Wl. Hoffman et al., CRYOGEN SPRAY COOLING DURING ND-YAG LASER TREATMENT OF HEMANGIOMAS - A PRELIMINARY ANIMAL-MODEL STUDY, Dermatologic surgery, 23(8), 1997, pp. 635-641
BACKGROUND. Successful laser treatment of hemangiomas requires selecti
ve photothermal destruction of dilated cutaneous vessels without damag
ing the overlying epidermis. Delivering a short cryogen spurt, on the
order of milliseconds, has been shown to result in localized cooling o
f the superficial skin structures during laser irradiation. OBJECTIVE.
The purpose of this study was to examine the effectiveness of cryogen
spray cooling (CSC) in protecting superficial tissue structures durin
g continuous Nd:YAG laser irradiation of an in vivo model hemangioma.
METHODS. The highly vascularized chicken comb was selected as the anim
al model for hemangiomas. The Nd:YAG laser irradiation ranged from 2.6
to 35.1 J/mm(2). A feedback system utilizing infrared radiometry moni
tored the comb surface temperature and controlled delivery time of the
cryogen spurt. When comb surface temperature during laser irradiation
reached 36-42 degrees C, a 30-100 msec cryogen spurt was delivered. A
nimals were euthanized 1 hour to 21 days following each experiment. Gr
oss and histologic analyses were performed. RESULTS. Nd:YAG laser irra
diation resulted in deep (up to 6.1 mm) tissue photocoagulation, while
CSC preserved the overlying epidermis and papillary dermis.CONCLUSION
. The results demonstrate that CSC is effective in protecting the epid
ermis and papillary dermis, while achieving deep tissue photocoagulati
on during Nd:YAG laser irradiation. Further pilot studies in humans ap
pear warranted. (C) 1997 by the American Society for Dermatologic Surg
ery, Inc.