Introduction: Laparoscopic pyeloplasty is used for the repair of uretero-pelvic junction (UPJ) obstructions. Our aim was to do it using laser tissue soldering.
Materials and Methods: We developed a tissue bonding system based on a CO2 laser, a temperature detector and infrared
transmitting optical fibers, to obtain temperature controlled laser soldering of incisions. The system was then adapted for
laparoscopic soldering of ureters of pigs.
Results: We successfully carried out laparoscopic pyeloplasty in a porcine model, using a procedure based on CO2 laser
soldering.
Conclusions: Laparoscopic laser soldering was found to be faster than suturing, it was easier to use and provided watertight bonding. This technique will be useful in other surgical procedures.
Background and objectives: Conventional methods for microvascular anastomosis are normally based on suturing, using special thin nylon sutures. These methods suffer from major drawbacks, which include: anastomosis, which is not watertight, and sutures or clips that cause an inflammatory response. In order to obtain better results, we introduced a procedure based on CO2 laser soldering. We tested the system on arteriotomy incisions in rat blood vessels, in vivo.
Materials and methods: We used a fiber optic based laser soldering system, with a temperature control capability. Arteriotomy incisions of lengths 4±1mm were performed on the femoral arteries of 48 wistar rats: 24 rats in the control group (suture) and 24 rats in the test group (laser soldering). We conducted two follow-up periods: 7 days and 21 days after the surgical procedure, for each group. Flow tests and histology examination were done in order to evaluate the
quality of the procedures.
Results: The patency rate was 84% for both groups, soldered and sutured. The sutured group showed a significant foreign body reaction (p < 0.05), which was not observed in the soldered group. We found no evidence of thermal damage in the soldered blood vessels.
Conclusions: We can conclude that laser soldering is a less traumatic procedure, compared with the conventional suturing technique. It is potentially a faster technique and easier to master.
Objectives: To determine the feasibility and reproducibility of laser soldering of cornea using biolog ical solder and a fiberopitc temperature conrolled CO2 laser system. Methods: We developed a system based on IR fiber delivery of CO2 laser radiation, for heating a spot on tissue, a fiberoptic radiometer for non-tactile infrared thermometry of the heated spot, and a computer control of the temperature of the spot.Experiments were performed in vivo in 8 corneas of 12Kg piglets eyes, which had 180°, 6mm diameter corneal trephnation perforating cuts.Soldering was done on some of the cuts at a set temperature of 65°C, with adjuvant 47% albumin solder, and standard suturing was done on other cuts, as control.Macroscopic and histologic evaluation was then carried out. Results: On macroscopic examination, the corneas were centrally clear, with corneal neovascularisation only around the sutures.Histologic examination of piglets corneas one week, one month, two months and five months after soldering revealed stromal lamellae which were organized with a fewer inflammatory reaction, in contrast to marked inflammatory response in the suture controls. Conclusions: The laser soldering technology appears to be reliable for closure of large corneal perforating cuts, and may overcome some of the technical difficulties and disadvantages of conventional corneal suture technique.
Background and objectives: A feedback temperature controlled laser soldering system was used for bonding cut wounds on the skins of young and mature pigs. This is a step towards clinical implantation of this promising novel technique. Materials and methods: 47% bovine serum albumin (BSA) solder was applied onto cuts created in dorsally d epilated skin on the backs of pigs, weighing 8 -10Kg or 74Kg. A temperature fiberoptic CO2 laser system was used to monitor and control the temperature of a spot on the cut at a desired temperature. For given values of time and temperature, a 28 days follow up of the soldered scars was obtained and compared with standard suturing. Results: Optimal soldering temperature was found to be 65ºC. The tensile strength of laser-soldered cuts was measured after 3-28 days postoperatively and was found similar to that of sutured cuts. Macroscopic and microscopic studies showed better and faster wound healing of soldered scars compared with standard sutures. All soldered scars in the mature pig, demonstrated excellent healing with no signs of dehiscence. Conclusions: Temperature controlled laser soldering of cut wounds in pig skin offers several advantages over standard suturing techniques. This novel method should be tested clinically.
