Sutureless bowel anastomosis using Nd:YAG laser

Bowel welding technique in dogs and cats using a diode laser: an experimental study

A laser bowel welding technique for dogs and cats was developed. The bowel was pinched using a special clamp having an opening on the body developed for this experiment (LW clamp). Using the 2 different types of contact probe (blunt tip: Laser Bipolar Dissector (LBD); sharp tip: Super Scalpel Dissector (SSD)), the laser passed through the hole in the LW clamp to cut the bowels, while at the same time, sealing the cut portion. The results obtained in this study showed that the optimum laser output using LBD was 6-10 W in dog and cat ileum, and 8-10 W in dog and cat colon. Optimum laser output using SSD was 6-8 W in dog ileum, 8-10 W in dog colon, 10 W in cat ileum and 6-8 W in cat colon. No marked differences were observed between ileum and colon when using either LBD or SSD. At the same power, burst pressure tended to be slightly higher with LBD than with SSD, although there were not significant differences between them. Histologically, complete sealing of the welded site was seen. Welding and cutting of bowel in dogs and cats was thus confirmed to be possible using the LW clamp in combination with LBD or SSD probes under a diode laser output of approximately 8 W for 50-80 s (400-640 J/cm). Thus, we can expect that this method is applicable to clinical veterinary medicine.

NIR laser tissue welding of in vitro porcine cornea and sclera tissue

BACKGROUND AND OBJECTIVE

The objective of this study was to test the hypothesis that an near infrared (NIR) laser system (1,455 nm) in combination with a motorized translational stage to control the position and speed of the laser beam and a shutter to control the laser exposure to the tissue being welded could be used to successfully weld ocular tissues.

STUDY DESIGN/MATERIALS AND METHODS

Seventy-five porcine corneas and 23 porcine scleral tissues were welded in vitro in this study. The welded tissues were examined using histopathology and tensile strength analysis. Eight different welding conditions were analyzed for porcine cornea and one for sclera tissues. The tensile strength of the welded groups was compared to a sutured cornea control group.

RESULTS

The NIR laser welding system provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. Mean weld strengths of 0.15-0.45 kg/cm(2) were obtained for the cornea and 1.01 kg/cm(2) for sclera welds. The native H(2)O in the ocular tissue serves as an absorber of the 1,455 nm radiation and helps to induce the welds.

CONCLUSIONS

We conclude that an NIR laser system using an optimal laser radiation wavelength of 1,455 nm can effectively weld cornea and sclera tissue and that this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity. The optimization of a laser welding system that leads to a strong full thickness tissue bond without tissue destruction, an instant seal that promotes wound healing, and the absence of a continued presence of a foreign substance like a suture, is of considerable importance to the ophthalmology medical community. This need is especially apparent with respect to corneal transplantation and fixing the position of corneal flaps in Laser-Assisted In Situ Keratomileusis (LASIK), a laser procedure used to permanently change the shape of the cornea.

Ex vivo evaluation of human fetal membrane closure

BACKGROUND AND OBJECTIVE

This study compares stress and leak point pressure of human fetal membranes following closure with suture, laser welding, or a new tissue sealant, SynthaSeal.

STUDY DESIGN/MATERIALS AND METHODS

Samples of fetal membrane were bisected and repaired with suture, laser welding with albumin solders, or a tissue sealant. Representative tissue samples were assessed by histology. Anastomotic strength was evaluated by tensiometry. Additionally, leak pressure was measured after membrane samples were placed onto an infusion pump/pressure transducer, incised, and repaired as above.

RESULTS

Membrane stress was strongest (P<0.001) for the tissue sealant group. Sutured samples were stronger than laser-welded samples. Membrane leak pressure was greatest for the tissue sealant group. The suture group demonstrated a higher leak pressure than the laser-welded group.

CONCLUSIONS

Human fetal membranes were not suited for repair with laser welding under the conditions tested. A new tissue sealant, SynthaSeal, may provide a simple, effective method for membrane closure following fetoscopy, amniocentesis, and open fetal surgery.

