Effects of different contact laser scalpels on skin and subcutaneous fat

The tissue effects of different Nd:YAG contact laser scalpels on pig skin and subcutaneous fat were studied using various power settings. Three different laser scalpels were tested: 0.2 mm nonfrosted (LR2), 0.6 mm nonfrosted (LR6), and 1.0 mm frosted (LRP10), using 3 different power settings (8 W, 14 W, 18 W). The tissue effects of a steel scalpel were used as reference. Incisions on pig loin (40/pig) were made at randomized sites. Specimens were taken at postoperative days 0 and 14. The depth of tissue damage was measured using a light microscope. The amount of time required for making each incision was recorded. Significant differences between the LR2 and the LR6 were observed in the skin at 2 weeks (P less than .05) at all power settings used, indicating superiority of the smaller scalpel for use in skin incisions. The LRP10 did not cause more tissue damage than did the LR6 in any of the power settings used. In subcutaneous fat the smallest scalpel (LR2) caused significantly less tissue damage evident at 2 weeks postoperatively (P less than .05) than did the other two laser scalpels, whereas the effects of the different power settings were minor. The incision time in skin decreased by more than 50% when the power was increased from 8 W to 18 W for all laser scalpels studied.     

Treatment of benign, semimalignant, and malignant skin tumors with the Nd:YAG laser

Reported are first experiences with Nd:YAG laser treatment of benign, semimalignant, and malignant skin tumors in 90 patients. Treated lesions included condylomata acuminata, basal cell carcinomas, solar keratosis, squamous cell carcinomas, and secondary malignant skin tumors. First clinical and histological results are promising, but long-term follow-up is required to judge the definite efficacy of this therapeutical modality.     

Denudation of the entire mucosa of the canine urinary bladder using the neodymium:YAG laser with the MTR 1.5 contact probe

Although the procedure of mucosal stripping or denudation of the urinary bladder was developed over 25 years ago to treat the potentially neoplastic mucosa in patients with low-grade superficial transitional cell carcinoma of the bladder, the procedure was abandoned because of serious complications, including short-term bladder hemorrhage and urinary extravasation and long-term severe bladder contracture, ureteral reflux, and hydronephrosis. In this study, we used the neodymium:YAG laser with the MTR 1.5 contact probe to denude the entire mucosa of the canine urinary bladder. Evaluation of our results showed that mucosal denudation by this technique can be performed simply and safely without complications. Specifically, we encountered no significant bladder hemorrhage, urinary extravasation, bladder contracture, ureteral reflux, or hydronephrosis. We believe that the denudation procedure may be useful as a surgical means of treating the entire bladder mucosa in patients with proliferative epithelial lesions of the bladder including multifocal carcinoma in situ.     

Comparison of thermal tissue effects induced by contact application of fiber guided laser systems

BACKGROUND AND OBJECTIVES: Laser light of various wavelengths is being used for surgical procedures in otolaryngology. Apart from well-known fiber guided laser systems such as Nd:YAG- and Ho:YAG-lasers, newly developed diode-laser systems of different wavelengths have recently become popular in surgery. In order to compare the effects of fiber guided laser light with respect to their induced tissue effects, these laser systems have been studied and compared under reproducible test conditions. STUDY DESIGN/MATERIALS AND METHODS: The laser fibers of four common medical laser systems (Ho:YAG- (lambda = 2,080 nm), Nd:YAG- (lambda = 1,064 nm), and diode-laser (lambda = 830 and 940 nm)) were fixed to a computer controlled stepper motor. The laser light was applied in contact mode onto ex vivo muscle tissue, using identical power settings and a reproducible application procedure (application velocity, application angle) under constant conditions (temperature of tissue and volume). The size of the thermal effects on the tissue (e.g., coagulation, ablation, and carbonization zones) were measured and photographed via optical microscopy. RESULTS: Depending on the laser wavelength used, the experimental results proved different degrees of tissue responses. Nd:YAG- and diode-lasers provided for only low coagulation effects in the depth of the tissue, but produced severe carbonization at the surface. Ho:YAG-laser light revealed the highest ablation capabilities of the lasers investigated in addition to large coagulation zones which were of larger extent than those produced by Nd:YAG- and diode-laser light. CONCLUSIONS: Contact treatment by Ho:YAG-laser light might provide for a precise and effective tissue reduction in a bloodless manner because of its high ablation and coagulation capabilities, especially if large volumes are treated and structures beneath are non-critical. In comparison, Nd:YAG- and diode-laser treatment in contact application showed low thermal tissue effects (i.e., coagulation) in the depth, resulting from a high power loss caused by the development of large carbonization zones at the surface of the tissue. Therefore, the degree of blood-perfusion and the capability of vessel-closure induced by these lasers should be taken into account. The presented investigation also revealed that in contact mode, the tested laser systems produced tissue effects, which were highly different from those already described for applications in non-contact mode. Physicians who are performing laser treatments in close boundaries must be aware that changing from non-contact to contact mode in laser application greatly influences the resulting tissue effects.     

