Laser-Assisted Hair Transplantation: Histologic Comparison Between CO2 and Ho:YAG Lasers

BACKGROUND: Various laser wavelengths and devices have been advocated for use in the creation of recipient channels during hair transplant surgery, including flash-scanned CO2, Ho:YAG (lambda = 2.12 microm), and Er:YAG (lambda = 2.94 microm). OBJECTIVE: To determine the tissue injury caused by flash-scanned CO2 and pulsed Ho:YAG lasers during the creation of hair transplant recipient channels and to assess the efficacy of the Ho:YAG laser. METHODS: Recipient channels were created in vivo in human scalp tissue using both lasers, and were excised and prepared for histologic examination. Optical micrometry of tissue sections was used to assess thermal injury. RESULTS: The Ho:YAG laser created jagged, irregular-shaped channels with larger zones of thermal injury (superficial deepithelialization, thermal necrosis, and thermal damage). In contrast, the CO2 laser produced well-defined cylindrically shaped channels free of cellular debris with minimal epithelial disruption and significantly less lateral thermal injury. CONCLUSION: Given that the Ho:YAG produced larger regions of thermal injury and recipient channels that were unacceptable for graft, the CO2 laser remains the better choice for the creation of recipient channels during hair transplant surgery. However, ongoing research will be necessary to determine the optimal laser wavelength and/or devices for this procedure.     

One-Pass CO2 Versus Multiple-Pass Er:YAG Laser Resurfacing in the Treatment of Rhytides: A Comparison Side-by-Side Study of Pulsed CO2 and Er:YAG Lasers

BACKGROUND: The CO2 laser is normally described as an aggressive resurfacing tool, whereas the erbium:YAG laser has enjoyed a reputation as the ideal tool for superficial resurfacing. The implication from many studies is that the CO2 laser is incapable of "minimally invasive" resurfacing. OBJECTIVE: To compare a short-pulsed CO2 laser with an Er:YAG laser over a range of parameters intended to produce equivalent microscopic and clinical injuries. METHODS: A prospective, randomized, comparative interventional trial was conducted in a tertiary care teaching hospital. Thirteen patients with facial wrinkles were enrolled in the study. A side-by-side comparison was performed using periorbital and perioral regions as treatment sites. One side was treated with a pulsed CO2 laser and the other with an Er:YAG laser. Postauricular skin was treated in an identical fashion to the study sites and biopsied for microscopic analysis. The biopsies were obtained before treatment, immediately after treatment, and either 3 or 6 months after treatment to evaluate the acute level of injury and subsequent degree of fibroplasia. Photographs were taken at baseline, immediately after treatment, 1, 2, and 6 weeks, and 3 and 6 months after treatment. Nine physicians evaluated the photographs for erythema, pigmentation, and wrinkle improvement. RESULTS: Investigator assessment showed no statistically significant differences between the lasers with respect to hyperpigmentation and wrinkle reduction. There was less erythema at the CO2 laser-treated sites 2 weeks after treatment; the differences had resolved by 6 weeks after treatment. Histologic examination demonstrated equivalent dermal thermal injury on immediate postoperative biopsies and equivalent fibroplasia on subsequent biopsies. Both CO2 and Er:YAG laser-treated sites showed overall modest wrinkle improvement compared to the pretreatment photographs. CONCLUSION: When CO2 and Er:YAG lasers are used in a manner such that there are equivalent immediate postoperative histologic results, equivalent healing and cosmetic improvement occurs. One can use CO2 laser with one pass to mimic a moderately aggressive Er:YAG laser treatment.     

