Laser Flashcards
After laser removal of an elaborate multi-color tattoo, a patient has residual green ink remaining. Which of the following is the most appropriate treatment for this residual pigment?
A) Carbon dioxide laser B) Intense pulsed light C) Long pulse Nd:YAG (1064-nm) laser D) Q-switched alexandrite (755-nm) laser E) 70% Trichloroacetic acid peel
The correct response is Option D.
Green tattoo ink responds effectively to treatment with a 755-nm Q-switched alexandrite laser. As of 2013, a picosecond-domain alexandrite laser became commercially available, giving 75% clearance of green pigment in just one to two treatments in fair-skinned patients. Alternatively, ruby lasers, with a 694-nm wavelength, can be used.
The 1064-nm wavelength is very effective for black and other dark colors when a Q-switched or picosecond machine is used. Typically, this wavelength is less effective for green, with this color commonly being left behind after completion of a 1064-nm treatment series.
The long-pulse Nd:YAG is used for hair removal and varicose veins. It does not have the short pulse width required for effective tattoo removal. Similarly, intense pulsed light (IPL), even when filtered to the correct wavelength, doesn’t give the short pulse width required for tattoo removal. Long-pulse laser or IPL pulses in the millisecond domain usually result in incomplete tattoo clearance, thermal damage to surrounding tissues, and scarring.
Trichloroacetic acid (TCA) peels are not pigment-specific. They have become popular with the do-it-yourself patient population, with unregulated sales over the Internet, leading to reports of hypertrophic scarring and chemical burns requiring formal excision and skin grafting. A TCA peel is not recommended as a tattoo treatment, even in the more commonly used concentrations of 30 to 40%, which are used for facial resurfacing.
Carbon dioxide laser is not effective at targeting tattoo pigment.
2017
A 55-year-old woman with moderate sun damage to facial skin and facial wrinkles comes to the office for laser skin resurfacing. Which of the following is the most appropriate management regarding respiratory protection from the laser smoke plume?
A) High-efficiency smoke evacuator placed 20 to 25 cm away from the site of the laser plume
B) High-efficiency smoke evacuator placed within 1 to 2 cm of the smoke plume
C) Standard surgical mask alone
D) Standard wall suction
E) No specialized equipment or protection is necessary
The correct response is Option B.
Along with ocular hazards and fire hazards, laser smoke plume is a significant occupational hazard, which is often ignored when lasers are used. There are numerous substances, some carcinogenic and mutagenic, released during laser pyrolysis of tissue. Viable skin bacteria, including coagulase-negative Staphylococcus, Corynebacterium, and Neisseria, have been recovered from the laser plume following laser skin resurfacing. In addition, intact viral DNA, particularly of human papillomavirus, has been isolated from carbon dioxide laser plume. Most surgical masks only filter particles that are 5 microns in diameter or larger; however, 77% of particles in the laser plume are 1 micron or smaller. Therefore, well-fitted high-filtration or laser masks should be used instead of standard surgical masks. A high-efficiency smoke evacuator should also be used, but it needs to be within 1 to 2 cm of the laser smoke plume source. The effectiveness of the smoke evacuator is decreased from 99 to 50% as the distance from the laser-treated site is increased from 1 to 2 cm, so 20 to 25 cm away is ineffective.
2015
Which of the following is most effective in decreasing the risk of fire when using a carbon dioxide laser for facial resurfacing?
A) Clamp the laser cord to surgical drapes
B) Intubate laser patients to prevent oxygen accumulation on the field
C) Provide supplemental oxygen with a nasopharyngeal cannula
D) Use conscious sedation, nerve blocks, and no supplemental oxygen
E) Use foot pedals only for activating the laser
The correct response is Option D.
Carbon dioxide laser treatments can cause operating room fires. Several papers have shown that a nasopharyngeal oxygen delivery can decrease oxygen levels in the operative field when it is required, but the best way to decrease the level of oxygen on the field is not to use it. Foot pedals can be accidentally activated and should be avoided. Clamping the laser cord can damage the fibers and ignite the laser fiber sheath. Laser skin surfacing can be accomplished without intubation.
2015
A 24-year-old woman comes to the office because of a capillary malformation of the right cheek. Which of the following lasers is the most appropriate treatment in this patient?
A) Carbon dioxide laser (10,200 nm) B) Er:YAG (2940 nm) C) Nd:YAG (1064 nm) D) Pulsed-dye (585 nm) E) Q-switched ruby (694 nm)
The correct response is Option D.
The chromophore for the pulsed-dye laser at a wavelength of 585 nm is oxyhemoglobin. Thus, this laser is best suited to treat vascular lesions.
Rhytides, acne scars, and dyschromias can also be managed by ablative resurfacing techniques, such as a carbon dioxide laser, which is absorbed by water.
Er:YAG has a wavelength of 2940 nm and is absorbed by water. This laser causes less collateral thermal necrosis than a carbon dioxide laser.
