Skin resurfacing of facial rhytides and scars with the 90-microsecond short pulse CO2 laser. Comparison to the 900-microsecond dwell time CO2 lasers and clinical experience

BACKGROUND

Carbon dioxide lasers that produce either short pulses or scanned continuous beams have been used for skin resurfacing to improve wrinkles or scars. Using a high peak power, short pulse CO2 laser can produce clinically effective results with minimal thermal damage.

OBJECTIVE

To evaluate the effectiveness of skin resurfacing using the 90-microsecond pulse duration CO2 laser compared to other laser systems. Erythema, healing time, complications, and histological measurement of the depth of ablation and thermal damage per pass with this system were also assessed.

METHODS

Forty-one patients with facial rhytides and scars underwent resurfacing with a 90 microseconds pulse duration CO2 laser. Using patient survey, patients were evaluated for effectiveness of therapy, healing time, and complication rates. Comparisons of histologic and clinical findings were made with different short pulse CO2 lasers.

RESULTS

Healing time, duration of erythema, and post-operative pain were less with the 90 microseconds pulse CO2 laser than with the 900-microsecond dwell time and 950-microsecond pulse duration lasers, while effectiveness was comparable. Complications were few with the 90-microsecond pulse laser, including three patients (9.1%) developing hyperpigmentation. One pass with the 90-microsecond pulse duration CO2 laser produced 100 microns of ablation with 17 microns of thermal damage. Ablation and damage were additive so that, by six passes, ablation depth was 350 microns and depth of thermal damage was 63 microns. This thermal damage is less than that reported with lasers having a longer pulse duration or dwell time with comparable depths of vaporization.

CONCLUSION

Treatment with the 90-microsecond pulse duration laser results in a more rapid healing time and shorter duration erythema. The clinical improvements in wrinkles and sun damage were comparable. The 90-microsecond pulse duration laser provides an effective, predictable, and safe means of improving facial rhytides and scars.

Grafting following short-pulse carbon dioxide laser de-epithelialization

BACKGROUND

Dermabrasion followed by skin grafting has been used for treatment of depigmentation. The short pulsed carbon dioxide (CO2) laser allows removal of the epidermis but leaves necrosis on the surface of the dermis.

OBJECTIVES

The purpose of this study was to determine if the thermal necrosis would interfere with the take of skin grafts.

METHODS

Two vitiliginous areas of skin were de-epithelialized, one by conventional dermabrasion and the other with a pulsed CO2 laser. Each area was biopsied for histologic study and grafted with a split-thickness skin graft.

RESULTS

Histologic studies of the wounds were compared. The residual tissue destruction on the dermis of each area was quite similar. The skin graft take was excellent in both areas.

CONCLUSIONS

The short pulsed CO2 laser does not cause sufficient thermal necrosis on the surface of the papillary dermis to interfere with a satisfactory skin graft take.

Tumescent anesthesia with a lidocaine dose of 55 mg/kg is safe for liposuction

BACKGROUND

The safe upper limit of lidocaine dosage in tumescent anesthesia for liposuction has been reported to be 35 mg/kg.

OBJECTIVE

This study was undertaken to: 1) evaluate the safety of tumescent anesthesia in liposuction when lidocaine doses greater than 35 mg/kg are required, 2) determine the time interval when the peak plasma lidocaine level occurs following administration of tumescent anesthesia, and 3) assess if the safety of large volume tumescent anesthesia is due to significant lidocaine removed by liposuction.

METHODS

Sixty patients who underwent liposuction with a mean lidocaine dose of 57 mg/kg were prospectively evaluated for development of any signs or symptoms of lidocaine toxicity by multiple interviews over a 24-hour period. In addition, another 10 patients who received a mean lidocaine dose of 55 mg/kg had serial plasma lidocaine level measurements over a 24-hour period following liposuction. The lidocaine level of the aspirate was also measured to assess any significant lidocaine removed by liposuction.

RESULTS

No evidence of lidocaine toxicity was found based on subjective evaluation of 60 patients as well as determined by plasma sampling of 10 patients. The peak plasma lidocaine concentration occurred at approximately 4 or 8 hours after infusion of tumescent anesthesia. The 24-hour plasma lidocaine level suggests that residual lidocaine is present in the subcutaneous tissue allowing for postoperative analgesia beyond this time. A negligible amount of lidocaine was removed by liposuction as determined by the lidocaine level of the aspirate.

CONCLUSION

This study suggests that tumescent anesthesia with a total lidocaine dose of up to 55 mg/kg is safe for use in liposuction.

A clinical and histologic evaluation of two medium-depth peels. Glycolic acid versus Jessner's trichloroacetic acid

BACKGROUND

Chemical peels using alpha hydroxy acids have become one of the most frequently requested dermatologic procedures. The use of glycolic acid in superficial chemical peels is now well established. However, the role of glycolic acid in medium-depth chemical peels has yet to be elucidated.

OBJECTIVE

We performed a clinical and histologic comparison of 70% glycolic acid versus Jessner's solution as part of a medium-depth chemical peel using 35% trichloroacetic acid (TCA).

METHODS

Thirteen patients with actinic keratoses, solar lentigines and fine wrinkling were evaluated prospectively. Each patient was treated with 70% glycolic acid plus 35% TCA (GA-TCA) to the right face and Jessner's solution plus 35% TCA (JS-TCA) to the left face. Clinical and histologic changes were evaluated at 7, 30, and 60 days postoperatively.

RESULTS

Clinically, the GA-TCA peel was effective in treating photodamaged skin. The GA-TCA peel was slightly more efficacious in removing actinic keratoses (clinical response score = 1.5) than the JS-TCA peel (clinical response score = 1.0). Histologically, the GA-TCA peel caused the formation of a slightly thicker Grenz zone (mean = 0.053 mm) 60 days postpeel than the JS-TCA peel (mean = 0.048 mm) (not statistically significant). The GA-TCA peel caused more neoelastogenesis than the JS-TCA peel, while the JS-TCA peel resulted in more papillary dermal fibrosis and neovascularization than the GA-TCA peel.

CONCLUSION

The GA-TCA peel is a new medium-depth chemical peel that is effective in treating photodamaged skin.