Steven K. Libutti

Preliminary Results of Laser Tissue Welding in Extra Vesical Reimplantation of the Ureters

One exciting potential use of laparoscopic technology is the extravesical reimplantation of the ureters. We have assessed the efficacy of laser-activated fibrinogen solder to close vesical muscle flaps over submucosal ureters (Lich-Gregoir technique) in a canine model. Four dogs were subjected to unilateral flap closures via a protein solder (indocyanine green and fibrinogen) applied to the bladder serosa and exposed to 808 nm. continuous wave diode laser energy. Contralateral reimplantation was performed using 4-zero vicryl muscle flap closures (controls). At 7, 14 and 28 days postoperatively, intravenous pyelograms confirmed bilateral ureteral patency. At intravesical pressures above 100 cm. H2O, there was no evidence of wound disruption in either group. Nondisrupted wound closures were sectioned and strained until ultimate breakage to determine tensile strength. At each study interval the laser-welded closures withstood greater stress than the controls. Although these data represent single tissue samples and are not amenable to statistical analysis, laser-welded closures appeared to be stronger at each study interval. In conclusion, laser-welded vesical wound closures appear at least as strong as suture closures in the canine model.

Skin closure with dye-enhanced laser welding and fibrinogen.

Skin cancers are most common cancers in human populations, with more than 550,000 new cases annually in the United States, representing at least 30% of annual primary cancer diagnosed. It has been well recognized that solar ultraviolet radiation is the predominant causal factor in cutaneous carcinogenesis in humans. The risk degree of solar ultraviolet radiation in terms of inducing skin cancers in humans varies among the population. Some of factors, such as an individuals skin type, are beyond ones control. But many of others are manageable. Among them are outdoor activity patterns and all factors related including spectrum of the ultraviolet radiation, intensity of the ultraviolet radiation and total exposure time. This paper will discuss the factors affecting the risk degree of solar ultraviolet radiation-induced skin cancers in humans and present a novel method and sensing device in order to help in preventing such cancers in humans.

Canine colonic anastomoses reinforced with dye-enhanced fibrinogen and a diode laser

SummaryLeakage from colonic anastomoses is a common cause of morbidity in patients recovering from bowel surgery. We evaluated a technique of laser-fibrinogen reinforcement to strengthen colonic anastomoses in a canine model. After creation of eight single-layer interrupted suture anastomoses in six dogs, indocyanine green-dye-enhanced fibrinogen was topically applied to the serosal surface and exposed to 808 mm diode laser energy. Immediately following colonic anastomosis, the mean leakage pressure was 137±22 mm Hg in the group (n=8) using sutures alone and 326±67 mm Hg (P<0.001) in the group (n=8) after the sutured anastomosis was reinforced with lasered-fibrinogen. On histological examination, no evidence of thermal injury to the tissue edges was noted and a layer of fibrinogen bridged the anastomotic gap. Laser dye-enhanced fibrinogen reinforcement significantly enhances the strength of sutured colonic anastomoses without causing appreciable thermal injury to the host tissues.

Laparoscopic resection of a nonparasitic liver cyst

The spectrum of treatment options for symptomatic, benign, nonparasitic hepatic cysts has ranged from percutaneous aspiration to liver transplantation. Most large series have demonstrated that complete resection of the cyst is associated with the lowest rate of recurrence. However, a conventional open laparotomy may subject these patients to unacceptable morbidity given the benign nature of most of these lesions.We successfully performed a complete resection of a large hepatic cyst using a laparoscopic approach. Using an endoscopic GIA stapling device we were able to remove the cyst with minimal blood loss and in minimal operative time. The patient tolerated the procedure well, was discharged home on postoperative day 2, and in follow-up has been without recurrent symptoms.

Sutureless Rabbit Bladder Mucosa Patch Graft Urethroplasty Using Diode Laser And Solder

Fistula and strictures at the site of sutured anastomoses are frequent complications of major urethroplasty. We harvested bladder mucosa in 26 rabbits to repair large defects in the proximal urethra using laser-activated solder in the hope that such a repair would be stronger, faster to create and avoid common complications seen with conventional repair. Large oval defects were created in the proximal urethra in all animals undergoing urethroplasty. Twelve animals underwent bladder mucosa graft closure via diode (808 nm.) laser activation of an albumin-based solder (50% were suture-free). Fourteen additional animals underwent closure with 7-zero polydiaxanone suture (controls). Leak pressure and time of repair were recorded for each graft. Additional sections of bladder mucosa were harvested, transected and repaired by laser welding to determine tensile strength. In both groups, radiography, urethroscopy and clinical course were evaluated for as much as 6 weeks postoperatively. Urethroplasty time was significantly (p < 0.01) shorter for the laser group (13.8 +/- 2.5 minutes) than for the sutured repair group (24.0 +/- 5.3 minutes). Initial leak pressures for the lasered grafts averaged at least 4 times those of sutured grafts (p < 0.01). The tensile strength for lasered bladder mucosa was 3.16 +/- 1.12 kg./cm.2 Early retrograde urethrograms (RUG) performed at 7 days (n = 5) revealed urinary extravasation and fistula formation in 2 control animals compared with a normal urethral appearance in 3 lasered repairs. Early retrograde urethrograms performed at 21 days (n = 21) demonstrated smooth-walled urethras with no evidence of fistula, stricture, or urinary extravasation in the lasered group; varying degrees of reactive mucosal proliferation were seen in the controls. Urethroscopy confirmed these observations. At 6 weeks, histologic examination confirmed the presence of viable graft in all animals. We conclude that bladder mucosa patch graft urethroplasty using diode laser welding and albumin-based solder is an attractive alternative to conventional methods.

