Tissue Vaporization Research Articles

Ablative laser resurfacing: high-energy pulsed carbon dioxide and erbium:yttrium-aluminum-garnet

The development of the short-pulsed high-energy carbon dioxide laser in the mid 1990's led to the emergence of laser skin resurfacing. Used in the continuous mode, the CO 2 laser can cut and coagulate simultaneously. Used in the pulsed mode, the CO 2 laser is a powerful tool for epidermal ablation in many different contexts both therapeutic and cosmetic. Both the CO 2 and Erbium YAG lasers emit light in the infrared spectrum. Energy is preferentially absorbed by intracellular water creating rapid heating and vaporization of tissue. Because of the wavelength of the Er:YAG laser (2940nm) more closely approximates the absorption peak of water (3000nm) the target chromophore than the CO 2 laser (10,600nm) nearly all of the energy is absorbed in the epidermis and papillary dermis yielding superficial ablation and less underlying thermal damage. The advantages, disadvantages, and applications of each type of laser resurfacing will be discussed. Despite proven efficacy, the public acceptance of laser resurfacing has declined with the emergence of new laser systems that cause dermal remodeling without ablating the overlying epidermis dramatically reducing recovery time. In the absence of blinded comparison studies, it remains unclear whether the clinical results of the newer ‘nonablative' laser systems compare with their ablative predecessors.

Acromegaly presented as a cause of laryngeal dyspnea

Acromegalic patients can develop obstructive sleep apnea syndrome or upper airflow obstruction. The development of dyspnea is unusual and the fixation of both vocal cords is exceptional. We report the case of a patient with bilateral vocal cord paralysis. Fiberoptic laryngoscopy and computed tomography (CT) of the neck showed a supra-glottic stenosis due to a swelling of the soft tissue. A tracheostomy was first performed. Thereafter, micro-laryngoscopy using laser vaporisation of the supra-glottic soft tissue was attempted but failed to remove the tracheostomy canula. Finally, blood tests and cerebral MRI revealed an acromegaly. The patient underwent a trans-sphenoidal resection of the pituitary adenoma. Fifteen months later, fiberoptic laryngoscopy showed bilateral restoration of vocal cord mobility and the tracheostomy canula was successfully removed after 18 months. Vocal cord fixation is probably due to hypopharyngeal and laryngeal soft tissue swelling and can be reversible after successful treatment of the adenoma.

MP-21.12: A prospective randomised study between transurethral vaporisation using plasmakinetic energy and transurethral resection of prostate: five-year results

A prospective randomised study was conducted to evaluate the safety and efficacy of Plasmakinetic™ energy (Gyrus electrosurgical system) that produces vaporisation of tissue immersed in isotonic saline against standard transurethral resection of the prostate in the treatment of benign prostatic hyperplasia.

Electromagnetic field system for transsphenoidal surgery on recurrent pituitary lesions—technical note

Background Post operative scar tissue makes transsphenoidal surgery for recurrent pituitary lesions very difficult. However, with the use of a new cautery system, known as the EMF system, we were able to perform the surgical procedures with relative ease. In this article, we report the advantages and clinical applications of this new instrument in transnasal reoperation. Methods The EMF system generates a high frequency current of 13.56 MHz that is focused on the target. This enables it to coagulate, cut, and vaporize tissue in a pinpoint fashion. The bayonet and pencil-type hand pieces of the EMF system are slim, and the tips of the probe are flexible. This enables the surgeon to easily reach deep narrow spaces. We have used the EMF system for transsphenoidal surgery on recurrent pituitary lesions in 18 patients. The system was used to cut and vaporize scar tissue and vaporize firm and fibrotic tumor tissue. Results During surgery, the system could easily cut and vaporize scarred tissues in the nasal cavity, the sphenoid sinus, and the sella, without damage to the surrounding tissue. In addition, in 3 patients who had extremely fibrotic and firm tumors, we were able to easily vaporize the tumor with safety. Conclusions The EMF system enables the surgeon to cut and vaporize tissue with ease and with minimal injury to the surrounding structures. It was particularly valuable in the resection of firm tumors. It may also shorten the operating time because of quick vaporization of the firm tissue.

