Flashcards in Laser and Light Treatment of Acquired and Congenital Vascular Lesions Deck (141):
Lasers produce selective photocoagulation of vessels using wavelengths of light that are well absorbed by haemoglobin.
Lasers produce selective photocoagulation of vessels using pulse durations equal to or longer than the thermal relaxation time (or cooling time) of the vessels.
F Equal to or shorter than thermal relaxation time.
Larger-diameter and deeper vessels require shorter wavelengths of light and shorter pulse durations.
F Longer wavelength and longer pulse durations.
Lasers and light devices used to treat vascular lesions include KTP, pulsed-dye, alexandrite, diodie and Nd:YAG lasers, in addition to IPL.
Laser stands for Light Amplification by the Stimulated Emission of Radiation.
Fluence is measured in J/cm2.
The major chromophores in skin are haemoglobin and melanin.
F And water.
When targeting a vascular lesion, the wavelength of light chosen should be well absorbed by haemoglobin and poorly absorbed by melanin.
Selective heating of the laser target is produced when the energy is deposited at a rate faster than the rate for cooling of the target structure.
Pulsed KTP laser has a wavelength of 532nm.
Pulsed dye laser has a wavelength of 595nm.
F 585nm (long-pulsed dye is 585-600nm).
Long-pulsed alexandrite laser has a wavelength of 755nm.
Diode laser uses 800, 810 or 840nm wavelength.
F 800, 810 or 940nm.
Long-pulsed Nd:YAG laser has a wavelength of 1064nm.
IPL uses a wavelength of 515-920nm.
For a given wavelength of light, the optical penetration into skin depends on absorption and scattering.
The most penetrating wavelengths are in the 650-1200nm red and near-infrared region.
Longer wavelengths (600-1200nm) penetrate deeper, but with more scattering
F Deeper with less scattering
The least penetrating wavelengths are in the far UV, where protein absorption dominates, and the far-infrared, where water absorption dominates.
The depth of penetration gradually decreases with longer wavelengths.
F Increases with longer wavelengths.
With smaller spot sizes, a greater fraction of photons scatter outside the beam area and are rendered ineffective.
Cooling the skin does not effect tissue injury caused by laser procedures.
F Cooling before/during/after reduces tissue injury.
Cooling can be achieved by using a liquid cryogen spray during treatments
Pulsed-dye laser produces transient blue-black purpura due to haemorrhage and a delayed vasculitis.
For v essels 10-50microm in diameter, the thermal relaxation time would be 0.1-10ms, with an average of 1.2ms
Pulsed-KTP lasers emit in the green light spectrum.
Longer pulse durations increase photomechanical injury and post-treatment purpura.
Lasers with near-infrared wavelengths are not suitable for treating larger vascular anomalies or larger leg veins.
F Alexandrite, diode and Nd:YAG used for this.
Vascular lasers can be used for capillary malformations, haemangiomas, venous malformations, telangiectasias, facial erythema, cherry angiomas, venous lakes and poikiloderma of Civatte.
Striae distensae cannot be treated with vascular laser.
F Striae rubra shows best response.
The hypopigmentation of striae distensae responds well to vascular laser.
F No effect.
Port wine stains can regress.
F Never regress.
Port wine stains darken in colour and become increasingly nodular with age.
The hypertrophy or nodularity of a PWS are associated with a risk of spontaneous bleeding or haemorrhage with injury to the site.
PWS should not be treated ideally until adulthood.
F Childhood better.
Treatment of PWS in early life enables more rapid clearing, however there may be partial return of the PWS 5-10 years after treatment.
Greater PWS clearance in children is attributed to thinner skin allowing better laser penetration, smaller vessel diameter, and smaller lesional surface area.
Gradual clearing of PWS is produced with successive PDL treatments usually performed at 2-4 week intervals.
F 4-6 week intervals.
PDL can be safely used in skin types I-IV.
With PDL, longer wavelengths and longer durations improve PWS clearance.
T Longer wavelengths provide more deeply penetrating light to target deeper vessels.
The response of a PWS to PDL treatment depends on its size, anatomic location and the types of vessels that comprise the lesion
PWS that are present in the central facial area or in a V2 dermatomal distribution respond faster than PWSs located elsewhere on the head and neck.
F More slowly.
PWS on extremities respond more slowly to laser therapy than lesions on the trunk, and lesions on the distal extremity respond the slowest.
Smaller PWSs respond better to PDL.
The best response to PDL is seen in PWSs located deeper, with smaller diameter vessels.
F Superficially located, larger-diameter vessels
Vessel morphology does not correlate with PWS colour.