Evaluation of octylcyanoacrylate for wound repair of clinical circumcision and human skin incisional healing in a nude rat model

PURPOSE

Alternative methods of circumcision wound closure have been studied to decrease repair time and complications, and improve cosmesis. This study includes a clinical and a laboratory research portion. Clinical parameters, wound outcome, closure time and operative time were compared for octylcyanoacrylate and suture approximation of circumcision incisions. An in vivo incisional model using human foreskin was used to compare the wound breaking strength of octylcyanoacrylate and suture repair.

MATERIALS AND METHODS

Circumcision incisions were closed with suture or octylcyanoacrylate. Wound closure time and operating room time were recorded. Patients were evaluated 1 and 12 weeks postoperatively. Foreskin samples from another group of patients were engrafted to an immunodeficient rat and allowed to heal. Incisions were made in the human skin and the wounds were repaired with sutures or octylcyanoacrylate. After 7 days breaking stress was tested and healing was evaluated by histological testing.

RESULTS

Optimal wound healing was noted in all patients 1 week after surgery. Scarring was absent in the octylcyanoacrylate group. Octylcyanoacrylate closure time was significantly shorter than suture time (p <0.001). Mean total operating room time for octylcyanoacrylate plus or minus standard deviation was shorter than for suture (19.4 +/- 0.51 versus 26.9 +/- 0.94 minutes, p <0.001). Octylcyanoacrylate wound breaking stress was equivalent to suture on tensiometry. Histological testing revealed normal healing in all wounds.

CONCLUSIONS

Circumcision wounds may be closed by octylcyanoacrylate with shorter wound closure and operative time than by suture. In an animal model of human skin healing, wound breaking stress after octylcyanoacrylate closure was equivalent to suture repair. Octylcyanoacrylate may be a useful alternative to suture closure for circumcision incisions.

Concentrated autologous plasma protein: a biochemically neutral solder for tissue welding

BACKGROUND AND OBJECTIVE

Xenographic or allographic serum protein solders used for laser welding may have immunologic and/or pathogenic complications. The objective of these studies was to develop a safe, autologous solder.

STUDY DESIGN/MATERIALS AND METHODS

Five methods of preparing concentrated autologous plasma protein solder (CAPPS) were evaluated. Next, the CAPPS was evaluated via (1) thermal denaturation studies using differential scanning calorimetry, (2) tissue welding studies to characterize both acute and healing properties.

RESULTS

The optimal concentration method to produce CAPPS rapidly was a dialysis method using chemical (osmotic) forces. The CAPPS showed similar denaturation profiles to serum albumin (SA) solders. Acutely, CAPPS provided comparable breaking strengths to SA solders. At 7 days, there was no significant difference in breaking strength or histology between 50% human SA solder and CAPPS (using a porcine skin model).

CONCLUSIONS

These studies demonstrate that the CAPPS system provides acceptable acute and chronic properties for laser welding.

Laser tissue welding: a biotechnological advance for the future

Laser tissue welding as well as other alternative methods of closure will play a more important role in surgical specialties as laparoscopic, endoscopic, and microsurgical techniques continue to develop. Laser tissue welding uses laser energy to anastomose tissues and is ideally suited for applications in which suturing and stapling is difficult. Recent advances have led to a better understanding of the mechanisms of tissue welding. Additionally, technical achievements including the introduction of protein solders and temperature-controlled feedback systems have led to the acceptance of laser tissue welding in clinical medicine. In this article, we describe the history and development of laser tissue welding and review the current and potential applications of this technology.

Differential scanning calorimetry of albumin solders: interspecies differences and fatty acid binding effects on protein denaturation

BACKGROUND AND OBJECTIVE

Understanding albumin solder denaturation is important for laser tissue soldering. Human (HSA), bovine (BSA), porcine (PSA), and canine (CSA) albumin both fatty acid containing (FAC) and fatty acid free (FAF) were evaluated by using differential scanning calorimetry (DSC).

STUDY DESIGN/MATERIALS AND METHODS

DSC was used to measure difference thermograms to determine the irreversible thermal denaturation profile for 50% albumin solutions. The denaturation transition's onset, end and peak temperatures, and enthalpy were measured.