Laser Resurfacing of the Neck with the Combined CO2/Er:YAG Laser

BACKGROUND: Several clinical studies on laser resurfacing on the neck have yielded variable results with adverse sequelae of hypopigmentation and scarring using the CO2 laser. The Er:YAG laser on the neck resulted in an improved appearance with no adverse sequelae. The combined CO2/Er:YAG laser is a laser that combines a low fluence CO2 laser with the Er:YAG laser in a near simultaneous beam. OBJECTIVE: To study the effects of the CO2/Er:YAG laser on the neck. The decreased nonspecific thermal damage of the CO2/Er:YAG laser should result in decreased postoperative erythema and improved wound healing. METHODS: Eleven patients were treated with the CO2/Er:YAG laser on the neck as well as the face at identical settings. The face was treated with four passes while the neck was treated with two passes. The patients were evaluated for the first 2 weeks then 3-6 months postoperatively. Patients were asked about treatment satisfaction and improvement in skin texture and color using a 25% scale. Skin texture and color, as well as improvement in wrinkling and adverse results were judged by a dermatologist using a 0-4 scale. RESULTS: Moderate improvement was seen in skin color while a higher degree of improvement was seen in skin texture and wrinkling in all 11 patients. No adverse sequelae, including hypopigmentation or scarring, were observed. The majority of patients had a 75-100% improvement in skin texture and color in addition to a 75-100% overall satisfaction rating. CONCLUSIONS: There is a higher degree of overall patient satisfaction, as well as improvement in skin texture and skin color, compared to patients treated with the Er:YAG laser alone. The CO2/Er:YAG laser is a highly effective laser for neck resurfacing with no adverse sequelae to date.     

Laser Skin Resurfacing of the Face with a Combined CO2/Er:YAG Laser

BACKGROUND: A combined, dual-wavelength CO2/Er:YAG laser system having the ability to deliver both clean ablation of skin with the erbium wavelength and a simultaneous deeper penetrating subablative thermal pulse of CO2 was developed for full-face resurfacing. The CO2 component can be pulsed from 1 to 100 msec at a power of 1-10 W with the Er:YAG component pulsed at 350 microsec at 1.7 J/cm2 through either a computer pattern generator with 3 mm diameter spot size or through a noncollimated spot ranging from 0.2 to 8 mm in diameter. Our previous study using this laser on the neck using a 4-8 mm diameter spot with Er:YAG fluence at 1.7 J and the CO2 at 5 W with a 50 msec pulse at a frequency of 10 Hz showed a higher degree of overall patient satisfaction, as well as improvement in skin texture and skin color, compared to patients treated with an Er:YAG laser alone. OBJECTIVE: This study evaluated the CO2/Er:YAG laser treatment modality in facial resurfacing. METHODS: Ten patients were treated with four passes at 1.7 J with a 4 mm diameter spot and the CO2 at 5 W with a 50-msec pulse at a frequency of 10 Hz. Photoaging scores as well as thermal damage and new collagen formation were compared immediately before and after treatment as well as at 2 weeks and 3 months postoperatively. RESULTS: The average pretreatment periorbital score was 6.2 The average posttreatment periorbital scores were 4.2 (P =.0239) at 2 weeks postoperatively (32% improvement) and 3.8 (P =.0028) at 3 months postoperatively (38% improvement). The average pretreatment perioral score was 5.9. The average posttreatment perioral scores were 3.0 (P =.0001) at 2 weeks postoperatively (49% improvement) and 3.3 (P =.0009) at 3 months postoperatively (44% improvement). The average pretreatment cheek score was 4.7. The average posttreatment cheek scores were 2.7 (P =.0066) at 2 weeks postoperatively (43% improvement) and 3.8 (P =. 0152) at 3 months postoperatively (36% improvement). The average pretreatment forehead score was 4.7. The average posttreatment forehead scores were 3.8 (P =.0340) at 2 weeks postoperatively (33% improvement) and 3.6 (P =.0147) at 3 months postoperatively (37% improvement). The average depth of collagen measured in the dermis pretreatment was 29 microm. The average depth of collagen 3 months posttreatment was 54 microm. This is an average increase of 25 microm or an 86% increase in collagen (P =.006). The average thermal damage immediately after treatment was 20 microm. CONCLUSION: The CO2/Er:YAG laser utilized with four passes at the above-mentioned parameters results in a similar degree of improvement as other forms of laser resurfacing with high-energy, short-pulsed CO2 lasers.     

