflammatory response, near normal collagen content, and minimal residual disorientation and break in the elastic fiber continuity. The rate of collagen synthesis in laser-welded wounds was approximately twice that of sutured wounds at 1, 4, and 5 weeks, and correlated with increased tensile strengths of lasered wounds. The extensibility of the 5-week specimens was 0.19 for sutured and 0.29 for laser-welded wounds as compared to 0.29 for normal vein. These preliminary data suggest that laser welding of venotomies may have several advantages over conventional suture techniques.

Preliminary report: a new technique of enterotomy closure using Nd:YAG laser welding compared to suture repair

This study compared the histology and tensile strength of Nd:YAG laser welded and sutured small bowel enterotomies in Sprague-Dawley rats. Enterotomies (0.5 cm long) were either welded with the Nd:YAG laser (1 W and 10.6 sec pulses) or repaired with interrupted, simple 6-O silk sutures. Group I consisted of seven animals; five with enterotomies repaired by laser welding and two repaired by suturing. Group II consisted of eight animals with each having both laser and suture repairs. Animals were killed and specimens were removed and examined at 1 day, and at 1, 2, and 3 weeks postoperatively to compare the progression of healing. On macroscopic examination the laser welded enterotomies were closed 84% of the time and only 23% had adhesion formation while 90% of sutured repairs were closed and 100% had adhesion formation. Histologic examination of both suture and laser welded enterotomies demonstrated active healing at 1 week with minimal collagen bridging the enterotomies. At 2 and 3 weeks the sutured enterotomies had granulomatous reaction around the sutures while the laser welded enterotomies had minimal inflammatory response and near normal small bowel histology. The tensile strength of the 3-week specimens from both the suture and laser welded enterotomies were 50% of normal bowel. These findings suggest that the laser welding of small bowel enterotomies is comparable in closure and tensile strength to suture repair. The time required to repair the enterotomy is significantly decreased, the procedure is easily performed, and there is a marked decrease in adhesion formation following laser repair.

Vascular Welding Using The Argon Laser

This study compared the histology, biochemistry, and tensile strength of laser welded and sutured canine venotomies, arteriotomies and arteriovenous fistulas. Bilateral femoral, carotid or jugular vessels were studied with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralatral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks for each type of repair and evaluated histologically by hematoxylineosin, elastin and trichrome stains, biochemically by the formation of [3H] hyaroxyproline as an index of collagen synthesis, ana mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welaing may be an alternative to sutures for repair of large diameter venotomies, arteriotomies and arteriovenous fistulas, as they heal comparable to suture repairs up to 4 weeks postoperatively.

Wound Repair By Laser Welding

In this study, we have developed a concept of wound closure by laser welding and studied the wound healing process. In the first set of experiments, six-millimeter long, full-thickness incisions were made in the skin on the back of hairless mice. Control wounds were closed with interrupted 5-0 prolene suture. The experimental wounds were approximated and closed by laser welding using a Nd:YAG (1.06 μm) laser. Selected wounds were excised for histopathology, transmission electron microscopy, tensile strength determination and assay of type I collagen specific messenger-RNA. The laser welded wounds demonstrated rapid healing with good cosmetic results. The tensile strength was identical both for laser welded and sutured wounds at 7, 16, and 21 days. A significant increase of type I collagen specific mRNA was noted in both specimens at 4, 10 and 16 days, but a higher level was recorded in the sutured specimens at day 16 (2652 vs. 911 U/pg total RNA). We further initiated a comparative study to identify the laser which would be most suitable for skin welding. For this purpose argon, Nd:YAG (1.06 μm and 1.32 μm) and CO2 lasers were used to weld skin. Wound healing, tensile strength and collagen analyses were performed. The results indicated that both argon and Nd:YAG (1.32 μm) lasers achieved the most effective closure. These results suggest that laser welding provides an efficient method for closing skin wounds. The laser welding has clear advantages over conventional suturing techniques, being sterile, non-tactile, not requiring introduction of foreign materials into the wound, and providing improved cosmetic results.

Stimulation Of Wound Healing By Lasers

Clinical observations have suggested that low energy lasers might stimulate wound healing. To understand the mechanism of the biostimulation, we have previously examined the effects of low energy lasers on collagen production by human skin fibroblasts and reported an increase of collagen synthesis in vitro (J. Am. Acad. Derm. 11:1142-1150, 1980. To examine the effects of low energy lasers in vivo, hairless mice were experimentally wounded, sutured and subjected to laser irradiation by He-Ne laser with a power output of 1.56 mW, and an energy fluence of 1.22 J/cm2. Experimental wounds were subjected to laser treatment every other day, for a total duration of 2 months; control wounds remained untreated. Specimens from the wounds were then examined for histology, tensile strength and total collagen content. Results demonstrated a considerable improvement of the tensile strength of the laser-irradiated wounds at 1 and 2 weeks. Furthermore, the total collagen content was significantly increased at 2 months when compared to control wounds. These results suggest a beneficial effect of He-Ne laser on wound healing in vivo.

CO 2 , Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG), And Argon Laser Welding Of Vascular Tissue

Tne feasibility of welding thin-walled microvessels by laser has been established. This report summarizes our experience using laser welding to repair thick-walled, large-diameter, 4 to 8 mm canine veins and arteries using CO2, Nd:YAG and argon lasers. Welding of venotomies is uniformly successful using CO2 and Nd:YAG lasers, and Nd:YAG venotomies appear to veal more rapidly than sutured controls. Arterial welding has been accomplished with the Nd:YAG and argon laser. Our preliminary experience shows promise for welding both large diameter veins and arteries using lasers. Laser welding may represent an alternative for repair of small and large diameter vessels with several advantages compared to conventional suture techniques.