RESULTS

All FAC species, except BSA, exhibited twin peaked endotherms. Single endotherms were observed for all FAF species and BSA-FAC. Onset and end temperatures were significantly [P < 0.001] lower for all FAF species (except BSA's end temperature). There was a 30% decrease in the denaturation enthalpy between FAF and FAC groups.

CONCLUSION

FAF albumin solders were found to denature at significantly lower temperatures, while also having a 30% reduction in enthalpy when compared with their FAC counterparts.

Semi-solid albumin solder improved mechanical properties for laser tissue welding

BACKGROUND AND OBJECTIVE

A semi-solid albumin solder formulated with hydroxypropylmethylcellulose (HPMC) was designed to improve the characteristics of liquid and solid solders.

STUDY DESIGN/MATERIALS AND METHODS

Acute tensile strengths were determined on canine small bowel in vitro by using liquid 50% bovine serum albumin (BSA), semi-solid 48% BSA with HPMC, and solid 60% BSA solder. Long-term healing of liquid and semi-solid solders, compared with a suture control, was evaluated in a porcine skin model, with tensile strength as well as histologic findings obtained on postoperative day 7.

RESULTS

Acutely, semi-solid solder demonstrated a significantly (P < 0.05) higher tensile strength when compared with liquid or solid solder. At 7 days, HSA semi-solid and BSA semi-solid had significantly (P < 0.05) higher tensile strength than suture control; however, no differences were seen for liquid or solid solder groups. No differences in histology were appreciable between any of the solder groups in a porcine skin model.

CONCLUSION

Acutely and at 7 days, semi-solid solder was stronger than 50% liquid albumin with better handling characteristics.

Welding characteristics of different albumin species with and without fatty acids

BACKGROUND AND OBJECTIVE

Albumin solders from different species have been used for laser tissue welding without a complete understanding of possible differences between them. The breaking strength of four different species of serum albumin (human, bovine, porcine, and canine), both fatty acid containing (FAC) and fatty acid free (FAF), was determined to evaluate the welding ability of each type of albumin. STUYDY DESIGN/MATERIALS AND METHODS: Acute breaking strengths were determined on canine small bowel by using 50% albumin (FAF and FAC) from human, bovine (BSA), porcine, and canine species.

RESULTS

BSA-FAC and BSA-FAF had a significantly higher (P < 0.05) breaking strength than all other groups; furthermore, BSA-FAC was significantly higher (P < 0.05) than BSA-FAF. There was no significant difference in breaking strength when FAF albumin was compared with FAC albumin from humans, pigs, or dogs.

CONCLUSION

These experimental results show that species-specific and fatty acid-specific differences exist when these albumin solders are used for laser tissue welding. This finding suggests that modifications in albumin could be used to improve results through decreased thermal damage and increased weld strength.

Healing in the gastrointestinal tract

Healing in the GI tract is rapid when free of complications: Unlike cutaneous healing, in which progress can be observed on a daily basis and intervention instituted early if necessary, healing of the intestinal anastomosis is anatomically obscured from inspection, allowing the surgeon only the patient's parameters of general well-being to judge the success of the operation. For the same reason, complications usually require re-operation, with the associated morbidity of a laparotomy and additional general anesthetic. This places a great responsibility on the surgeon to be cognizant of all the preoperative, intraoperative, and postoperative factors relating to anastomotic healing that might compromise the healing process. Bearing these in mind, along with attention to technical detail, should limit complications to an acceptable level. Patients most at risk are (1) those who perioperatively develop physiologic problems that lead to shock, hypoxia, and resultant anastomotic ischemia, (2) those with radiation-induced tissue injury, (3) those with sepsis, and (4) those with preoperative bowel obstruction. Malnourishment, malignancy, diabetes, steroids, and age also influence outcome to varying degrees. Future advancement in the field of GI healing lies in our ability to manipulate the early struggle between collagen synthesis and collagen breakdown. A profound understanding of the molecular and biochemical pathways and the factors that control them will bring us closer to this goal. Clinically, this may be accomplished by the introduction of wound healing enhancers into the anastomotic site, possibly by incorporating them into suture materials, biofragmentable anastomotic rings, or staple materials. Already much is known about the influence of different cytokines and growth factors on collagen regulation, knowledge that will help resolve many of the long-standing problems associated with GI surgery.

