Cryogen spray cooling during Nd:YAG laser treatment of hemangiomas. A preliminary animal model study.
BACKGROUND
Successful laser treatment of hemangiomas requires selective photothermal destruction of dilated cutaneous vessels without damaging the overlying epidermis. Delivering a short cryogen spurt, on the order of milliseconds, has been shown to result in localized cooling of 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 during continuous Nd:YAG laser irradiation of an in vivo model hemangioma.


METHODS
The highly vascularized chicken comb was selected as the animal model for hemangiomas. The Nd:YAG laser irradiation ranged from 2.6 to 35.1 J/mm2. A feedback system utilizing infrared radiometry monitored 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. Animals were euthanized 1 hour to 21 days following each experiment. Gross and histologic analyses were performed.


RESULTS
Nd:YAG laser irradiation resulted in deep (up to 6.1 mm) tissue photocoagulation, while CSC preserved the overlying epidermis and papillary dermis.


CONCLUSIONS
The results demonstrate that CSC is effective in protecting the epidermis and papillary dermis, while achieving deep tissue photocoagulation during Nd:YAG laser irradiation. Further pilot studies in humans appear warranted.
Hoffman
W L
WL
Department of Dermatology, University of California, Irvine 92612, USA.
Anvari
B
B
Said
S
S
Tanenbaum
B S
BS
Liaw
L H
LH
Milner
T
T
Nelson
J S
JS
D000336:Aerosols; D000538:Aluminum Silicates; D000818:Animals; D002645:Chickens; D005617:Chlorofluorocarbons, Methane; D003129:Comb and Wattles; D017679:Cryotherapy; D062109:Dermatologic Surgical Procedures; D004108:Dilatation, Pathologic / Q000601:surgery; D004195:Disease Models, Animal; D004817:Epidermis / Q000473:pathology / Q000601:surgery; D005246:Feedback; D005500:Follow-Up Studies; D006391:Hemangioma / Q000098:blood supply / Q000601:surgery*; D007259:Infrared Rays; D017075:Laser Coagulation; D016343:Monitoring, Intraoperative; D009354:Neodymium; D010865:Pilot Projects; D011874:Radiometry; D012867:Skin / Q000098:blood supply / Q000473:pathology; D012878:Skin Neoplasms / Q000098:blood supply / Q000601:surgery*; D012881:Skin Temperature; D015019:Yttrium
D000336:Aerosols; D000538:Aluminum Silicates; D005617:Chlorofluorocarbons, Methane; D009354:Neodymium; D015019:Yttrium; C009755:fluorocarbon 22