Radiofrequency Ablation and Photodynamic Therapies: What Are the In-Vivo EUS and Histologic Correlates?

Tissue vaporization or coagulation from PDT and balloon-based radiofrequency (RF) ablation has been gaining acceptance as a potential treatment for Barrett esophagus and local esophageal adenocarcinoma. However, there is a paucity of data regarding the extent of epithelial changes secondary to these forms of ablative therapy. Aim: To determine EUS and histologic changes in human esophageal epithelium subsequent to PDT and RF treatments. Methods: Prospective EUS examinations and systematic biopsies in four quadrants, each cm, and at set time intervals were performed following treatment of Barrett esophagus with PDT or RF. Energy was delivered at 200 J/cm for PDT, whereas the RF energy density was pre-set at 12 J/cm2. All patients were placed on PPI's. Results: 55 patients (51 men, 4 women), mean age 68 (38-81), underwent PDT or RF from 11-2003 to 12-2005. The length of Barrett segments ranged from 1 cm to 10 cm. Eleven patients had histologically proven and verified high grade and were treated with RF. A total of 44 EUS examinations with mechanical radial, electronic radial, electronic linear echoendoscopes and through-the-scope probes were performed in 6 PDT and 4 RF patients. Biopsies were obtained in 4 quadrants every cm with jumbo forceps. Post PDT changes affected the mucosa, submucosa, and muscularis propria with thickness up to 8 mm, which decreased to 3.4 mm @ month 19. RT changes included the muscularis propria with thickness of 4 mm @ month 9. One patient in each group developed adenocarcinoma at 8 and 9 months. The longest post ablative EUS follow-up was 19 months. Conclusions: Ablative therapy with PDT and RF can cause epithelial changes through the muscularis propria. The predominant alterations are seen as hypoechoic thickening of the mucosal and submucosal layers. The increased thickness lessens with time. EUS hypoechoic thickening of the mucosa, submucosa, and muscularis propria without endoscopically visible nodule/mass is likely non-malignant in this clinical setting.

Same-session KTP laser vaporization of large prostate and holmium laser treatment of bladder stones

Bladder stone formation is associated with benign prostatic hyperplasia and symptoms of bladder outlet obstruction. The potassium-titanyl phosphate (KTP) laser has recently been used in several studies for vaporization of benign prostatic tissue. We report a series of patients with large prostate volumes (> 150 cm3) who were successfully treated with same-session KTP laser vaporization of the prostate and holmium-YAG laser lithotripsy of bladder stones.

High-Powered Holmium-Laser Ablation: Comparison of Setting Effectiveness Using Tissue-Surrogate Model

The 100-W holmium laser, in conjunction with a sidefiring 550-microm fiber, can ablate prostate glands as large as 40 g to relieve lower urinary-tract symptoms. We evaluated the effect of various setting combinations on ablation efficiency using beef kidney as a tissue-surrogate model. Beef kidney specimens (mean weight 44.8 +/- 3.1 g) were secured in a cylinder, which was submerged in a water-filled tank through which a 27F resectoscope and 550-microm sidefiring fiber were positioned. Four energy/frequency combinations were tested, with each used to treat 10 kidney specimens. The difference between the mean pretreatment and post-treatment weights of each treatment group were compared statistically with Student's t-test. The largest mean weight difference after treatment (8.94 +/- 2.38 g) was achieved using 3.2 J and 25 Hz. This mass reduction was significantly greater than that of all other combinations except 2.5 J and 40 Hz. Use of the 3.2 J and 25 Hz setting combination resulted in the greatest amount of ablation in this tissue-surrogate model, suggesting that maximal energy settings may provide an advantage in tissue vaporization using the 100-W holmium laser. Clinical assessment must be performed to substantiate these findings.

