Effects of different contact laser scalpels on skin and subcutaneous fat

Laser-induced cavitation in plasmonic nanoparticle solutions: A comparative study between gold and titanium nitride

In this work, we present an extensive comparative study between novel titanium nitride nanoparticles (TiN NPs) and commercial gold nanorods (GNR), both dispersed in water and exposed to a pulsed laser-induced cavitation process. The optical density, shockwave emission, and bubble formation of these solutions were investigated using shadowgraphy, spatial transmittance modulation, and acoustic measurements. TiN nanoparticle solutions exhibited high stability undser a periodic nanosecond pulsed-laser irradiation, making these nanomaterials promising agents for high-power applications. In addition, they demonstrated a stronger nonlinear absorption compared to the GNR solutions, and plasma formation at lower laser energies. This study advances our understanding of the optical properties of TiN and discusses significant differences compared to gold, with important implications for future applications of this material in water treatment, nonlinear signal converting, and laser-induced cavitation for medical implementations, among others.

Use of carbon dioxide laser in oral soft tissue procedures

Lasers have been introduced in dentistry as an alternative to conventional knife surgery. The advantage to the operator includes a clean dry field that enhances visibility and reduces the procedure time. The patient benefits by minimal postoperative pain and swelling. The paper discusses use of carbon dioxide laser in five conditions commonly encountered in oral cavity.

Lasers in surgical periodontics and oral medicine

Surgical lasers rapidly are becoming part of the periodontal armamentarium. This article discusses the different lasers that are suitable for use on the soft tissues of the periodontium. Various laser-assisted periodontal surgical procedures and laser treatment of diseases of the oral mucosa are discussed.

Lasers in periodontics

Publicity about the use of lasers in dentistry has generated considerable interest in both professional and lay audiences. The purpose of this report is to provide information for members of the dental profession about the current and potential application of laser technology to periodontal practice. This report was prepared by the Research, Science and Therapy Committee of the American Academy of Periodontology.

Degradation-induced transmission losses in silica optical fibers

BACKGROUND AND OBJECTIVE

The interaction of surgical optical fibers with tissue has been studied. STUDY DESIGN/METHODS AND MATERIALS: Fibers (600 microns) were lased in chicken and beef tissue using a Nd:YAG laser from 5 to 50 W in both cw and pulsed modes.

RESULTS

With longer lasing and higher power, larger transmission loss and degradation (burn-in) of the fiber tip, occurred. This degradation converts the Nd:YAG laser power to heat and leads to further energy loss. During contact lasing, tissue and blood adhere to the fiber tip surface limiting laser transmission, desiccating, and eventually destroying adhering tissues. Such tissue residues create high power densities and temperatures at the tip, which then cause a variety of degradation processes to be initiated.

CONCLUSION

"Burned-in" fibers do not photocoagulate; rather they incise tissue. With continued lasing, thermal shock, chemical, and mechanical breakdown of the fiber leads to failure of the fiber tip and the spalling of glass fragments into the tissue bed.

The versatile contact Nd:YAG laser in head and neck surgery: an in vivo and clinical analysis

OBJECTIVE

Lasers have been used in otolaryngology as a surgical instrument for more than 25 years, and the CO2 laser has emerged as the most widely employed surgical laser in use today. However, recent technological advances have made the Nd:YAG laser a challenger as an effective photothermal surgical tool.

STUDY DESIGN AND METHODS

This is a two-part study. Tissue injury and healing profiles after application of both the CO2 and Nd:YAG lasers are compared using an in vivo rat tongue model. A prospective clinical review based on the experience of 327 operative cases spanning a 7-year interval using the Nd:YAG laser, highlighting its various applications and associated complications, is detailed.

RESULTS

Comparable tissue and healing effects were noted with both lasers in the in vivo rat tongue model with no statistical differences. The clinical application of the laser showed wide versatility in the head and neck with a complication rate of 3%.

CONCLUSION

The Nd:YAG laser has proved equivalent in tissue damage and healing to the CO2 laser. The Nd:YAG laser has proved itself to be an excellent and perhaps superior laser for use in head and neck surgery.

