Laser in plastic Flashcards
laser therapy for hypertrophic burn and
trauma scars has led to significant improvements
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Photothermal events represent the majority ofmedical laser reactions
and result from an increase oflocal kinetic energy and the generation
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Photomechanical reactions result in structural degradation ofthe chromophore
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Photochemical reactions occur when
the excited state ofthe chromophore has markedly different physical
or chemical properties than the resting state.
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absorption spectrum
ofthe chromophore and its location within the skin. These two factors
will determine the wavelength of the laser medium
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the wavelength selected should minimize collateral injury that could
result in dyspigmentation
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The pulse width should not exceed the TRT
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Increasing the laser spot size allows for more rapid
treatment sessions and a decrease in the relative scatter of light.
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if the spot size is increased, the fluence will likely need to be increase
F if the spot size is increased, the fluence will likely need to be decreased to prevent excessive energy delivery
rate in which pulses
are delivered, is also important to consider in order to avoid excessive
bulk heating.
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treatment of cutaneous vasculature by laser the affect of laser it will be in form of photochemical reaction
F PHTOTHERMAL
Oxyhemoglobin displays an absorption band from 400 to 1200 nm
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Deoxyhemoglobin demonstrates an absorption peak that includes the 755 and 800 nm wavelengths.
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patients with higher FSTs, longer wavelength lasers
should be utilized
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When selecting a pulse width, titrate to the target
(blood vessel) and not the chromophore (hemoglobin)
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Fully ablative lasers targeting water as a chromophore
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Fully ablative lasers may also be used to nonselectively destroy vasculature in the treatment area.
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Without treatment, 65% of
PWSs become hypertrophic, often leading to bleeding, aesthetic
deformation, and psychological stress
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Port winr stiane in children need to treated with longer wavelength lasers
F In infants and
young children, PWSs are erythematous with increased oxyhemoglobin and respond well to shorter wavelength lasers
PWSs in adult
patients are often more violaceous owing to deoxyhemoglobin and
demonstrate increased thickness necessitating use of the longer
wavelength lasers.
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Initiating treatment as early as possible is critical for minimizing laser light scatter due to dermal collagen and
acquired tanning melanin
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selective photothermolysis can be used for all type of haemangioma
F Superficail and ulcerated as
well as resolved hemangiomas with residual vasculature
Endovenous laser ablation represents the gold standard in the management oflarger varicosities
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After successful endovenous laser ablation, spider
veins may be treated with sclerotherapy or vascular laser treatment
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In telangiectasias Optimal treatment includes longer pulse widths and the end point of
durable purpura
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Shorter pulse widths and subpurpuric fluences have been
shown to achieve ideal outcomes in generalized erythema.
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short millisecond pulse widths may be used with purpuric
fluences can be use in treatment of angioma
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Treatment of warts using laser therapy has demonstrated equivocal
outcomes to cryotherapy or electrodessication
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vascular lasers
are capable of destroying wart vasculature.
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Purpuric settings should
be used without epidermal cooling. in treatment of wart
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Selective photothermolysis significantly reduce postprocedural purpura
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risk ofscarring is much
greater with the infrared lasers in PWS
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The absorption spectrum of melanin is inversely proportional to laser light wavelength
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In patient
populations with increased physiologic melanin, longer wavelengths
should be selected in order to. avoid dyspigmentation
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Fractional and fully ablative lasers targeting water as a chromophore may also be used to nonselectively destroy pigment
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Devices commonly used
to target melanin in
the long-pulsed, short-pulsed, and ultrashort-pulsed domains
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Epidermal melanine treated with photothermal reaction
F Once melanin absorbs laser light, the ensuing
photoreaction may be photothermal or photomechanical depending upon the pulse width selected
shorter wavelength lasers
may demonstrate efficacy as the pigment resides in the epidermis in Cafe-au-lait Macules
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small, excision may represent a better treatment option for cafe-au-lait Macules
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Ephelidesalso demonstrateincreased mwlanocyte in the epidermis
F increased melanin in the epidermis
In FST I to III patients, the long-pulsed alexandrite is the
laser for hai removal
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In FST IV to VI patients, the long-pulsed Nd:YAG laser is preferred for the effective removal of hair while sparing melanin within the skin
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longer
wavelengths are often utilized melanocytes are present in the dermis
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1064 nm Nd:YAG laser in the nanosecond domain was more efficacious and better tolerated than the nanosecond 755 nm alexandrite laser in dermal melnocyte
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Laser therapymay permenantly lighten melasma,
F Laser
therapymay temporarily lighten melasma, butit is often recurrent and
may be exacerbated by light therapy
Sun avoidance and
serial superficial chemical peels can often achieve patient satisfaction
with less risk for rebound hyperpigmentation for Melasma
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Short-pulsed and ultrashort-pulsed lasers in the 700
to 1064 nm range have shown some efficacy in improving Drug-Induced Pigmentation
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Laser treatment of PIH is rarely pursued,
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Sun avoidance and topical bleaching agents can improve
PIH significantly
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short-pulsed and ultrashort-pulsed lasers are the pulse widths ofchoice for remova Tattoo Pigment
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photothermal and photomechanical reactions cause
the tattoo particles to be broken down
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In the case ofmulticolor tattoos, treatment should be performed
with the most superficial (shortest) wavelength first
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Patients with
higher FSTs should be treated with caution, as shorter wavelengths of
light are highly absorbed by melanin.
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growing number oflaser surgeons advocate for treating over
the tattoo with ablative fractional laser (AFL) to allow the release of
cutaneous edema and to provide a potential path for the extravasation
oftattoo remnants
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Treatment intervals should be at least 3 weeks in
length to allow for mobilization oftattoo pigment
F 6
15 treatments
with short-pulsed (nanosecond) lasers result in only 75% of patients
experiencing successful tattoo removal.
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The newer ultrashort-pulsed
(picosecond) lasers have anecdotally cleared tattoos faster and with
fewer treatments
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AB laserlight wavelength increases, absorption ofelectromagneticradiation by hemoglobinandmelanindiminish while theabsorptionby water
increases
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Depending upon the wavelength of light, the ensuing tissue interaction may be thermal (nonablative) or ablative
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The continuous wave CO2
laser was the first to ablate successive layers of tissue in order to treat
rhytidosis, dyschromia, and rhinophyma and to remove focal skin
growths
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pulse widths less than the TRT can avoid the complicatoin of ablative laser
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Laser of fully ablative resurfacing co2 laser and Er:YAG
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thermal injury
from the CO
2 laser results in greater long-term skin contraction
and fibroplasia
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The
increased depth of penetration afforded by fractional photothermolysis hasdemonstrated unique benefit when treating hypertrophic and
keloid scars.
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Ablative fractional laser (AFL) was found to be beneficial in the
treatment of burn and trauma scars
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laryngeal papillomatosis
caused by aerosolized viral particles in laser-generated smoke
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