Dermabrasion Using CO2 Dry Ice

BACKGROUND: The cosmetic dermatologic surgeon can improve facial scars by using a variety of techniques. Chemical peels, lasers, and dermabrasion are among the most common modalities used. In recent years, laser resurfacing has enjoyed great popularity; however, there is still a role for the time-honored and effective technique of dermabrasion. The recent withdrawal of Freon from the market has made dermabrasion more difficult. OBJECTIVE: To introduce a novel technique of using solid carbon dioxide (CO2) to freeze the skin before dermabrasion. METHOD: Twenty-five consecutive patients with facial acne scars underwent a combination of procedures including chemical peeling and CO2 laser resurfacing, followed by freeze-dermabrasion. Compressed CO2 was then used to make a solid ball of dry ice. The ice was used to freeze the skin prior to dermabrasion. After the application of the dry ice ball to the skin for about 4 seconds, the scares were dermabraded with the large mushroom wheel. As the tissue defrosted, the operator started at the outer edge of the freeze and planed into the center. This procedure was repeated until the desired improvement was achieved. RESULTS: With dry ice, a good skin turgor was achieved. This provided a good foundation for the sanding of the acne scars. The patients were pleased with the results and complications were minimal. CONCLUSION: "Home-made" dry ice works as well as Freon in providing skin turgor for dermabrasion. CO2 dry ice has the added benefits of being inexpensive and environmentally friendly.     

Treatment of Atrophic Facial Scars with Combined Use of High-Energy Pulsed CO2 Laser and Er:YAG Laser: A Practical Guide of the Laser Techniques for the Er:YAG Laser

BACKGROUND: Although CO2 laser resurfacing provides substantial clinical improvement for atrophic facial scars, the CO2 laser often results in excessive thermal damage to the skin. It increases complications postoperatively. The Er:YAG laser ablates thinner layers of tissue than the CO2 laser with minimal thermal damage to the surrounding skin. OBJECTIVE: To determine the efficacy of combined treatment of atrophic facial scars with high-energy pulsed CO2 laser and Er:YAG laser. METHODS: One hundred fifty-eight patients were treated with a combination of high-energy pulsed CO2 laser and Er:YAG laser for atrophic facial scars. All patients were evaluated after 3 months of treatment. RESULTS: The scars improved 80-89% in 65 patients, 70-79% in 56 patients, more than 90% in 32 patients, 60-69% in 2 patients, and less than 60% in 3 patients after laser treatment. CONCLUSION: Treatment of atrophic facial scars with combined use of high-energy pulsed CO2 laser and Er:YAG laser is a very effective and useful method.     

Prolonged Clinical and Histologic Effects from CO2 Laser Resurfacing of Atrophic Acne Scars

BACKGROUND: The recent development of high-energy pulsed CO2 lasers that minimize thermal injury to uninvolved adjacent structures has revolutionized the manner in which atrophic facial scars are recontoured. Significant improvement of atrophic scars with laser resurfacing has clearly been demonstrated; however, the exact timing for assessment of skin for further treatment has varied due to the unknown amount of time needed after laser scar resurfacing to effect maximal collagen formation and remodeling. OBJECTIVE: The aim of this study was to determine the immediate and long-term (12-18 months) histologic and clinical effects of atrophic acne scars after CO2 laser resurfacing in order to provide physician guidelines for postoperative clinical assessment for retreatment. METHODS: Sixty patients (50 women, 10 men, mean age 38 years, skin types I-V) with moderate to severe atrophic facial scars were evaluated. Nineteen patients received regional cheek treatment and 41 patients received full-face resurfacing with a high-energy pulsed CO2 laser. Independent clinical assessments of treated scars were performed at 1, 6, 12, and 18 months and blinded histologic analyses were made of skin biopsies immediately prior to and after laser resurfacing, and at 1, 6, 12, and 18 months postoperatively in six patients. RESULTS: Significant immediate and prolonged clinical improvement in skin tone, texture, and appearance of CO2 laser-irradiated scars was seen in all patients. Average clinical improvement scores were 2.22 (69%) at 1 month, 2.1 (67%) at 6 months, 2.37 (73%) at 12 months, and 2.5 (75%) at 18 months. Continued collagenesis and subsequent dermal remodeling were observed on histologic examination of biopsied tissue up to 18 months after surgery. CONCLUSION: Continued clinical improvement was observed as long as 18 months after CO2 laser resurfacing of atrophic scars, with an 11% increase in improvement observed between 6 and 18 months postoperatively. We propose that a longer postoperative interval (12-18 months) prior to assessment for re-treatment be advocated in order to permit optimal tissue recovery and an opportunity for collagen remodeling.     