Transendoscopic laser treatment of guttural pouch tympanites in eight foals

Guttural pouch tympanites was diagnosed in eight foals with respiratory stridor and tympanic swelling in the parotid region. Three foals were treated by transendoscopic neodymium:yttrium aluminum garnet (Nd:YAG) laser fenestration of the median septum between the guttural pouches. One foal died of pneumonia, and the other two foals recovered completely, although the fenestration later closed in one foal. Five foals were treated by creating a salpingopharyngeal fistula using transendoscopic laser irradiation; complete resolution of the tympanites occurred. Transendoscopic laser surgery in standing foals may be a reasonable alternative to conventional surgery and general anesthesia for correction of guttural pouch tympanites.

Treatment of perianal fistulas with ND:YAG laser--results in twenty cases

Excision of perianal fistulas using a 1.064 micron wavelength neodymium:yttrium aluminum garnet (ND:YAG) contact tipped laser with primary wound closure was used to treat 20 dogs with perianal fistulas. Overall, 19 of 20 (95%) dogs had resolution of fistulas after one or more ND:YAG treatments. The period of resolution ranged from 10 to 42 months with a mean of 22.9 months. Sixteen of 20 (80%) dogs had resolved fistulas after one laser excision. Three of the four recurrences underwent additional laser treatments with successful results. The total number of laser procedures ranged from one to three with a mean of 1.2 procedures. Postoperatively, anal tone as judged by digital rectal examination was reduced in about 60% of the cases, but clinical evidence of fecal incontinence only occurred in four of 20 cases. This was managed effectively with diet modification. The tendency toward loss of anal tone or fecal incontinence depended on the severity of preexisting anal stenosis. On a client survey, 19 of 20 owners believed that their animals experienced less pain during defecation after surgery and rated the results as excellent or good. The overall success rate using ND:YAG laser excision compared very favorably with previously reported studies of other methods of treatment for perianal fistulas in dogs.

Clinical uses of lasers in dermatology

The accessibility of the skin to examination and study has permitted dermatologists to play an extremely important role in defining the clinical usefulness and limitations of many laser systems as well as developing innovative concepts, techniques and devices that further improved the effectiveness of laser treatment. As new laser technology evolved over the years, dermatologists have also helped define the specificity of laser-tissue interaction and employed the newly developed laser technologies in innovative ways which further expanded the usefulness of these devices. One of the most important concepts to be developed by dermatologists--selective photothermolysis--has led to the creation of a series of laser systems which have provided numerous unique advantages in the management of many common vascular and pigmented conditions of the skin and mucous membranes, even in infants and children. The net result of these technologic advances has been the creation of new and effective treatment techniques which have been so profoundly superior to existing technology that they have been rapidly incorporated into the daily practice of most dermatologists.

Reduced in vivo local recurrence with contact neodymium: Yttrium-Aluminium-Garnet (Nd:YAG) laser scalpels

BACKGROUND AND OBJECTIVE

Local recurrence after surgical resection for breast cancer is a significant problem and is often not controlled by radiation or chemotherapy treatments. Local recurrence is thought to be, at least in part, due to residual disease, and/or due to the contamination of the surgical field during resection. STUDY DESIGN MATERIALS AND METHODS: To address this later concern, we defined a model system using the mouse mammary cell line, EMT6. Using this model system, we have directly compared the rate of local recurrence of two different surgical approaches. One approach employed the use of traditional surgical instruments, and the other used a comparatively new contact Nd:YAG laser system. Tumor-bearing animals (242) were randomized into three groups. One group consisted of 50 animals that were not treated; 103 animals were randomized into a treatment group that received surgical resection using traditional instruments; 89 animals were resected using the contact laser system. In both surgical procedures, an intentional incision was made through the tumor and then through an uninvolved portion of the surgical field in an attempt to "seed" the incision using the contaminated surgical instrument.

RESULTS

Twenty-one of the 103 scalpel-treated animals had local recurrence; only seven of the 89 laser-treated animal had local recurrence. The untreated group died of disease within 8 weeks. In the treatment groups, recurrences were palpable within 1 week. At the time of death for all groups, no metastatic lesions were noted.

CONCLUSION

These findings support the conclusions that the EMT6 cell line is a useful model to study local recurrence and that contact laser surgery provides about a 50% improvement in the control of local disease in vivo (P < 0.05).