Laser soldering of tissues is based on the application of a biological solder on the approximated edges of a cut. Our goal was to use laser soldering for sealing cuts in skin under temperature feedback control and compare the results with ones obtained using standard sutures. Albumin solder was applied onto the approximated edges of cuts created in rabbit skin. A fiberoptic system was used to deliver the radiation of a CO2 laser, to heat a spot near the cut edges, and to monitor and control the temperature. Laser soldering was carried out, spot by spot.
This study was to determine the feasibility and reproducibility of laser welding of cornea with a CO2 laser system capable of real times infrared fiberoptic radiometric control of tissue temperature. A fiberoptic radiometric temperature control system for the CO2 10.6 micrometers laser was developed that enabled a real time nontactile temperature measurement of welding surface. The system was tested on the cornea in 40 in vitro bovine eyes, and also in 6 in vivo corneas of rabbit eyes. Welds performed at a set point temperature of 65 degree(s)C, with or without adjuvant 50% albumin solder. Leaking pressure, surgical time and histologic evaluation were determined for welding and for suturing controls of 6 mm central corneal perforating cuts.
Background and objectives: Laser soldering of tissues is based on the application of a biological solder on the approximated edges of a cut. Our goal was to use laser soldering for sealing cuts in skin under temperature feedback control and compare the results with ones obtained using standard sutures. Materials and methods: Albumin solder was applied onto the approximated edges of cuts created in rat skin. A fiberoptic system was used to deliver the radiation of a CO2 laser, to heat a spot near the cut edges, and to control the temperature. Laser soldering was carried out, spot by spot, where the temperature at each spot was kept at 65-70 degree(s)C for 10 seconds. Results: The tensile strength of laser-soldered cuts was measured after 3-28 days postoperatively and was found comparable to that of sutured cuts. Histopathological studies showed no thermal damage and less inflammatory reaction than that caused by standard sutures. Conclusions: Temperature controlled laser soldering of cuts in rat skin gave strong bonding. The cosmetic and histological results were very good, in comparison to those of standard sutures.
The promising clinical potential for laser welding of tissues has generated a growing interest in this field. As improved laser welding system was constructed in this work. It was based on IR transmitting AgClBr fibers for laser power delivery and for temperature control. The fiberoptic system was used to transmit CO2 laser power for tissue heating and for non contact (radiometric) temperature monitoring and control. Bladder opening (cystotomy) was performed in 38 rats and 33 of the animals underwent laser welding. In 5 rats (control group) the bladder wound was closed with one layer continuous 6-0 dexon sutures. The rats were sacrificed on days 2, 10 and 30 for histological study. The temperature control of the upper tissue surface was set at 70 plus or minus 5 degrees Celsius. Bladder closure using laser welding was successful in 31/33 (94%) of the animals. The quality of the weld was examined immediately after the operation, revealing a water tight closure of the bladder wall. The histological examination showed an excellent welding and healing of the tissue. These results demonstrate the potential of temperature controlled CO2 laser welding.
CO2 lasers are among the most important lasers used for medical applications such as laser surgery. This laser is used mainly for tissue cutting and tissue removal, exploiting the high power of this laser systems and the high absorption of the biological tissue at this laser wavelength. Our research continues earlier studies conducted at the Tel Aviv University since 1987 that come out with a theoretical model used for simulating tissue irradiated with a CO2 laser beam. When examining the previous studies on laser ablation we have found that the important mechanism of steam pressure ablation was neglected. Therefore in our work we added steam pressure ablation into the model and studied the effects of this new mechanism on the tissue irradiated with a CO2 laser. The simulations results reveal that top-hat beam profile (uniformly distributed intensity) produces less thermal damage and its ablation efficiency is higher compared with standard Gaussian beam profile. We saw that the efficiency of the steam pressure ablation process is considerably higher than the purely thermal ablation process. We also noticed that the layers underneath the tissue surface are responsible for the pressure ablation.
3D finite difference computerized model was developed to simulate the thermal behavior of biological tissue irradiated with a CO2 laser beam. The model uses standard thermal processes and in addition takes into consideration water evaporation and the corresponding changes in the thermal properties of the tissue. The results contain a temperature and biological damage map of the irradiated tissue. Experimental results of test made on Lucite irradiated with CO2 laser fit very well the theoretical predictions. The model was then used for simulations of tissue welding and the results indicate that an improved method could be used for CO2 laser welding.
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