Combined Laser Resurfacing with the 950-μsec Pulsed CO2+ Er:YAG Lasers

INTRODUCTION: Laser resurfacing with the 950 microsec pulsed CO2 laser has been proven to be efficacious in improving photodamaged skin and acne scarring. Unfortunately, prolonged erythema and delayed wound healing are common adverse sequelae, which require intensive patient education and intervention. These adverse effects may be due to the degree of nonspecific thermal damage present after resurfacing with the CO2 laser. Since erbium: YAG (Er:YAG) laser vaporization leaves far less thermal damage, it is hypothesized that its use after CO2 laser resurfacing will decrease the extent of nonspecific damage and result in improved wound healing. METHODS: Ten patients were randomized to receive laser resurfacing of one-half of the face with the 950 Msec pulsed CO2 laser with 3 passes at 300 mJ, utilizing the computer pattern generator (CPG) at settings of 596, 595, 584, and the other half of the face (randomly chosen) resurfaced with the 950 Msec pulsed CO2 laser 2 passes with the CPG at 300 mJ at settings of 596 and 595, followed by 2 passes with the Er:YAG laser (Derma-20 or Derma-K, ESC Medical Systems, Inc., Needham, MA) with a 4 mm diameter spot size at 1.7 J (approximately 14 J/cm2). Patients were evaluated in a "blinded" manner clinically and histologically before resurfacing, immediately after resurfacing, 2 to 3 days postoperatively, 1 week postoperatively, and, 4 to 8 weeks postoperatively. RESULTS: There was slightly less inflammation with the CO2/Er:YAG-treated patients. The epidermis re-formed 1 to 2 days faster with combination (UPCO2)/Er:YAG treatment than with UPCO2 laser treatment alone. In 7 of 10 patients, Er:YAG erythema resolved within 2-3 weeks with CO2 x 3 erythema persisting at the 8-week follow-up period in all patients. Three of 10 patients had no difference in the degree of erythema between the 2 treatment areas. Clinical findings correlated with histologic findings of vascularity. There was no difference in the extent or time of edema between techniques. The usual demarcation line between cheek and neck at the mandibular angle was less apparent when the UPCO2/Er:YAG combination was used. Two of 10 patients noted quicker healing with the combination laser technique. CONCLUSION: Treating a patient with the Er:YAG laser after treatment with the UPCO2 laser results in a decreased incidence of adverse sequelae without a noticeable difference in the degree of wrinkle improvement.     

Treatment of Facial Skin Using Combinations of CO2, Q-Switched Alexandrite, Flashlamp-Pumped Pulsed Dye, and Er:YAG Lasers in the Same Treatment Session