Experimental oesophagogastric anastomosis: preliminary report of a new compression device that also fragments

Fifteen Beagle dogs underwent oesophagogastric anastomosis with a new device which enables a 'sutureless' compression anastomosis. The device fragmented and was passed in bits anally without causing obstruction. Immediate bursting pressure, tested in five dogs, was between 175 and 190 mmHg. The anastomoses of the remaining dogs were examined macroscopically and microscopically from day 6 to day 30. Healing was excellent with good muscular apposition and minimal residual inflammation.

Controlled temperature tissue fusion: argon laser welding of canine intestine in vitro

BACKGROUND AND OBJECTIVE

Thermal denaturation of proteins is recognized as a rate process governed by the local temperature-time response and is believed to be the principal mechanism for photothermal tissue welding. Since rate processes are exponential with temperature, feedback control of tissue surface temperature is hypothesized to create a quasi-constant rate of denaturation that will enhance the tissue welding process.

STUDY DESIGN, MATERIALS AND METHODS

Controlled temperature tissue welding of severed edges of fresh canine jejunum was performed in vitro by remote sensing of tissue surface temperature with an infrared sensor. A hardware controlled temperature feedback system opened and closed a shutter located in the beam path of an argon ion laser to provide constant temperature welding.

RESULTS

Strong tissue fusion was not possible at or below a surface temperature of 70 degrees C, but was accomplished at 80 degrees, 90 degrees, and 95 degrees, and 100 degrees C. Fusion was achieved with thermal coagulation of the collagenous submucosa and mucosal tissues. The bursting strength of welds created at 90 degrees C and 95 degrees C were significantly stronger than those performed at 80 degrees C.

CONCLUSION

Laser-assisted intestinal anastomoses created in vitro are optimally strong at 90-95 degrees C feedback control temperatures.

Prevention of pharyngocutaneous fistulas by means of laser-weld techniques

Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

Laser patch welding: experimental study for application to endoscopic closure of bronchopleural fistula, a preliminary report

BACKGROUND AND OBJECTIVE

Postoperative bronchopleural fistula is a serious complication following pulmonary resection. To close the bronchopleural fistula, we developed a new method of endoscopic patch welding using laser tissue welding between bronchial tissue and a patch.

STUDY DESIGN/MATERIALS AND METHODS

The feasibility of the laser patch welding was examined by in vitro and in vivo animal experiments. A newly developed carbon monoxide (CO) laser and an Argon ion laser were evaluated. Various tissue membranes and artificial membranes were evaluated as patch materials.

RESULTS

We found that the combination of expanded polytetrafluoroethylene (e-PTFE; 200 microns in thickness) and the CO laser with contact irradiation method offered the strongest laser patch welding. Using this combination, the irradiation at 400 W/cm2 for 10 seconds resulted in 16-18 g of measured traction strength at the welding spot (2 mm in diameter). The welded e-PTFE patch at bronchial stump remained for 5 weeks.

CONCLUSION

Our results encourage use of this novel laser patch technique for clinical applications.

Laser tissue welding: a comprehensive review of current and future clinical applications

Laser techniques for joining tissue, in combination with other surgical technologies, will be a hallmark of surgery in the next century. At present, there are many clinical applications of tissue welding and soldering which are beginning to achieve wide spread acceptance. These exciting clinical developments are the result of many advances which have been made in the past few years in our understanding of the mechanism of laser tissue welding. Also contributing to this progress are many important technical refinements such as tissue solders and feedback control of the laser device. In this article, we describe in depth the history and development of laser tissue welding including key theoretical concepts as well as crucial experiments which have added to our insight into this phenomenon. We also review the evolving concepts of its clinical application and indicate clinical applications which are likely to become more important in the future.