Acne scarring is best managed with infrared lasers at wavelengths of 1064 to 1540 nm. These include the Nd:YAG, diode, and erbium lasers.
Tattoos are best managed with a Q-switched ruby laser at a wavelength of 694 nm, which is absorbed by melanin and carbon pigments.
2013
A 54-year-old woman comes to the office because of severe facial rhytides and photodamage. Examination shows Fitzpatrick skin type III. Ablative laser resurfacing is planned. Which of the following is the most likely complication of laser resurfacing in this patient?
A) Acneiform eruption B) Bacterial infection C) Erythema D) Hyperpigmentation E) Scarring
The correct response is Option D.
Hyperpigmentation is the most common adverse effect of laser resurfacing. It occurs in 36% of patients and is most common in people with Fitzpatrick skin Types III to VI. Treatment consists of hydroquinone and tretinoin. Sun exposure should be avoided. Rates of hyperpigmentation can be reduced in those pretreated with retinoic acid and bleaching agents. While hyperpigmentation can be permanent, with proper treatment it usually resolves within a few months.
Acne can occur post-laser treatment. It is especially common in patients with a prior history and should be treated with standard acne therapies. Infection risk from bacteria is minimized with prophylactic antibiotics and good topical care. Viral herpes simplex outbreaks can occur in those with and without a history. Antiviral prophylaxis is now used in all patients undergoing laser resurfacing. Yeast infections are also a possible infectious complication. These respond well to systemic antifungals. Scarring can occur with improper technique that causes excessive thermal damage (i.e., too many passes and excessive energy fluencies). Areas that develop scarring can be treated with topical and intralesional corticosteroids, silicone sheeting, and pulsed-dye laser. Erythema is not considered a complication and is a normal part of the healing process. It can last 1 to 4 months depending on the type of laser used.
2013
A 46-year-old woman comes to the office for evaluation of persistent erythema 2 weeks after she underwent full-face carbon dioxide laser resurfacing. Which of the following topical treatments is most appropriate to decrease this patient’s postoperative erythema?
A) Amoxicillin B) Ascorbic acid C) Hydroquinone D) Prednisone E) Valacyclovir
The correct response is Option B.
Erythema following laser resurfacing is an anticipated consequence of therapy. Posttreatment erythema is more severe and of longer duration with carbon dioxide laser resurfacing when compared to the fractionated carbon dioxide or Er:YAG laser. Postoperative topical application of ascorbic acid has been shown to decrease the duration as well as the severity of erythema. Topical therapy with ascorbic acid should be applied following reepithelialization. Antibiotics or antivirals have not been shown to decrease erythema. Hydroquinone is a skin bleaching agent that does not treat erythema. Topical corticosteroids postoperatively may delay reepithelialization and have not been associated with a decrease in erythema.
2013
A 38-year-old woman comes for consultation regarding facial laser resurfacing. Physical examination shows Fitzpatrick Type III skin with facial dyschromia. Which of the following is the most likely side effect of fractional carbon dioxide laser resurfacing in this patient?
A ) Contact dermatitis B ) Dermal scarring C ) Ectropion D ) Hyperpigmentation E ) Rosacea
The correct response is Option D.
Pigmented skin, Fitzpatrick Type III or IV, tends to absorb about 40% more laser energy than nonpigmented skin. Thermal damage can extend beyond the area of treatment. For these reasons, physicians should be aware of the side effects and complications of ablative laser treatment in pigmented skin.
The most common side effect is hyperpigmentation. Hyperpigmentation usually occurs within 6 weeks to 6 months following laser ablation and is present in 100% of darkly skinned patients. Hyperpigmentation is most often transient and can persist for 9 months to 1 year. Recommended treatment is hydroquinone.
Contact dermatitis can occur secondary to topical antibiotic therapy such as neomycin or bacitracin. Less common side effects include dermal scarring, herpetic infections, or ectropion.
2012
A 22-year-old man comes for consultation regarding laser removal of a tattoo located on the upper lateral arm. He said his friend tattooed him 6 years ago using a sewing needle and black pen ink. Physical examination shows Fitzpatrick Type IV skin. Which of the following laser treatments is most likely to decrease the risk of scarring in this patient?
A ) Argon-pumped tunable dye B ) Carbon dioxide C ) Er:YAG D ) Flash lamp-pumped pulsed-dye E ) Q-switched ruby
The correct response is Option E.
Most amateur tattoos are characterized by pigment deposited at variable, sometimes excessive depths compared with those produced by a professional apparatus. This may compromise the ability to erase the tattoo in a single session or at all without resorting to more traditional measures, such as direct excision. The chromophore of the carbon dioxide laser is water; therefore, it will indiscriminately destroy unaffected skin, as well as the skin containing tattoo pigment. Fitzpatrick Type IV skin is that which, while resistant to sunburn, is more likely to demonstrate a genetic predisposition to hypertrophic scarring. Ablative laser treatment has been shown to adversely affect the risk of hypertrophism. Current safety guidelines require that all individuals present during laser therapy don appropriate eyewear, selected according to the laser wavelength. Q-switched lasers, including ruby, Nd:YAG, and alexandrite types, are based on the principle of selective photothermolysis. They are suited for removal of black tattoo pigments as well as a variety of colors while minimizing the risk of scar.