Vasal anastomoses in dogs using contact neodymium: Yttrium aluminum garnet (Nd:YAG) laser

The purpose of this study is to evaluate the contact NdrYAG laser system for vasal anatomosis in the animal model. Eighteen mongrel dogs were used. In this study, two major groups—control and laser—were defined. In the control group, vas anastomoses were performed with conventional microsurgical technique in six dogs. In the laser group, we performed contact laser assisted vas anatomosis (CLAVA) in 12 dogs by means of a contact Nd: YAG laser with synthetic sapphire probe (ERP4), emitted 2.0 sec pulse duration of minimum 1 watt to maximum 10 watts power. The time needed for completion of the vasal anatomosis in CLAVA group was 2–3 min; in the control group, ～ 25 min. The patency rate did not differ in these two groups; however, microscopic sperm granuloma formation was 16.7% (2/12) in the control group but 0%(0/12) in the CLAVA group. In conclusion, CLAVA is a fast and simple technique for vasal anatomosis and there were no significant complications, sperm granuloma, or even significant swelling or hematoma in any animal in this experiment. © 1994 Wiley-Liss, Inc.     

Nd:YAG激光与强脉冲光非剥脱性嫩肤的动物实验

Objective To observe the histological change of different waves in treating SD rats of the long-pulse 1064nm Nd:YAG laser and the 560～1200 nm intense pulse light,in order to provide the theory bases of non-ablative rejuvenation.Methods Two waves were used on experimental mice.The dermic thickness and the expression of collagen typesⅠand Ⅲwere detected by HE stain and immunohistochemical methods. Semiquantitative analysis was used to determine the mean of absorbance.Results Thedermal thicknesses and the mean of absorbance of collagen typesⅠandⅢin two different waves were higher than those in common control groups(P＜0.05).The effect of Nd:YAG laser groups were higher than IPL groups(P＜0.05).The expression of collagen typeⅠwas higher than that of collagen type Ⅲ(P＜0.001).Conclusion After Nd:YAG laser or IPL irradiation,the dermal thickness and collagen typesⅠandⅢof SD rats are increased.The effects of Nd:YAG laser are better than those of 560～1 200 nm IPL.The expression of collagen type Ⅲ is obviously more than that of collagen typeⅠin the early,whereas the expression of collagen typeⅠis obviously more than that of collagen type Ⅲin the later.It proves that the mechanism of dermal remodeling of non-ablative skin rejuvenation is mainly correlation with raising range and time of collagen typeⅠ.     

Effect of tissue pressure on contact laser insults.

The effect of variations in tissue pressure transmitted through contact laser probes during tissue ablation has been investigated. Weights of 10 and 50 g were transmitted through the tip of the probes onto the gastric and colorectal wall. At all laser energies the depth of tissue vaporization was significantly greater at the higher tissue pressure with perforation of the viscus occurring at laser energies above 10 J. The lateral zones of thermal tissue necrosis were not influenced by tissue pressure. Deformation of the wall of the viscus under the pressure of the probe was identified as a sign of excessive tissue pressure likely to result in perforation of any tissue of similar thickness to the normal gastric or colorectal wall.     

Induced hyperthermia in brain tissue: Comparison between contact Nd:YAG laser system and automatically controlled high frequency current

Summary Concerning hyperthermia treatment, knowledge of time-temperature and of temperature distributions within tumour volumes is essential in order to obtain the maximal therapeutic effect. New techniques are developed to overcome these difficulties. Two different heat sources, the contact Nd:YAG laser system and the automatically controlled high frequency current are investigated. In a defined volume of 1cm³, the laser system reaches 45 °C after 1.8 s exposure with 15 W output power. The high frequency current reaches 45 °C with 48 s exposition with 18.75 W output current. Both heat sources present an exponential decrease of the temperature profile depending on the distance and prove efficient for inducing anti-tumoural hyperthermia. The tissue heat clearance is compensated for by intermittent laser and high frequency current application.     