Monopolar electrosurgery and Nd:YAG Contact Laser in laparoscopic intestinal surgery

In a prospective randomized study using a canine model, we compared the use of monopolar electrosurgery (EC) (n = 23) and the Nd:YAG Contact Laser (CL) (n = 21) on intra- and postoperative morbidity in laparoscopic large-bowel resection. In EC, cutting was performed with scissors and coagulation was performed with electrosurgery. In CL, cutting and coagulation were carried out with the Nd:YAG Contact Laser. Laparoscopic oncologic right colectomy with intraperitoneal ileocolic stapled anastomosis was performed in all dogs. Intraoperative smoke development, difficulty of dissection, hemostasis, and postoperative adhesions were judged using a five-point score. Two weeks after surgery, all dogs were sacrificed and zoopsy was carried out. Three dogs died postoperatively from pneumonia and one from an anastomotic leak. There were no other postoperative complications. Operative time was 135 min (range 105-180) in the CL group and 145 min (range 60-210) in the EC group. Intraoperative smoke development, difficulty of dissection, and postoperative amount of adhesions were not different between groups (P > 0.05). Hemostasis in the CL group (median score of 1, range 1-2) was significantly better (P = 0.01) than in the EC group (median score of 2, range 1-5). Scissors and electrosurgery as well as Nd:YAG Contact Laser can be used successfully in intestinal laparoscopic surgery. Although the use of the Contact Laser did not cause less postoperative morbidity than the conventional method, there was significantly better hemostasis using the Nd: YAG Contact Laser.

A new method for the detection of viable cells in tissue sections using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT): an application in the assessment of tissue damage by surgical instruments

This report describes a new method using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to visualize live viable tissue at the microscopic level. The visualization of the MTT stained tissue provides a metabolic assessment of tissue damage, and can be utilized as an extension of conventional hematoxylin-eosin (H & E) staining. In this report, several tissues were studied with MTT and H & E staining after incisions had been made by a variety of surgical dissecting instruments. A marked improvement in the detection of tissue damage was seen using MTT, regardless of how the damage was caused, i.e., physical, heat, or photon energy. In addition, a distinct zone of damage not noted on conventionally prepared and stained tissues is readily apparent. Thus MTT staining will have utility in both clinical and research studies, concerned with assessing the viability of tissues.

Keloids and hypertrophic scars

BACKGROUND

Keloids and hypertrophic scars are benign fibrous growths which usually occur after trauma in predisposed individuals. Their etiology, clinical manifestations and treatment are diverse.

OBJECTIVE

The purpose of this article is to review the pertinent literature concerning keloids and hypertrophic scars as well as present my own perspective on the subject. It is my hope that the information contained herein will help both the dermatologist and dermatologic surgeon better understand and manage these vexing lesions.

METHODS

Medline literature search as well as original material.

RESULTS

There is no one right way to treat all keloids and hypertrophic scars. Treatment results have been variable.

CONCLUSION

The management of keloids and hypertrophic scars can be difficult and frustrating for both patient and physician. A better understanding of keloid pathogenesis may lead to improved therapies by which keloid growth and regrowth may be obviated.

Reduced tumor cell transfer with contact neodymium-yttrium-aluminium garnett laser scalpels

The local recurrence of tumor growth after surgery is thought, in part, to be a consequence of seeding of tumor cells from the primary lesion. This study was directed at determining if the contact Nd:YAG laser provides any advantage over the use of traditional scalpel dissection for tumor resection. Five human tumor tissue culture cell lines were studied in this report. They included MCF-7 (breast), HeLa (cervical), SW-780 (bladder), HT29 (colon), and A549 (lung). Using a scalpel blade or contact laser scalpel (with or without laser energy), the ability to transfer viable cells from dense cell stocks to new tissue culture wells was tested. Using the A549 cell line, the extent that these instruments were able to "seed" tumor cells was also assessed in a soft agar, in vitro, "incision" model. Results from these studies suggest that the contact laser scalpel has a significantly lower potential to transmit tumor cells, when compared to traditional scalpel blades.