Excimer laser ablation for valvular angioplasty in pulmonary atresia and intact ventricular septum

The prognosis for infants with pulmonary atresia and intact ventricular septum (PA/IVS) is poor and they present a major management challenge. Mechanical penetration of the atretic pulmonary valve is an applicable option for decompression of the right ventricle and optimization of left ventricular function. The utilization of laser energy for debulking and vaporization of the atretic valve tissue is a relevant approach due to the potential for controlled, precise mode of energy distribution. A 4-month-old female with PA/IVS whose failure to thrive was accompanied by critical hemodynamic abnormalities received successful percutaneous pulmonary valve plate ablation by a 0.9 mm pulsed-wave ultraviolet excimer laser catheter (308 nm wavelength, fluence 50 mJ/mm(2); 30 Hz). A "step-by-step" lasing technique was applied whereby the tip of the emitting laser catheter is advanced ahead of a guide wire that serves mainly as support for positioning of that catheter. Adequate penetration of the atretic tissue enabled introduction of balloon dilations resulting in patency of the atretic valve, decompression of the right ventricle, improved right and left ventricular hemodynamics, and oxygenation. To further investigate the effect of excimer laser energy on atretic valvular tissue this laser was applied in a specimen of heart from an infant who died because of PA/IVS. Histopathologic examination of the irradiated tissue revealed no laser-induced injury to the pulmonary valve. Thus, laser ablation and penetration of an atretic pulmonary valve is feasible and safe. The penetration of the atretic valve with the laser catheter enables subsequent introduction of various sizes balloon dilations. The application of available laser sources for treatment of congenital heart diseases is reviewed.

Surgical pearl: Removal of cosmetic lip-liner tattoo with the pulsed carbon dioxide laser

T he increased availability of cosmetic tattoo procedures has also led to an increase in the demand for cosmetic tattoo removal. Undesired appearance of the tattoo either shortly after its application or, after a change in color over time, are common reasons given by patients who request removal of their cosmetic tattoos. Traditionally, Qswitched lasers, such as the ruby, Nd:YAG, and alexandrite, are effective for black, green, red, orange, and purple colors.1,2 However, it is best to avoid using these lasers to remove tattoo pigments suspected of containing metallic oxides. Paradoxical darkening of the tattoo pigments may occur after treatment with any Q-switched lasers that can be permanent and disfiguring.3 The change in iron oxidation states from ferric to ferrous oxide is believed to be responsible for the darkening of the tattoo. Ferric oxide-containing pigments are often found in red, pink, and flesh-colored tattoos. A 44-year-old woman was dissatisfied with the appearance of her pinkish-red cosmetic lip-liner tattoo and requested removal. Cosmetic tattoos of this color typically contain iron oxide. Both the upper and lower lip margins had been outlined with tattoo ink 2 months earlier (Fig 1). No prior treatments had been attempted. The patient denied a history of oral herpes simplex and was determined to have Fitzpatrick skin type II. Before each procedure, local anesthetic with lidocaine, epinephrine, and sodium bicarbonate was infiltrated into the upper and lower lip margins. Prophylactic antibiotic (dicloxacillin) and antiviral medications (acyclovir) were given orally 1 day before each procedure and continued for 1 week postoperatively. The pulsed carbon dioxide laser, with a computer pattern generator (Coherent Laser, Santa Clara, Calif) was used at 10,600 nm, 300 mJ, 60 W. A linear scan pattern was used with a scan density of 6. The entire tattoo was resurfaced in 1 pass. The overlying vaporized tissue was wiped away with a moistened gauze leaving clinically apparent tattoo present. Bacitracin ointment was subsequently applied to the wound. Complete healing of the treated area took place after 4 days. The procedure was repeated at 1-month intervals. After 6 treatments, removal of the tattoo was essentially complete (Fig 2). No scarring or pigmentary change was evident. This report demonstrates safe and effective removal of a tattoo that likely contained iron oxide and that was at risk for paradoxical darkening from use of any of the Q-switched lasers. As with other tattoo laser procedures, complete response required multiple treatments with gradual clearing noted after each treatment. Q-switched lasers target the pigment located in tattoos through selective photothermolysis.4 The target of the pulsed carbon dioxide laser is water, leading to superficial tissue vaporization. Repetitive, conservative treatment sessions were performed by design to minimize the chance of hyperFrom the Laser & Skin Surgery Center of New York. Reprint requests: Roy G. Geronemus, MD, Laser & Skin Surgery Center of New York, 317 E 34th St, Suite 11 North, New York, NY 10016. E-mail: rgeroneumus@hotmail.com. J Am Acad Dermatol 2003;48:271-2. Copyright © 2003 by the American Academy of Dermatology, Inc. 0190-9622/2003/$30.00 0 doi:10.1067/mjd.2003.29 . Fig 1. Red lip-liner tattoo present at the vermillon border before treatment with the pulsed carbon dioxide laser.