Effective outpatient treatment of Kaposi's sarcoma of the urethral meatus using the neodymium:YAG laser

An unusual presentation of acquired immunodeficiency syndrome (AIDS)--a case of Kaposi's sarcoma involving the glans penis and fossa navicularis--was treated palliatively with neodymium:YAG (Nd:YAG) laser photoablation. A single outpatient treatment removed the two lesions and restored the patient's ability to void normally. The Nd:YAG laser proved extremely useful, providing effective outpatient therapy with minimal morbidity and excellent local results.     

Laser photoirradiation of the canine ureteral orifice: comparison between contact and noncontact techniques

We studied the long-term effects of Nd:YAG laser photoirradiation in 17 canine ureteral orifices, comparing results of the contact and noncontact (free-fiber) techniques. The noncontact technique damaged four of eight ureters, causing ureteral obstruction with significant hydronephrosis in three and reflux in one. The amount of energy used correlated with the subsequent appearance of ureteral obstruction; obstruction developed in both cases when 3,000 and 3,300 joules were used but in only one of five cases when less than 2,300 joules were used. In contrast, the contact technique, using 350-800 joules, caused no hydronephrosis and only one case of reflux. Since these animal studies clearly document that the Nd:YAG laser may significantly damage the ureter, particularly when the noncontact technique is used, we recommend that the surgeon consider the contact technique to reduce the risk of ureteral damage and use the smallest amount of energy required for adequate tumor eradication when treating tumors in or near the ureteral orifice.     

Endoscopic laser therapy of the watermelon stomach.

Endoscopic laser therapy has been used in the treatment of vascular lesions throughout the gastrointestinal tract. The "watermelon stomach" is a pattern of vascular ectasia in the gastric antrum that results in chronic gastrointestinal blood loss and iron deficiency anemia. We have treated 7 transfusion dependent patients with a watermelon stomach using endoscopic laser therapy. Four of these patients were treated with the argon laser and 3 with the Nd:YAG laser. Patient age and prior transfusion requirements were similar in both groups. The mean number of treatments to obliterate vascular lesions and eliminate the need for transfusions was 5.75 +/- 0.89 (SEM) for the argon laser and 2.33 +/- 0.27 for the Nd:YAG laser (P < 0.05). Lesions recurred and required retreatment in 1 patient treated with the Nd:YAG laser and 3 patients treated with the argon laser (mean follow-up of 35 months). We conclude that endoscopic laser therapy with either the argon or Nd:YAG laser is an effective treatment modality for antral vascular ectasia (watermelon stomach). The Nd:YAG laser requires fewer treatment sessions than the argon laser to obliterate the lesions without increased risk of complications.     

Nd：YAG激光与强脉冲光非剥脱性嫩肤的动物实验

目的探讨Nd：YAG激光长脉宽波长1064nm与强脉冲光（intense pulsed light,IPL）波长560～1200nm两种波长照射SD大鼠皮肤后组织学变化趋势,为临床非剥脱性光嫩肤的科学治疗提供理论依据。方法应用两种波长照射SD大鼠背部脱毛皮肤,通过HE染色和免疫组织化学染色方法检测真皮厚度、Ⅰ型和Ⅲ型胶原蛋白的表达,并测定平均吸光度值进行半定量分析。结果两种波长照射后真皮厚度、Ⅰ型及Ⅲ型胶原蛋白平均吸光度值均高于正常对照组（P〈0．05）,激光组均又高于IPL组（P〈O．05）,Ⅰ型胶原蛋白平均吸光度增加值均高于Ⅲ型胶原蛋白（P〈0．001）。结论两种波长均可使SD大鼠真皮厚度和Ⅰ型、Ⅲ型胶原蛋白增加,激光组优于IPL组。Ⅲ型胶原蛋白在照射早期增加幅度较高,而Ⅰ型胶原蛋白在照射后期增加幅度较高,提示非剥脱性光嫩肤真皮重塑机制可能与Ⅰ型胶原蛋白增加的时间和量有关。     