Width of thermal damage after using the YAG contact laser for cutting biological tissue: animal experimental investigation

At the University Women's Clinic in Kiel, the YAG contact laser has been used as a cutting instrument in pelviscopic operations since 1987. When the laser cuts, it produces only a scant amount of mechanical trauma. The determining factor is the amount of thermal damage produced along the wound margins and in direct neighboring tissue. The extent of the tissue change seen in the uterus and liver parenchyma of rats and the striated muscle of rabbits after application of the YAG contact laser was demonstrated using various staining techniques and stains. Liver parenchyma proved to be the most sensitive to thermal damage. In the uterine horn, enzyme-histochemical ATPase and alkaline phosphatase demonstrations showed a significantly wider zone of thermal damage after laser incision than did hematoxylin-eosin and Goldner staining techniques. A good understanding of the extent of thermal damage is essential for atraumatic pelviscopic operations using the YAG contact laser and also for the preventing of complications.

Ray tracing of optically modified fiber tips. 2: laser scalpels

The spatial irradiance distribution of tapered fibers and tapered rods used as scalpels in laser surgery has been calculated by ray tracing. The results were compared to measurements in air and in water. The beam profiles of laser scalpels were conically shaped at discrete angles related to the number of reflections within the scalpel. Light started to leak radially out of the scalpel before it reached the tip slightly suppressing the increase in fluence rate toward the tip. For effective tissue cutting, the scalpel tip may be shortened to optimize the irradiance increase in combination with radial energy leakage to obtain controlled hemostatic coagulation.

YAG laser resection of complicated hemangiomas of the hand and upper extremity

Complicated hemangiomas of the hand or upper extremity have been resected in eight patients with use of the YAG laser with sapphire scalpels. This laser allows excellent hemostasis and precise surgery, thus allowing resection of complicated problems. Many of the patients have had preoperative arteriography with selective embolization, which has aided in hemostasis. Almost complete but subtotal resection of hemangioma was possible in four of the eight patients with well localized lesions. Three patients had only partial resections of hemangiomas and one lesion was considered unresectable.

Combination treatment for massive cavernous hemangioma of the face: YAG laser photocoagulation plus direct steroid injection followed by YAG laser resection with sapphire scalpel tips, aided by superselective embolization

A massive cavernous hemangioma of the face in an 11 month old child has been successfully resected utilizing a combination of laser and non-laser techniques. The hemangioma was initially treated twice with YAG laser photocoagulation plus direct injection of steroids. This treatment promptly stopped the rapid growth and induced blanching as well as a 25% shrinkage with each treatment. Arteriogram with superselective embolization produced a further shrinkage of the hemangioma. Finally, the contact YAG laser with sapphire scalpel tips was utilized for complete and cosmetically satisfactory hemangioma resection. The treatment of a massive cavernous hemangioma by a combination of modalities is discussed.

Comparison of surgical lasers and conventional methods in skin incisions

Steel scalpel, electrocautery, CO2 laser used in a continuous wave mode (CW) and rapid superpulse mode (RSP), and contact Nd: YAG laser were tested on pig skin incisions. Speed of incision and histological changes near the wounds were examined. Light microscopical observations were made on postoperative day 0 using standard Van Gieson stain. Width of the scar on postoperative day 14 was also measured. Steel scalpel produced the least pathological changes in the skin, followed by RSP. Electrocautery did not differ significantly from the CO2 lasers in this respect on postoperative day 0. The damage was larger after contact Nd:YAG laser. The situation was essentially similar on postoperative day 14. The width of the scar was narrowest after steel scalpel and widest after contact Nd:YAG laser (p less than 0.01; Nd:YAG vs. other methods). Electrocautery and the two CO2 lasers produced equal scarring. However, electrocautery was significantly faster than any of the lasers (p less than 0.001).

Lactate dehydrogenase in laser incisions: a comparative analysis of skin wounds made with steel scalpel, electrocautery, superpulse--continuous wave mode carbon-dioxide lasers, and contact Nd:YAG laser

A histochemical method for demonstrating lactate dehydrogenase activity was used in addition to standard Van Gieson stain to study early alterations near wounds made in pig skin by steel scalpel, electrocautery, two modes of CO2 laser (the rapid super-pulse mode and the continuous wave mode), and contact Nd:YAG laser. The enzyme-free zone near the wounds made using the thermal knives appeared to be twice as wide as the necrotic zone observed with Van Gieson stain. In polarized light, the enzyme-free area showed two zones of equal width with respect to birefringence of collagen fibers. The zone lacking birefringence correlated well with that observed with Van Gieson stain. The birefringent zone represented functionally damaged tissue with more or less normal structures by light microscopy. The damage to adjacent tissue caused with the thermal knives seems to be considerably larger than has usually been reported.