Laser 01-22 Flashcards
An 18-year-old woman with Fitzpatrick type IV skin presents for carbon dioxide laser treatment for hypertrophic scarring 1 year after sustaining facial burns. Two weeks after the first session, hypopigmentation is noted in the laser-treated areas. Which of the following adjustments to the laser setting is most likely to prevent further hypopigmentation from occurring after the next session?
A) Decreasing the dwell time
B) Decreasing the spot size
C) Increasing the dwell time
D) Increasing the energy
E) Increasing the spot size
The correct response is Option A.
Patients classified as higher Fitzpatrick types have a higher risk for hypopigmentation after carbon dioxide laser therapy. For example, punctate hypopigmentation has been found in up to 35% of facial burn patients presenting 2 months after being treated with fractionated carbon dioxide laser therapy. To decrease the risk for further hypopigmentation, the dwell time needs to be decreased. Increasing the dwell time prolongs the time of exposure, increasing the risk for hypopigmentation. Increasing or decreasing the spot size only increases or decreases the surface area treated. Increasing the energy would also increase the risk for hypopigmentation.
A 21-year-old woman with Fitzpatrick Type V skin presents for evaluation of acne scarring. Treatment with a fractional nonablative laser is planned. Which of the following lasers is most appropriate to treat acne in this patient?
A) Carbon dioxide (10,600 nm)
B) Erbium-doped fiber (1550 nm)
C) Erbium:YAG (2940 nm)
D) Erbium:YSGG (2790 nm)
The correct response is Option B.
Nonablative fractional lasers are commonly used for acne scar resurfacing in darker skin types. Nonablative lasers work by denaturation of dermal collagen with subsequent remodeling, without any vaporization or damage to the epidermis.
Erbium-doped fiber laser (1550 nm) is a nonablative laser while Erbium:YAG (2940 nm), carbon dioxide (10,600 nm), and Erbium:YSGG (2790 nm) are ablative lasers.
A 58-year-old woman plans to undergo Er:YAG laser resurfacing (2940 nm) to improve the appearance of perioral rhytides. The procedure targets which of the following?
A) Collagen
B) Elastin
C) Hemoglobin
D) Melanin
E) Water
The correct response is Option E.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.
Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12- to 16-fold greater than carbon dioxide laser. Targeting hemoglobin would not be appropriate since this will not lead to rejuvenation of perioral rhytides. The treatment of melanin is not the correct target since this would only lead to hypopigmentation or absorb the laser wavelength and lead to a possible burn. Collagen and elastin are essential elements of maintaining a youthful dermis; these dermal proteins are not the target of lasers, but rather induced by the trauma occurring from the laser itself.
A 54-year-old man with Fitzpatrick type II skin is scheduled to undergo photoaging treatment with a carbon dioxide fractional laser. Which of the following measures is most likely to decrease this patient’s risk of hypertrophic scarring?
A) Decreasing fluences
B) Heat stacking
C) Increasing surface area coverage
D) Treating the neck skin
E) Using multiple laser passes
The correct response is Option A.
Fractional laser resurfacing of photo-damaged or acne-scarred skin has supplanted traditional carbon dioxide ablative laser devices while diminishing the incidence of adverse effects and effecting a more rapid recovery. However, hypertrophic scarring (HTS) is a noteworthy complication that requires the utilization of preventive measures to minimize its occurrence. Conservative treatment of the neck is foremost among these measures. Use of lower fluences (energy density, defined as Joules/cm2) treating reduced surface areas, abstinence from heat stacking, and avoiding multiple passes by a carbon dioxide laser all contribute to less incidence of HTS. Patient selection, preoperative education, and preparation for treatment of this complication are appropriate adjunctive measures as well.
A 27-year-old woman presents with a multicolored decorative tattoo on her leg. She is interested in laser tattoo removal. On physical examination, over 80% of her tattoo has red and orange colors. Which of the following laser treatments would be most effective on the orange and red areas?
A) 755-nm Q-switched alexandrite
B) 532-nm Q-switched Nd:YAG
C) 1064-nm Q-switched Nd:YAG
D) 694-nm Q-switched ruby
The correct response is Option B.