Transurethral vaporization of the prostate

There are numerous abbreviations used to signify transurethral vaporization of the prostate: TVP, TUVP, TUEVP, and TUVRP. Regardless of which acronym is used, transurethral vaporization of the prostate entails the simultaneous vaporization, desiccation, and coagulation of prostatic tissue, using a rollerball or thick loop. TUVRP, which stands for transurethral vapor resection of the prostate specifically refers to the use of the thick-loop electrode and adds resection to the vaporization, desiccation, and coagulation accomplished with other electrodes. Otherwise the equipment is identical to that used for transurethral resection of the prostate (TURP). The generator must be capable of producing 25–45% higher wattage (2,4). The indications for TUVP are the same as those for TURP. This chapter will demonstrate that this modality is a modification of TURP.

Clinical evaluation of a newly developed endoscopicresection device (Rotoresect)

Endoscopic resection techniques on benign prostatic tissue aim at a high ablation rate and a minimal bleeding rate. Although commercial resection electrodes are effective, they either cause high blood loss (loop electrode) or reduce the bleeding rate with a compromised ablation rate (electrovaporization electrode). To resolve these problems, a new electrosurgical resection device, The Rotoresect, has been developed. The Rotoresect incorporates a specially designed working element. The resection electrode is driven by a micromotor with a high-frequency current that enables simultaneous coagulation and vaporization during rotoresection. To date, 40 patients with benign prostatic hyperplasia have undergone transurethral rotoresection of the prostate with this new device. The actively rotating resection electrode enables tissue coagulation and vaporization as well as mechanical tissue ablation. Only slight bleeding was observed during the entire resection procedure. Postoperatively, no significant changes in hemoglobin and sodium concentration were detected. The deobstructive effect of the Rotoresect was comparable to that of the standard loop. The simultaneous tissue vaporization, coagulation, and mechanical removal by the Rotoresect enables a high ablation rate combined with minimal blood loss. Initial clinical results gained in the transurethral resection of benign prostatic tissue are promising.

Gas and Air Embolization during Hysteroscopic Electrosurgical Vaporization: Comparison of Gas Generation Using Bipolar and Monopolar Electrodes in an Experimental Model

Study ObjectiveTo compare the composition of gases generated by bipolar hysteroscopic vaporizing electrodes using electrolyte-rich medium (normal saline) with those of monopolar vaporizing electrodes using nonelectrolytic medium (1.5% glycine). DesignIn vitro study (Canadian Task Force classification II-1). SettingLaboratory. InterventionFresh morbid bovine cardiac muscle was fully immersed in normal saline for the bipolar vaporizing electrode and 1.5% glycine for the monopolar vaporizing electrode. Standard hysteroscopic electrodes were activated at usual and maximum power outputs from radiofrequency electrosurgical generators appropriate for each system. The gases generated were captured and analyzed by gas chromatography and fast Fourier transform. Measurements and Main ResultsGaseous by-products of electrosurgical vaporization of test tissues largely consisted of hydrogen, carbon monoxide, and carbon dioxide. The composition of gases generated by hysteroscopic monopolar and bipolar electrodes in this laboratory model appear to be similar. ConclusionThese gases are all highly soluble in serum. This observation suggests that emboli of gaseous by-products of electrosurgery are unlikely to have an adverse impact on patients. On the other hand, air emboli, largely composed of relatively insoluble nitrogen, are more likely to result in clinically significant cardiopulmonary events.

Extent of myocardial tissue damage during transmyocardial laser revascularization with the CO2 Heart Laser.