Healing process of laser-welded intestinal anastomosis

Intestinal welding by means of low-power laser has been reported as an efficient method for intestinal anastomosis. We designed an experimental model in rats to investigate collagen and DNA concentrations in CO2 laser-welded anastomoses as compared with those in sutured anastomoses on the 4th, 7th, and 10th postoperative days. The results revealed that DNA, total collagen, and insoluble collagen concentrations were significantly lower in the lased anastomoses than in the sutured anastomoses on the 4th postanastomotic day. On the 7th and 10th postanastomotic days, collagen concentrations increased in the laser-treated group attaining significantly higher levels than in the sutured group at that time. These findings are compatible with other studies demonstrating that laser-welded intestinal anastomoses are more prone to dehiscence during the first 4 postanastomotic days, but become at least as effective as the sutured ones with passage of time.

Laser welding of fascial grafts and its potential application in tympanoplasty: an animal model

This study evaluates the welding effect of argon laser on fascial grafts and its potential application in tympanoplasty. An animal model was designed so that surgically induced perforations of the lumbar fascia of the animals were grafted in an underlay fashion. Each graft was "spot welded" around the circumference of the perforation using a hand-held argon laser. Various lasing parameters were used on different grafts. Control perforations were grafted but not welded. A total of 96 perforations was studied. Weld sites were evaluated both histologically and by tensile strength measurement at the end of surgery, and at 7, 14, and 21 days postoperatively. Comparison with controls showed a higher tensile strength for welded grafts, which was most significant in the early postoperative period (p < 0.001). Histologically, it seems that the basic mechanism of fascial welding involves liquification and denaturation of extravasated proteins at the weld sites. Correlation between the extent of thermal damage on the tissues and the various lasing parameters is described. Based on the well-documented safety of argon laser in otologic surgery, and the successful welding of fascial grafts in this study, argon laser may prove beneficial in welding temporalis fascia grafts in tympanoplasty.

First experimental sutureless end-to-end laser anastomosis of the large bowel. Short-term results

Completely sutureless end-to-end large bowel anastomoses were successfully created in New Zealand white rabbits (n = 26) by using a low-energy (0.4-W wave of power) Nd:YAG laser to produce welded anastomoses. In this study, the short-term integrity, degree of narrowing, macroscopic appearance, and microscopic findings were compared with those of the conventional interrupted one-layer anastomosis (n = 24) at zero, one, four, and seven days after surgery. Two rabbits in the laser group died from leakage. All remaining animals had an uneventful postoperative course. The bursting pressures in the laser group at zero, one, and four days were lower than those in the control group. The narrowing index of the laser anastomosis was higher than that of the suture anastomosis at four and seven days. However, the laser anastomoses showed fewer adhesions, no instances of bowel obstruction, and histologic healing with less fibrosis. The technique of laser anastomosis presents a promising alternative to suturing in reconstitution of the large bowel.

Hypospadias repair using laser welding of ventral skin flap in rabbits: comparison with sutured repair

We tested the feasibility of laser welding in hypospadias repair. A total of 30 New Zealand white rabbits (2 groups of 15) underwent creation of distal hypospadias. In the control group ventrally placed skin flaps were created and sutured to the urethra. In the experimental group the ventrally placed skin flaps were welded to the urethra using a continuous wave diode laser (808 plus or minus 1 nm., 6.25 watts per cm.2). The welded anastomoses were strengthened by applying a solder of fibrinogen combined with a laser energy-absorbing dye. No stents were left indwelling. Operative time using laser welding was considerably less than that with sutured repair. No fistulas were seen in the welded urethras, and no significant foreign body reaction was identified in the laser welded repairs. Hypospadias repair in the rabbit using the laser welding technique seems to be a feasible alternative to suture repair. Topical energy-absorbing dyes that enhance thermosetting solders further increase weld strength while reducing collateral thermal damage to target tissues.

First sutureless closure of a colotomy: short-term results of experimental laser anastomosis of the colon