2012
An 8-month-old boy is brought to the office for evaluation of a capillary malformation involving the right side of the chest and right cheek. Physical examination shows red cutaneous discolorations in a dermatomal distribution. Which of the following lasers is most appropriate to treat this condition?
A ) Carbon dioxide laser (10,200 nm) B ) Nd:YAG (1064 nm) C ) Pulsed-dye (585 nm) D ) Q-switched alexandrite (755 nm) E ) Q-switched ruby (694 nm)
The correct response is Option C.
Pulsed-dye laser with epidermal cooling remains the standard means of treating port-wine stains in the pediatric population. Intense pulsed-light devices have also been used with some effectiveness. The principles of selective thermolysis play a critical role in optimizing the treatment of port-wine stains. Oxyhemoglobin serves as the target chromophore, exhibiting three absorption peaks (418, 542, and 577 nm). Currently, the 585-nm and 595-nm pulsed-dye lasers appear to be the most popular choices and are most effective because of their proximity to an absorption peak and even deeper penetration. Depth of penetration is further enhanced by using a larger spot size (10 mm).
Neodymium: yttrium-aluminum-garnet (Nd:YAG) laser treatment has surfaced as an effective treatment for superficial venous malformations.
The Q-switched alexandrite laser is effective in tattoo removal of black, blue, and green inks. The Q-switched ruby laser is effective in removing tattoos with minimal scarring and removes black, blue-black, and green ink.
2012
A 42-year-old woman is scheduled to undergo facial resurfacing with a fractionated carbon dioxide laser. This procedure acts by targeting which of the following substances in skin?
A) Collagen B) Elastin C) Hyaluronic acid D) Melanin E) Water
The correct response is Option E.
The principle of selective photothermolysis as applied to skin resurfacing (ablation) is based upon water content. The epidermis is composed of 90% water and is vaporized at temperatures in excess of 212°F (100°C). The carbon dioxide laser has water as its chromophore. The carbon dioxide laser has a wavelength of 10,600 nm and has a water absorption coefficient of 800/cm.
The collagen, elastin, hyaluronic acid, and melanin content of skin may be affected by the temperature change from the laser energy, but water is the chromophore that is targeted by an ablative, fractionated carbon dioxide laser.
2011
A 45-year-old woman comes to the office because of a rash and a burning sensation on her face 1 week after undergoing carbon dioxide cutaneous laser resurfacing. Physical examination shows erythematous pustules on the right side of the face in the V3 distribution. Which of the following agents is the most appropriate treatment?
A ) Oral acyclovir B ) Oral cephalexin C ) Oral prednisone D ) Topical bacitracin E ) Topical petrolatum
The correct response is Option A.
The patient’s symptoms are consistent with a viral infection. Viral, bacterial, and fungal infections can develop after cutaneous laser resurfacing, usually at the time of the first postoperative week during the reepithelialization process. The most frequent infectious complication associated with resurfacing is a reactivation of the herpes simplex virus (HSV). It is suspected that direct laser trauma to the skin leads to latent viral activation and shedding. Herpetic outbreaks are experienced by roughly 2 to 7% of all laser-treated patients despite antiviral prophylaxis. In addition, due to the high incidence of latent HSV infection, any patient (regardless of prior HSV history) planning to undergo full-face or perioral resurfacing should be given oral antiviral prophylaxis in an effort to reduce viral reactivation, which could subsequently lead to scarring. Early postlaser detection of HSV is often difficult because there is no intact epithelium, and, rather than the characteristic grouped vesicles or pustules, infection is manifested by small, superficial erosions. Symptoms of HSV reactivation include tingling, burning, or discharge from isolated foci within the treated areas. Extensive eruptions can result in disseminated infection and atrophic scarring, and therefore, must be recognized early and treated aggressively. Oral antiviral agents, such as acyclovir, famciclovir, or valacyclovir, are routinely administered 1 to 2 days before the laser resurfacing procedure and are continued for another 7 to 10 days until reepithelialization is complete. If a herpetic outbreak occurs despite prophylaxis, patients should either be switched to a different antiviral agent or have their dosage increased to maximal herpes zoster doses (acyclovir 800 mg 5 times daily or famciclovir or valacyclovir 500 mg 3 times daily).
Cephalexin would be more appropriate for bacterial skin infections. Bacitracin does not have antiviral coverage. Topical petrolatum is a bland emollient and would not treat the HSV outbreak. Oral corticosteroids do not have any role in the treatment of viral infections.
2010