Successful tattoo removal can be performed using different types of laser wavelengths. The 532-nm Q-switched Nd:YAG would be used for targeting red, yellow, and orange color tattoos. Black pigments can be effectively removed with Q-switched Ruby 694-nm, 755-nm Alexandrite, or 1064-nm Nd:YAG lasers. Purple ink responds best to the Q-switched 694-nm ruby laser and green ink best removed with the Q-switched 755-nm Alexandrite laser. The Q-switched Ruby 694 nm laser creates a red light that is highly absorbed by green, blue, and dark tattoo pigments.
A 58-year-old woman with a history of rosacea is scheduled to undergo Er:YAG laser resurfacing to improve the appearance of perioral rhytids. When compared with a carbon dioxide laser, for which of the following does the Er:YAG laser have a greater affinity?
A) Hair follicle
B) Hemoglobin
C) Melanin
D) Papillary dermis
E) Water
The correct response is Option E.
Use of nonsurgical skin rejuvenation has increased exponentially over the past 20 years, with over 4.6 million cases performed annually. This increase has led to expansion of different types of devices for resurfacing. The use of lasers for facial resurfacing has been discussed since the 1980s, initially with carbon dioxide lasers and then with erbium-doped yttrium aluminium garnet (Er:YAG) lasers in the late 1990s. Ablative laser treatments have been used to target actinic skin damage and moderate to heavy rhytides.
Lasers work by means of a wavelength of light being absorbed by specific targets (chromophores) in the tissue, causing thermal damage. The targeted chromophore absorbs energy, which is converted to heat. Tissues that are heated to 60° to 70°C (140°F to 158°F) coagulate; above 100°C (212°F), vaporization occurs. The carbon dioxide laser has a wavelength of 10,600 nm with a target chromophore of water. In the mid 1990s, the ability to deliver increasing power over shorter amounts of time allowed temperatures to be reached that would allow ablation of the epidermis. However, even with ablation there was a zone of coagulation surrounding the ablation that ranged between 70 and 120 ?m. The Er:YAG laser has a wavelength of 2940 nm. The peak absorption of water is nearly 2900 nm, which means that an Er:YAG laser has an absorption 12 - to 16-fold greater than carbon dioxide laser. Because of this unique feature, the ablation threshold of Er:YAG is only 1 J/cm2 compared with the carbon dioxide laser’s ablation threshold of 5 J/cm2. The clinical relevance is that a much higher percentage of targeted tissue is ablated rather than heated, so that the resultant surrounding coagulation zone is only 5 to 20 ?m of tissue.
It is a common mischaracterization of full-field resurfacing options to state that “erbium is more superficial than carbon dioxide.” This is only true for a single pulse and equivalent energies, as the erbium wavelength is rapidly absorbed in water at a rate 11 to 16 times higher than carbon dioxide. However, such a statement is contrary to the fact, as erbium allows ablation of the dermis and the epidermis, unlike carbon dioxide, which can only ablate epidermis. Erbium can easily ablate the dermis on successive pulses until the skin, muscle, and even bone can be totally obliterated. Carbon dioxide can only affect deep tissue by stacking pulses and creating “bulk heat” that melts the tissue rather than ablating, and is both imprecise and dangerous.
Erbium provides a controlled depth of ablation with a minimal underlying thermal zone of coagulation. This decrease in thermal injury leads to a faster recovery following erbium laser ablation compared with carbon dioxide laser. The smaller coagulative zone results in a lower rate of hypopigmentation and allows for a more controlled depth with each pass. Carbon dioxide lasers can have variable depth of penetration, especially after the first pass when the dermis is exposed, and the residual thermal injury creates a “char,” which becomes thicker with each pass, making penetration increasingly difficult.
A healthy 48-year-old woman comes to the office for consultation regarding laser resurfacing of fine facial wrinkles in the perioral region. Her skin color is light brown and she states that she rarely gets sunburned (Fitzpatrick Type IV). Examination shows rhytides in the perioral region, on the forehead, and in the lateral canthal region. Compared with a patient who has a lighter skin color (Fitzpatrick Type I-III), which of the following is this patient at increased risk for after laser resurfacing in the perioral region?
A) Freckles
B) Herpetic lesions
C) Hypertrophic scars
D) Post-treatment hyperemia
E) Postinflammatory hyperpigmentation
The correct response is Option E.