To assess the possibility of laser anastomosis of the colon, experimental laser closure of colotomies was performed. Transverse colotomies (average 20.7 mm) in New Zealand white rabbits (n = 20) were closed with a 1,064-nm Nd:YAG laser at a pulsating 0.5-W wave of power, using guy sutures to approximate the tissue edges. The laser energy was applied through a specially designed hand piece and hand-held 600-microns gas-cooled noncontact quartz fiber to produce a satisfactory tissue welding. Similar colotomies were closed using a single layer of interrupted sutures of 5-0 Maxon (Davis & Geck, Pearl River, NY) in a control group (n = 20). Bursting pressure and index of narrowing were recorded immediately after anastomosis and at 1, 4, and 7 days following surgery. Bursting pressure of the laser-welded closure at 1 day was significantly lower than that of the sutured controls (P less than 0.01); however, all rabbits recovered uneventfully. There was a marked decrease in adhesion formation following laser anastomosis (P less than 0.05). Conversely, one control rabbit showed functional stenosis at 4 days. Histologic study revealed an accelerated healing in the laser group. The index of narrowing was significantly higher in the laser group than in the control group (P less than 0.05). The completely water-sealed laser anastomosis reduces adhesions and is comparable to conventional suture anastomosis of the colon.

Sutureless intestinal anastomoses

Sutureless intestinal anastomoses can be achieved either by compression, where two inverted rings of bowel are compressed by a hollow circular device that subsequently sloughs away and is passed anally, or by the use of tissue glues or laser welding. Compression devices used clinically with success are the Valtrac biofragmentable anastomotic ring, the polypropylene rings described by Rosati and the AKA guns. Glued anastomoses have only been used in animals and seem to be unsafe. However, laser-welded intestinal anastomoses appear highly promising in experimental studies and further development of this technique is warranted.

The single-layer continuous suture for gastric anastomosis

The single-layer continuous suture technique has proven to be safe for all intestinal anastomoses of intraperitoneal small and large bowel segments. Since 1985, this technique has also been increasingly applied for gastroduodenostomy and gastrojejunostomy following partial gastrectomy. Through December 1989, we performed 96 gastroenteric anastomoses with the single-layer continuous suture technique. This accounts for 64% of all partial gastrectomies performed between 1985 and 1989. The technique was applied in 89.5% of the gastroenteric anastomoses during 1988 and 1989. The rate of complications after gastroenteric single-layer continuous suture technique was low; 2.1% clinical leakage was found, always in patients with perforated ulcer and peritonitis. We conclude that the single-layer continuous suture technique for gastroenteric anastomosis is safe, simple, easy to perform, quick and reliable.

Sutureless end-to-end bowel anastomosis using Nd:YAG and water-soluble intraluminal stent

Sutureless end-to-end intestinal anastomoses were successfully constructed in 20 rabbits. A water-soluble intraluminal stent was used to approximate the tissue edges, and the anastomotic seam was lased with 1.06 microns neodymium:YAG (Nd:YAG) laser energy supplied through a hand-held 600-microns gas-cooled noncontact optical fiber. A continuous 5-watt wave of power was applied over periods ranging from 46 to 92 seconds to produce the tissue blanching and shrinkage that indicated a satisfactory tissue weld. Integrity, degree of tissue reaction, and bursting pressures of the anastomoses were compared to those of anastomoses constructed using standard sutured techniques. The results of the two methods were equivalent at 1 to 3 days, but the laser-fused enteric anastomoses showed less inflammatory reaction and greater bursting pressures at 7 and 14 days. Application of a variety of proteinaceous solutions including extracellular matrix materials and epidermal growth factors prior to lasing failed to augment wound healing. We conclude that lasers show promise as reconstructive, in addition to ablative, surgical instruments.

The first sutureless, laser-welded, end-to-end bowel anastomosis

The use of laser energy to weld together tissue offers great promise in the expanding field of laser surgery. The published results of laser welding intestinal tissue have, to date, been limited to the successful laser closures of small enterotomies. This is the first report of using laser energy alone to create an end-to-end small bowel anastomosis. A biocompatible, water-soluble, intraluminal stent was employed during the laser welding of this sutureless, stapleless ileal anastomosis in a rabbit model. Excellent recovery and healing were observed. The rapidity, ease, and potential for full precision automation of laser welding mandates further research.

In utero fetal surgery using a milliwatt carbon dioxide laser

In utero surgery represents a future new frontier with unknown possibilities for medical intervention. Since the presently available microsurgery instruments are too cumbersome or indelicate, low-energy carbon dioxide lasers have been investigated as a tool that holds promise as a fetal scalpel and hemastatic device. Preliminary results demonstrate that continued investigation is necessary to limit the zone of tissue destruction in these most diminutive patients.