Q-开关Nd:YAG激光治疗外源性皮肤色素性病变124例

目的：观察Q-开关Nd：YAG激光治疗外源性皮肤色素性病变的临床效果。方法：用Q-开关Nd：YAG激光1064nm波长治疗黑色、灰色或蓝色皮肤色素性病变；532nm波长治疗红色色素性病变，共计124例。结果：此方法可明显去除外源性皮肤色素性病变，效果好、无瘢痕产生，但需多次治疗。结论：Q-开关Nd：YAG激光治疗外源性皮肤色素性病变安全有效。     

Computer-assisted evaluation of microleakage after apical resection with laser and conventional techniques

The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces after apicoectomy with conventional techniques and laser beam. Sixty single-rooted extracted teeth were selected for the study. The crowns were resected below the cemento-enamel junction. Then, these teeth were treated endodontically and filled with gutta-percha using AH-26 root canal sealer. The teeth were randomly divided into four groups of 15 teeth in each. The roots were resected perpendicular to its long axis 3 mm from the apex using Er: yttrium–aluminium–garnet (YAG) laser irradiation in groups 1 and 2, and the resected root surfaces were lased with Nd:YAG laser in group 2. The apexes were resected by a high-speed handpiece in groups 3 and 4, and the resected root surfaces were lased with Nd:YAG laser in group 4. Ten teeth in each group were used for leakage studies, and the other five teeth were used for scanning electron microscopic examinations. Seven sections were obtained from each root to assess the microleakage, and the sections were analyzed in a computer-assisted manner. No statistically significant differences were observed between the leakage percentage of groups 1 and 3 and groups 2 and 4 (p > 0.05). Morphological differences were observed between apical dentin surfaces resected with conventional techniques and laser beam.     

Transscleral cyclophotocoagulation using a contact laser probe: a histologic and clinical study in rabbits

Transscleral photocoagulation of the ciliary body was achieved in pigmented rabbits using a sapphire probe delivery system coupled to a commercial surgical continuous-wave Nd:YAG laser. This contact technique was found to be effective in reducing intraocular pressure (IOP); greater treatment energies were associated with a more prolonged reduction in IOP, and also correlated with a greater degree of histologic damage to the ciliary body. Treatment energies of 0.8-1.0 Joules produced substantial disruption of the ciliary body. This technique is easy to learn and offers ease in control and placement of the coagulation spots.     

Clinical application of the Nd:YAG laser bipolar dissector in intra-abdominal surgery.

A laser bipolar dissector (LBD) using a 1064 nm Nd:YAG laser energy source that provides hemostatic dissection using low-powered laser energy (15-25 W) has been developed. Clinical applications have included a partial hepatectomy (n = 5), a cholecystectomy (n = 4), an appendectomy, lymphnode dissection, and division of adhesions. The LBD was effective in resection of noncirrhotic liver and reduced the number of ligations required. There were no direct complications related to using the LBD. Operative time and blood loss were difficult to compare to conventional methods. The LBD may have applications for partial hepatectomies and other intra-abdominal operations.     

Computer analysis of laser dosimetry data: a method of accurate energy density delivery

In the past, utilization of the laser in medicine has been limited by the lack of accurate quantification of the energies delivered to the tissue. Data obtained in the course of this investigation have demonstrated the relationships which exist between the energy delivered to the tissue and the optical system composed of the fiber and focusing lens. A continuous-wave multimode Nd:YAG laser (1,064 nm) was used in these experiments. Utilizing the beam scan technique previously described, we recorded over 100 beam profiles at various distances from the handpiece (fiber optic and lens). Computer analysis of our data established the mathematical correlation between the surface area of the irradiated spot and the distance of the handpiece to the target, thus allowing us to predict the surface area of the irradiated spot to any desired distance. By duplicating our methods with his particular optical system, the clinician or any laser user has the capacity to determine the energy delivered to the tissue (J/cm2) by knowing the power of the laser (watts), the time of exposure (seconds), and the distance of the handpiece to the treatment site (centimeters).     

Preliminary study of the Nd:YAG laser in canine partial nephrectomy

Partial nephrectomy is effective in the treatment of segmental renal disease but hemostasis remains a challenge. In this preliminary investigation the Nd:YAG laser was used alone or as an adjunct to the scalpel in partial nephrectomies to determine if hemostasis could be improved. A technique of 100-W laser transection with occlusion of the renal artery was effective for partial nephrectomy and achieved complete hemostasis. Conditions of patent renal artery flow or renal cooling were associated with a reduction in necrosis depth with 100-W laser partial nephrectomies. All techniques were compatible with survival over the 5-day study period.