Understanding the potential complications after facial resurfacing is important to know, especially those complications that occur in patients with darker skin. Traditionally, the Fitzpatrick Scale is used to assess skin tone and risk for both the development of skin cancer and also response to post-treatment pigmentation issues. Herpetic lesions can develop in individuals with any skin color after laser treatment. While hyperemia can develop in any patient after laser resurfacing, post-inflammatory hyperpigmentation is of greatest concern in those with darker skin color, especially in an individual like the one described, who has a Fitzpatrick Type IV skin type. While there are different ways to mitigate the issue of pigmentation both before and after treatment, it is a risk factor that should be discussed with patients undergoing skin resurfacing, especially in darker skin individuals. Laser therapy has been used to treat hypertrophic scars and freckles.
A 30-year-old woman of Nordic heritage is interested in laser hair removal of “peach fuzz” on the upper lip. She has Fitzpatrick Type I skin and is very fair, with light blonde hair and blue eyes. Which of the following is the most appropriate technique for hair removal for this patient?
A) Alexandrite laser (755 nm)
B) Electrolysis
C) Intense pulsed-light
D) Long-pulse ruby laser (694 nm)
E) Nd:YAG laser (1064 nm)
The correct response is Option B.
Laser hair removal targets the melanin in the hair follicle. It is not useful in fair-haired patients who have low levels of melanin in their hair follicles.
Although all the devices listed here have been employed for hair reduction, only electrolysis would be likely to work in this patient.
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.
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.
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.
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.
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.
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.
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.
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.
Which of the following laser wavelengths is ideal for treating the lesion shown above?
(A) 532 nm
(B) 585 nm
(C) 788 nm
(D) 810 nm
(E) 2940 nm
The correct response is Option B.
The patient depicted in the photograph has a port-wine stain in the VBIII distribution of the trigeminal (V) nerve. These lesions may occur anywhere on the body but are most commonly seen on the face. They occur unilaterally in 85% of patients and involve more than one dermatome in almost 70% of patients. These lesions are more commonly seen in women than in men (3:1) and may be hereditary (25%). The natural progression of these lesions with age includes darkening of the lesion due to the presence of deoxyhemoglobin, with thickening of the dermis and a cobblestoning appearance. It should be noted that as the lesions get darker, they are more difficult to treat. Because of its depth, penetration, and specificity for vascular targets, the 585-nm laser is the best treatment choice for these lesions. Treatment with the pulsed-dye laser typically results in less epidermal injury and risks for scarring. It should be used with caution in patients with pigment.
The 532-nm laser (KTP) is useful for superficial vascular telangiectasis. Both the 788- and 810-nm lasers are useful for pigmentation as well as hair removal. Finally, the 2940-nm laser (erbium) is a resurfacing device and is not specific for vascular targets.
A 23-year-old woman has carbonaceous material embedded in the skin after sustaining injuries in a combustion accident at work. A photograph is shown above. Which of the following is the most appropriate management?
(A) Carbon dioxide laser therapy
(B) Nd:YAG laser therapy
(C) Deep dermabrasion
(D) Wide local excision and coverage with a thin split-thickness skin graft
The correct response is Option B.
In patients who have certain types of foreign material embedded in the skin, especially road asphalt, carbonaceous material, or ink from amateur tattoos, the most appropriate method of removal is multiple treatments with the Nd:YAG laser.
In the past, traumatic tattoos were removed with mechanical abrasive techniques, including dermabrasion, salabrasion, and the rubbing of table salt into the skin, each of which produced satisfactory results in superficial tattoos. However, better results have recently been demonstrated with laser therapy, which involves the removal of successive layers of skin to expose the intradermal pigment, which is subsequently vaporized.
The surgeon should take great care while administering Nd:YAG laser treatments in any patient who has sustained injuries resulting from a gunpowder or fireworks accident, as the unburned, embedded gunpowder can actually combust during treatment, leading to unacceptable scarring.
Although laser therapy is the treatment of choice for traumatic tattoos, the carbon dioxide laser is not recommended because it does not effectively remove embedded carbonaceous material. In addition, this laser has no selective absorption; as a result, epidermal structures are injured more easily and scarring is increased.
Deep dermabrasion and wide local excision combined with thin split-thickness skin grafting are excessively invasive procedures that will yield poor cometic results.