The use of lasers in pediatric surgery

This report is a condensation of the Fred McLoed Lecture given at the Annual Meeting of the Canadian Association of Paediatric Surgeons. It briefly cites the basic fundamentals of lasers, the characteristics of those used in surgery, and their delivery systems. The advantages of laser surgery include the sealing of blood vessels, lymphatics, and nerve ends when used for cutting. This results in a relatively dry field of surgery and less postoperative pain. There is reduced opportunity for contaminants in a clean wound, and no spreading of infection in a contaminated one. Surgery can be carried out in confined areas in a drier field of view, and can be brought to small areas by fiberoptic cables. Highly precise and localized microsurgery is possible. The use of lasers is indicated in operations where significant blood loss is expected and in patients with bleeding tendencies. It is useful in surgery for malignant disease and through highly infected tissue. Other general indications are discussed. Specific surgical procedures where lasers have been useful include treatment of hemangiomas, surgery of the tongue, repair of pectus excavatum, partial splenectomy and splenic repair, hepatic lobectomy and hepatic repair, and resection of adrenal tumors. Lasers have also been useful in partial nephrectomy, excision biopsy, revision or closure of ileostomy or colostomy, endorectal mucosectomy, posterior sagittal anorectoplasty, treatment of condyloma acuminata, burn wound debridement, and infected tissue debridement. Anticipated uses include vascular, biliary tract, and intestinal repair and anastomoses, and photodynamic therapy (PDT) of neoplasms.

Laser-assisted intestinal anastomosis

Laser-assisted tissue fusion has been investigated as a new technology to enhance the healing of soft tissues. Laser fusion of intestinal anastomoses shows promise as a method to obtain primary healing while eliminating a foreign-body reaction associated with the sutures. This paper reviews the experimental data that are available regarding laser-assisted intestinal anastomoses and summarizes our experience using the CO2, Nd:YAG, and argon lasers to form fusions in small bowel.

Low-energy CO2 laser intestinal anastomosis: an experimental study

Intestinal anastomosis was performed in 17 Wistar rats via tissue welding by the low-energy CO2 laser. The postoperative course in the animals studied was uneventful. The integrity of the anastomosis was investigated manometrically, immediately upon completion of the anastomosis as well as 20 days later. Ten additional Wistar rats served as controls in which conventional interrupted one-layer anastomosis was performed. The results show a significant superiority of the intestinal anastomoses that were constructed by means of laser tissue welding. The time to complete the anastomosis was also significantly shorter when laser rather than manual suturing was used. Serial histological examinations for up to 90 days following surgery revealed complete healing and epithelization of the anastomotic site.

Closure of rabbit ileum enterotomies with the argon and CO2 lasers: bursting pressures and histology

In this study, we examined short-term strength and histology of experimental argon and CO2 laser-welded and control-sutured enterotomies in a rabbit model. Longitudinal 1.0-cm enterotomies were closed with the argon laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 2.8 mm resulting in energy fluences of 230 and 450 J/cm2, respectively. Similar enterotomies were closed using the CO2 laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 1.2 mm, resulting in energy fluences of 1,360 and 2,730 J/cm2. In all closures, continuous wave laser was delivered for 30 seconds. Using a pressure-monitored infusion system with normal saline, the pressure required to burst each weld as well as sutured controls (n = 10) was recorded approximately 1 minute following fusion. Mean bursting pressures for the argon laser at 0.5 W and 1.0 W were 34.1 +/- 19.4 mm Hg (mean +/- SD) and 17.3 +/- 8.3 mm Hg, respectively, and for the CO2 laser were 23.5 +/- 12.0 mm Hg and 31.8 +/- 15.6 mm Hg, respectively. Sutured controls leaked at 45.2 +/- 12.0 mm Hg. With the exception of argon-laser welds at an energy fluence of 450 J/cm2, which were less than sutured repairs, the bursting pressures for welded closures were not significantly different from the sutured controls (Student's t distribution, P less than .05). Histologic examination of both types of welds demonstrated a fibrin and red blood cell coagulum bridging the anastomosis, with some evidence of mild thermal injury at the mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)