Transmyocardial laser revascularization (TMR) is the only surgical treatment for patients with severe diffuse coronary artery disease, who are not candidates for bypass grafting or percutaneous angioplasty. However, vaporization of tissue during the creation of channels leads to a certain loss of viable myocardium during every TMR procedure. We analyzed serum levels of creatine kinase and creatine kinase MB subtype in 163 patients after sole TMR with a CO2 laser (wave length 10.6 microm, 800-watt power). The control group consisted of 35 consecutive CABG patients and 30 consecutive redo-CABG patients. Additionally, in the TMR group we measured echocardiographically the left ventricular ejection fraction before and after TMR. We recorded the total amount of laser energy applied, average and maximum energy per channel, and the number of created channels, in order to calculate the correlation between these parameters and postoperative enzyme levels or changes in the LVEF. After TMR, we measured higher creatine kinase levels compared to those in CABG patients (607.8+/-558.4 U/L vs. 285.0+/-292.3 U/L, p < 0.01). The relative proportion of CK-MB of total CK, however, was significantly lower after TMR, compared to that of the control group (4.5+/-3.0% vs. 10.1+/-6.4%, p < 0.01). Patients with a pronounced postoperative increase in CK-MB levels or a higher percentage of CK-MB of total CK also after TMR operations show a decline in left ventricular contractility. In the laser group, the maximum enzyme levels were detected significantly later than in the control group (25.0+/-19.4 h postoperatively vs. 8.7+/-9.1 h, p < 0.01). There was no significant correlation between the technical laser parameters or the number of created channels and the percentage of CK-MB of total CK or changes in left ventricular ejection fraction. CO2 laser TMR does not result in significant injury to the myocardium. Cardiac enzymes play an important role in the detection of perioperative myocardial infarction in TMR patients.

Ablation of Metastatic Ovarian Carcinoma with the Argon Beam Coagulator: Pathologic Analysis of Tumor Destruction

Objective. The aim of this study was to characterize the histopathologic effects of electrosurgical tumor destruction of metastatic ovarian carcinoma using the argon beam coagulator (ABC) and evaluate the depth of tissue damage produced by a range of power settings and tissue interaction times.Methods. Epithelial ovarian carcinoma tumor specimens (1 cm3) were harvested intraoperatively. Following surgical excision, electrosurgical destruction of tumor was effected using the ABC at three power settings (60, 80, and 100 W) and three tissue interaction time intervals (1, 3, and 5 s), yielding nine experimental groups of 16 samples each (n = 144). Samples were formalin-fixed, cross-sectioned, stained with hematoxylin and eosin, and examined microscopically for histologic characteristics and depth of tissue destruction.Results. Microscopic evaluation revealed that the total depth of destruction (TDD) produced by the ABC was composed of three distinct zones of tissue injury: vaporization, carbonized eschar (ESC), and coagulative necrosis (NEC). For each power setting, the mean TDD increased in a linear fashion as the interaction time interval increased from 1 to 5 s (60 W, 1.71 to 2.43 mm; 80 W, 2.24 to 3.69 mm; 100 W, 3.21 to 5.58 mm). By regression analysis, both power setting and tissue interaction time were independently associated with increasing TDD, with power having the strongest effect. At all power settings and interaction time intervals, the incremental change in TDD was primarily a function of the degree of tissue vaporization, which increased from 0.59 mm at 60 W (1 s) to 3.22 mm at 100 W (5 s). For all experimental groups, the ratio of NEC/ESC was highly consistent, ranging from 1.03 to 1.33 (P > 0.05, Bonferroni multiple comparisons procedure), and demonstrated that for each resulting ESC, an equivalent or greater degree of underlying NEC was also present.Conclusions. The destruction of ovarian carcinoma tumor tissue produced by the ABC is dependent upon both power setting and tissue interaction time. Increasing depth of destruction is due predominantly to a deeper level of tissue vaporization. The NEC/ESC ratio provides a reliable means of estimating the true depth of tumor destruction produced by the ABC and may contribute to increased safety and efficacy of electrosurgical cytoreduction of using this technique.