F Pink = smaller vessel, purple = larger vessel.
Red PWS lesions are composed of more superficially located vessels than pink or purple ones.
Red coloured PWSs respond poorly to laser, while pink coloured PWSs respond better.
F Red better, pink worse.
Even slowly responsive PWSs continue to clear with repetitive PDL treatment with no increased risk of adverse effects.
PDL treatment for PWS during infancy is not recommended.
F Safe and rapid clearance possible.
Treatment of PWS with PDL is usually performed with the smallest spot size available to prevent reticulation.
F Largest spot size.
PDL treatment of PWS should be performed with the lowest fluence possible that produces purpura without tissue graying or whitening.
Improved technology in skin cooling has been a major advancement in treatment of PWS
Appropriate cooling can be achieved by applying millisecond-duration cryogen spurts, preceding each laser pulse with maintenance of the temperature of the laser-heated dermal vessels
There may be a delayed final tissue reaction after PDL, so the patient should be observed for several minutes after treatment.
Intense purpura develops 7-10 days after PDL.
The post-treatment purpura associated with PDL takes 2-4 weeks to resolve.
F 7-10 days.
Following resolution of purpura after PDL, lesional lightening takes place over 4-8 weeks, when repeat treatments are performed.
Subsequent treatment sessions with PDL should be delayed until all traces of relative erythema have subsided.
Treatment should be performed with the lowest possible fluence that produces purpure without tissue graying or whitening
When tissue graying is encountered, skin should be cooling immediately with ice-packs to avoid epidermal necrosis, crusting and potential scarring
Subsequent treatment sessions for PWS can continue despite the development of reactive erythema
F Should be delayed until all traces of reactive erythema have subsided
IPL devices are broadband filtered xenon flashlamps that work on the principles of selective photothermolysis.
The IPL emission spectrum of 515-1200nm is adjusted with the use of a series of cut-off filters.
The pulse duration of IPL ranges from approximately 100 to 200ms.
F 0.5 to 100ms
IPL is the treatment of choice for PWS.
IPL can be used to treat PDL-resistant PWS.
KTP laser provides relatively equal absorption and depth of penetration to the PDL, but the overall rate of side effects is higher due to its higher absorption by melanin.
Long-pulsed alexandrite and Nd:YAG lasers are effective in treating hypertrophic or nodular PWS.
The alexandrite laser can produce bulk heating and necrosis if used too aggressively for the treatment of PWS.
F This is true for Nd:YAG.
The Nd:YAG laser has a higher incidence of post-inflammatory hyperpigmentation compared to the PDL.
F This is true for the alexandrite laser.
Haemangiomas occur in females three times as often as males.
60-70% of haemangiomas occur on the trunk.
F Head and neck.
Haemangiomas are composed of numerous small blood vessels and infiltrating vascular endothelial cells that express GLUT1.
Infantile haemangiomas initially appear as white or pink macules, or telangiectasia with surrounding vasoconstriction.
Approximately 5% of patients with haemangiomas have incomplete involution.
Superficial haemangiomas appear as bright red vascular papules or plaques when fully developed.
Deep haemangiomas appear as bluish-coloured nodules within the skin with only a subcutaneous component.
Haemangiomas may be only either superficial or deeply located.
F Compound haemangiomas occur.
Focal haemangiomas account for 85% of lesions.
Focal haemangiomas occur on any site in random distribution.
F Occur along lines of embryological fusion.
Diffuse hamangiomas occur on any body site in random distribution.
F Segmental distribution.
Diffuse haemangiomas tend to be deep lesions.
F Superficial or compound.
Diffuse haemangiomas carry a high risk of ulceration.
Laser therapy for haemangiomas can only be performed once the lesion has involuted.
F Perform during both proliferation and involution.
PDL prevent haemangioma enlargement, promote involution, induce re-epithelialisation of ulcerations, and reduce ectasia.
Thin haemangiomas (
Haemangiomas treated early in the prodromal phase respond better than those treated during active proliferation.
Laser treatment usually slows the proliferation of the superficial component of haemangiomas and promotes early regression.
Haemangiomas should be treated using the same laser parameters as for PWS.
F Lower fluence, larger spot size.
Ulceration is not a common complication of haemangiomas.
F Most common complication.
Approximately 12% of diffuse haemangiomas and 65% of focal haemangiomas ulcerate.
F 12% focal, 65% diffuse.
Ulcerated haemangiomas usually result in a scar.
Ulcerated haemangiomas respond well to PDL if the ulceration is limited and the haemangioma is not undergoing rapid proliferation.
Segmental haemangioms are best treated in the early growth phase with PDL.