Laser welding with albumin-based solder: experimental full-tubed skin graft urethroplasty.

Fistula and stricture formation at the site of sutured anastomoses are frequent complications of major urethroplasty. We performed urethroplasty using laser‐welded skin tube grafts in the hope that in addition to being free of suture holes, grafts would be as strong as or stronger than sutured controls.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology

Tissue welding using laser‐activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery.

Preliminary experience with laser reinforcement of vascular anastomoses

Laser tissue soldering techniques allow reinforcement of sutured repairs and may be a useful adjunct in reducing anastomotic bleeding. Initial results of our clinical trial with laser solder reinforcement are reported. Twenty-one patients underwent standard polytetraflouroethylene (PTFE) graft arteriovenous fistula (AVF) creation. In 11 patients thrombin soaked gelatin sponges were placed around the anastomoses and in 10 laser reinforcement was accomplished. Three lasers were used: KTP (532 nm, power density 4.1 W/cm2, spot size .5 cm), CO2 (10,600 nm, power density 14.1 W/cm2, spot size .3 cm), and diode (805 nm, power density 9.6 W/cm2, spot size .2 cm). The solder consisting of 0.4 cc hyaluronate, 0.2 cc albumin, and 3 drops of the appropriate laser enhancing dye (fluorescein for KTP, indocyanine green for the diode, water for CO2) was applied to the target tissues prior to laser exposure. The laser was directed over the tissue in a sweeping motion until the solder had desiccated. Several lessons are evident from our experience. First, over exposure to the laser results in solder charring and ineffective reinforcement. Greater laser exposure with less undesired solder damage is achieved if dye is added to the solder. Second, the solder should be spread over the target in a thin layer to facilitate controlled desiccation and tissue bonding. Additional layers can be applied as required. Although improvements in the solder and laser technique are required, these early results demonstrate a potential clinical use for laser soldered reinforcement during vascular anastomoses.

Comparison of laser-activated tissue solders and thrombin-activated cryoprecipitate for wound closure

To determine the relative strengths of various biologic adhesives at several timepoints, we compared thrombin-activated SD (solvent-detergent treated) cryoprecipitate with laser- activated SD cryoprecipitate and a laser-activated, albumin-based glue. Male Sprague-Dawley rats (n equals 79) received four, 3-cm, dorsal skin incisions which were closed with either laser- activated cryoprecipitate, laser-activated albumin solder, thrombin-activated cryoprecipitate, or standard skin staples. The cryoprecipitate was derived from pooled human plasma and was treated with a solvent-detergent process, rendering it free of envelope-coated viruses (i.e., HBV, HIV). An 808-nm diode laser was used to activate each solder with an average duration of exposure of 75 seconds per incision. Animals were sacrificed for evaluation of wound tensile strength and histology at 0 hours, 2 hours, 4 hours, and 4 days. At all timepoints tested, laser-activated solders were significantly stronger than thrombin-activated cryoprecipitate (p < 0.03) and control wounds (p < 0.003). There was no significant difference in tensile strength between the two types of laser-activated solder at any timepoint.

Reinforcement of high-risk anastomoses using laser-activated protein solders: a clinical study

Anastomotic leakage or breakdown can result in catastrophic complications and significantly increased post-operative morbidity and mortality. Certain anastomoses are subject to a higher incidence of disruption and are therefore termed high risk. In an attempt to decrease the risk of anastomotic leaks, we reinforced sutured anastomoses with a laser activated protein solder in patients undergoing esophagojejunostomies (n equals 2), lung transplantation (n equals 2), and pancreaticojejunostomies (Whipple procedure, n equals 5). The protein solder was composed of 1.0 ml of a 25% human albumin solution, 1.0 ml of sodium hyaluronate, and 0.1 ml of Cardiogreen dye. This composition was applied to the sutured anastomosis and activated with an 860 nm pulsed diode laser. Drains were placed when appropriate and patients were followed for up to 10 months post-operatively and assessed for clinical signs of anastomotic leaks. Results to data demonstrated that there were no immediate complications as a result of the procedure. Operative time was not significantly lengthened. There were no cases of clinically significant leakage from any of the reinforced anastomoses. Laser activated protein solders may help to reduce the incidence of leakage in high risk anastomoses. Large numbers of patients and longer follow-up is needed however, to draw significant conclusions.