Transurethral vaporization of the prostate: Current techniques

Electrovaporization has quickly become a popular procedure for treating benign prostatic hyperplasia. By using standard transurethral electrosurgical technology, electrovaporization offers standard transurethral loop-like resection and transurethral prostatectomy (TURP)-like efficacy with less morbidity than that associated with TURP. Through a combination of two electrosurgical effects (vaporization and desiccation), electrovaporization ablates significant volumes of prostatic tissue with each passage of the electrode. Newly designed thicker loop electrodes have led to a modification of the original electrovaporization technique. "Vaporizing-resection" adds the advantages of transurethral resection to those of electrovaporization with the use of one electrode. Very large glands can be treated efficiently, and prostatic tissue specimens are produced. Moreover, additional vaporization of tissue occurs with minimized bleeding. This report reviews basic electrosurgical principles, electrode design, and factors that affect vaporizing efficiency. Current long-term data on electrovaporization compared with TURP are summarized, and pilot studies evaluating vaporizing- resection have shown promising results. A new technology that has entered the market--bipolar electrovaporization--is also discussed. Finally, combination therapy and Columbia's 4-year experience with vaporization techniques are discussed.

7179 Use of argon plasma coagulation (apc) in gastrointestinal angiectasia in an infant.

Background:APC is an alternative to conventional diathermy and ND:YAG laser for hemostasis of large surface bleeding. Features of benefit for small children include limitation of maximum penetration to a tissue depth of 3mm and no tissue vaporization, reducing the risk of perforation, and ease of application through small flexible endoscopes (2.2 mm channel). Case report: A nine month old male infant presented with melena, anemia and thrombocytopenia. Melena was not decreased by platelet infusions. Upper endoscopy revealed diffuse angioma in the stomach with bleeding but none in the duodenum or esophagus. Scattered bleeding lesions were seen in the colon. Epinephrine (1:1000) injections in the stomach, controlled bleeding briefly (24hrs) on 4 occasions.The 5th injection was complicated by tachyarrhythmia, hypertension and increased bleeding.e-aminocaproic acid, steroids and somatostatin were ineffective. Bleeding worsened over 2 months up to an RBC requirement of 30 cc/kg/day.The number of gastric lesions increased, especially in the fundus.APC was performed under general anesthesia with a Pentax EG2901 endoscope. A flexible APC probe was passed through the instrument channel to within 3-5 mm from the lesion. Argon flow at 0.7-0.9 l/min and coagulation current adjusted between 40-50 watts power with small bursts was sufficient for hemostasis and ablation of nonbleeding angiectasias. Melena stopped for 10-12 days following the procedure which was repeated on 5 occasions at 14 day intervals. New lesions were noted at successive endoscopies until treatment with interferona-2b reduced the appearance of new lesions.Complications included passage of a mild electric current once while the baby was being touched during the procedure and scar formation at the site of a fundic ulcer resulting from repeated ablation.Conclusion:Argon plasma coagulation is safe and effective in the management of multiple mucosal bleeding lesions in the GI tract in infants.

Sonographisch gesteuerte perkutane Hochfrequenzthermotherapie von Lebertumoren mit perfundierten Nadelelektroden

Percutaneous radiofrequency ablation (HFTT) is a new therapeutic technique for the treatment of inoperable primary and secondary liver tumors. We report our initial experience using a newly developed perfusion electrode. Twelve liver tumors (11 metastases of colorectal tumors, 1 hepatocellular carcinoma) were treated in 5 inoperable patients. The patients had 1 to 3 liver tumors. All lesions were cytologically confirmed and measured 12-47 mm. The technique was approved by the institutional review board and informed consent was obtained from all patients. A 12-mm-needle electrode with a 15-mm-active tip was introduced into the liver tumors under ultrasound guidance and tumors were coagulated with radiofrequency energy of 350 kHz. The needle electrodes were perfused with 0.9% saline during coagulation to increase the volume of coagulation necrosis without tissue vaporization. The serial changes in tumor size after therapy were evaluated with spiral CT imaging. Dynamic CT showed that unenhanced areas indicative of coagulation necrosis developed in all tumors. In 8 of 12 tumors no signs of recurrence appeared during the observation period of 7 (5-12) months. No major complications were observed. Our preliminary experience suggests that percutaneous radiofrequency coagulation can be a simple, safe and potentially effective treatment for selected patients with inoperable liver tumors. The results justify further studies to investigate the possible role in clinical practice.