F Laser can cause ulceration in this context.
Pulsed-dye lasers can greatly effect the subcutaneous component of haemangiomas.
F Little effect due limited depth of penetration.
CO2 lasers and long-/short-pulsed Er:YAG lasers produce excellent improvement in the atrophic scarring and textural change that accompany haemangioma involution.
The peak incidence of spider angiomata between the ages of 30 and 40 years old.
Treatment of telangiectasiae with PDL is performed by applying contiguous laser pulses with no overlap.
F Approx. 10% overlap.
Nd:YAG can be very safely used around the nasal ala to treat telangiectasiae.
F Need proper skin cooling and avoidance of pulse stacking to prevent epidermal damage.
Long-pulsed Nd:YAG lasers are particularly useful for the treatment of larger-calibre paranasal vessels.
Nd:YAG treatment of visible facial veins is limited to those outside the orbital rim.
T Risk of damage to eye with this deeply penetrating wavelength.
IPL cannot be used to treat facial telangiectasiae.
Laser treatment of poikiloderma should be delayed for a minimum of 4 weeks following sun exposure.
Compared to the treatment of telangiectasia, fluences for poikiloderma should be lowered by approximately 50-70% to avoid adverse effects.
IPL systems for the treatment of poikiloderma generally use 515-550nm cut-off filters.
During IPL treatment, a thin layer of gel is applied to the skin surface to aid in skin cooling.
Erythema and oedema may be present for 2-3 weeks following laser or IPL treatment of poikiloderma.
F 2-3 days.
PDL is not suitable for the treatment of scars.
F Use for erythematous and hypertrophic scars.
PDL treatment for scars reduces erythema, scar height and surface texture changes.
Multiple PDL treatment sessions are often necessary for scars.
Scars should be treated with lasers in intervals of 6-8 weeks.
PDL are not very effective in treating condyloma acuminata, plantar warts, periungual wart, flat warts and verrucae vulgaris.
Recalcitrant warts post-laser treatment are best treated with a different method.
F Require 3-4 treatments at 3-4 week intervals.
Laser and IPL beams should always be directed away from the orbit when treating in the eye region.
PDL is capable of igniting a fire in the presence of oxygen and nitrous oxide.
Topical anaesthetic cannot be used with vascular lasers and light sources.
With PDL, larger spot sizes are less efficacious and increase the potential for reticulation.
F Greater efficacy, reduce potential for reticulation between Rx sessions.
With PDL, post-treatment purpura is most intense with the 0.45ms pulse duration and requires approx. 10 days for resolution.
With epidermal cooling techniques, blistering or crusting after PDL occurs rarely.
At pulse durations greater than 6ms, purpura is not produced with PDL.
T Urticarial papules resolve over several hrs.
Most vascular lesions only require one treatment session.
F Multiple Rx sessions.
Suntanned individuals can be treated with PDL and KTP laser.
F Risk of absorption by epidermal pigment.
Facial telangiectasia and erythema respond well to millisecond-duration KTP lasers.
Patients with skin types V and VI can be treated with KTP laser.
Following treatment with KTP laser, there may be erythema and urticarial oedema of the treated skin lasting up to 24 hours.
Scarring can occur after KTP laser due to excessive fluence, overlapping of laser pulses, or in adequate skin cooling, which results in non-selective thermal damage to the epidermis/dermis.
Nd:YAG laser is the first-line device for treatment of superficial telangiectasia-
Larger paranasal and periauricular telangiectasia and venulectasia, that may not clear with green and yellow light, don’t respond well to Nd:YAG laser.
F Do respond well due to its greater depth of penetration.
The Nd:YAG laser produces bulk tissue heating.
Nd:YAG laser pulses can be safely stacked.
F Never – leads to ulceration and necrosis.
IPL uses a large rectangular footprint.
With IPL, shorter wavelength filters (515nm) and the single pulse mode are used on skin type I with fine superficial vessels.
With IPL, larger and deeper vessels are treated with longer cut-off filters (570 and 590nm) and double or triple pulse modes.
With IPL, shorter wavelength and shorter interpulse delays are used for darker skin types.
F Longer wavelength and interpulse delay.
Gel is not needed when treating with IPL.
Pulse durations of 10ms or higher are generally required to avoid purpura formation.
In contrast to treatment for telangiectasia, fluences should be lowered by 25-30% to avoid adverse effects in treating poikiloderma
PDL can be applied to treat hypertrophic scars but have a poor response
T good response (57-83%)
Pulsed dye lasers are very effective in treating the cutaneous lesions of HPV
T Via thermal alteration of the virally infected tissue