BACKGROUND: Many patients who seek facial CO2 laser resurfacing for improvement of photodamage are also concerned with "dark circles" under their eyes (periorbital hyperpigmentation) and/or telangiectasia as well as various types of deep scars on their faces. CO2 laser resurfacing alone provides limited improvement for these problems. OBJECTIVE: The purpose of this study was to demonstrate the conjunctive therapeutic effects of the CO2, Q-switched alexandrite, Er:YAG, and/or flashlamp-pumped pulsed dye lasers on facial skin treatments. METHOD: Thirty patients who underwent CO2 laser resurfacing were treated with additional lasers specific for their cosmetic concerns. Twenty patients with facial telangiectasias were treated with the pulsed dye laser immediately prior to CO2 laser resurfacing. Eleven patients with periorbital hyperpigmentation were treated with the Q-switched alexandrite laser immediately following use of the pulsed CO2 laser. Eight patients having sharply defined acne scars were treated with the Er:YAG laser following use of the CO2 laser. All patients had peripheral feathering performed with the Er:YAG laser. Nine patients were treated with all four lasers. RESULTS: In addition to significant improvement of the wrinkle scores from the CO2 laser resurfacing, patients had 75-100% clearing of the periorbital hyperpigmentation. All patients with facial telangiectasia showed virtually 100% improvement. All deep wrinkles and sharply defined scars responded with combined CO2/Er:YAG laser better than with CO2 laser resurfacing alone. All feathering was more uniform, with a more subtle transition to nontreated skin. There were no complications that could be attributed to the simultaneous use of multiple lasers. CONCLUSIONS: For patients who present with multiple cosmetic complaints, combined treatment using appropriate lasers offers excellent therapeutic outcome.     

End-tidal CO2 monitoring

Two cases of malignant hyperthermia are described where the earliest sign was a rise in the end-tidal CO2 concentration. This led to nearly immediate detection and adequate treatment with sodium dantrolene. These cases demonstrate the efficacy of monitoring end-expired CO2 concentrations in patients at risk from malignant hyperthermia, as well as a means for following the adequacy of treatment.     

A Surgical Approach to Ingrown Nail: Partial Matricectomy Using CO2 Laser

BACKGROUND: Ingrown nail is a deformity characterized by a transverse overcurvature of the lateral nail plate that causes nail fold inflammation. Currently recommended surgical procedures vary considerably. OBJECTIVE: We report our experience with a modified partial matricectomy and nail edge excision with CO2 laser. METHODS: A total of 116 ingrown nail edges in 77 patients were treated with the procedure. RESULTS: The incidence of recurrence was 2 of 76 cases (2.6%). CONCLUSION: This new surgical approach was found to be effective and is presented as an alternative treatment technique.     

Airway Deadspace, End-Tidal CO2, and Christian Bohr

In order to calculate alveolar deadspace, an important measure of ventilation/perfusion mismatching, it is necessary to measure airway or anatomical deadspace (VDaw) and physiological deadspace. VDaw is usually measured graphically or by similar means, but sometimes it is estimated from a formula, based on Christian Bohr's work, in which end-tidal PCO2 is used as a measure of alveolar PCO2. In 58 patients undergoing anaesthesia and positive pressure ventilation, there were large errors in this estimate of VDaw compared to a graphical method. At tidal volumes of 400-500 ml, the median error was 34 ml; at larger tidal volumes, the median error increased to 74 ml (P less than 0.001). The size of the error was correlated to the slope of phase III, the part of the CO2 tracing representing alveolar CO2, at both ventilator settings (P less than 0.01). It is concluded that estimates of VDaw based on end-tidal PCO2 are unreliable, and their use will lead to a large part of the alveolar deadspace being wrongly accredited to VDaw.     

CO2 production after suxamethonium and diazepam

The CO2-production and degree of relaxation after increasing doses of suxamethonium were measured in seven patients undergoing alloplastic surgery of the hip. The study indicates that the CO2-production rises following the injection of increasing doses of suxamethonium. Another group of patients received diazepam 0.1 mg kg-1 before the injection of suxamethonium 1 mg kg-1. CO2-production was significantly reduced compared to CO2 production when suxamethonium was not preceded by diazepam. It is suggested that diazepam in doses larger than 0.1 mg kg-1 might be effective in preventing fasciculations and postoperative muscle pains before the injection of suxamethonium in a dose of 0.5 mg kg-1.