Treatment of Upper Lip Wrinkles: A Comparison of the Sharplan SilkTouch Carbon Dioxide Laser with Ellman Radiosurgery

Introduction: High energy pulsed, or computer-scanned, continuous-wave carbon dioxide (CO2) laser has become a popular tool for wrinkle treatment because it causes minimal thermal injury and the tissue vaporization depth can be precisely controlled. Radiosurgery for this purpose has been used to a lesser extent, but is also beneficial for the treatment of facial wrinkles. The objective of this study was to compare the effectiveness and side effect profile of the Sharplan SilkTouch CO2 laser with those of the Ellman Surgitron FFPF radiosurgery unit in the treatment of upper lip wrinkles and is, to our knowledge, the first study to compare a CO2 laser with high-frequency radiosurgery for this purpose. Methods: Twenty female subjects with moderate to severe upper lip wrinkles were randomly treated with the SilkTouch CO2 laser on one side of the upper lip and radiosurgery on the other side. Results: The average laser-treated wrinkle score (0 = none to 5 = severe) decreased from 4.05 ± 0.2 before treatment to 1.6 ± 0.23 after treatment. The average radiosurgery-treated wrinkle score decreased from 4.2 ± 0.18 to 2.6 ±0.2 after treatment. The degree to which wrinkle score improved after laser treatment compared with radiosurgery treatment was statistically significant (P &lt; .0051). Conclusion: Treatment with CO2 laser resulted in greater improvement of upper lip wrinkles than did treatment with radiosurgery.

Cutaneous laser resurfacing

Cutaneous resurfacing with the new generation of carbon dioxide and erbium lasers has recently come into favor for the treatment of facial rhytides, photodamage, and scarring. The precise control of these resurfacing lasers over the extent of tissue vaporization minimizes thermal damage to the skin while maximizing therapeutic efficacy. Proper use of resurfacing lasers is contingent upon a complete understanding of their clinical, histologic, and ultrastructural effects, as well as an appreciation of the principles of laser safety. An organized approach to the preoperative, intraoperative, and postoperative management of the patient undergoing laser resurfacing will be provided, including a discussion of prevention and treatment of postoperative side effects and complications. (J Am Acad Dermatol 1999;41:365-89.) Learning Objective: At the conclusion of this learning activity, participants should be familiar with the clinical, histologic, and ultrastructural effects of resurfacing lasers and be able to discuss the preoperative, intraoperative, and postoperative management of patients undergoing laser resurfacing.

Laser pyrolysis products—genotoxic, clastogenic and mutagenic effects of the particulate aerosol fractions

Laser therapy has gained wide acceptance and application in many medical disciplines. Nevertheless, during surgical procedures, the thermal destruction of tissue creates a smoke plume. Recent research data indicate that pyrolysates liberated during vaporisation of tissue induce DNA damage. However, assessing potential health hazards during medical laser treatment requires comprehensive insight into the cytotoxic, genotoxic, clastogenic and mutagenic capacity of laser pyrolysis products (LPP). Therefore, the aim of this study was to evaluate the cytotoxic, genotoxic, clastogenic and mutagenic potential of substances resulting from laser irradiation. Four different types of porcine tissues were irradiated with a surgical CO 2 laser, the aerosols were sampled under defined conditions and subjected to the SCE test, micronucleus test and the HPRT test. The results showed that the pyrolysis products are strong inducers of cytotoxic effects. The pyrolysis products induced positive effects in the SCE test, micronucleus test and the HPRT test. The ability and extent to induce genotoxic and mutagenic effects turned out to be dependent on the type of tissue that had been irradiated. In general, the effects were most pronounced with liver pyrolysate. In all test systems, a clear dose relationship could be established. In conclusion, we were able to prove that the particulate fraction of laser pyrolysis aerosols originating from biological tissues undoubtedly have to be classified as cytotoxic, genotoxic, clastogenic and mutagenic. Therefore, they could be potential health hazards for humans.