Riverside, Calif. — A new study suggests that during laser irradiation using devices that administer cooling cryogen spray, the device’s nozzle can produce an uneven spread of liquid cryogen, which results in zones of high and low heat extraction, reports HealthDay News. The risk of thermal injury occurs at the periphery of the laser beam, away from the cooling tip, where heat extraction is lowest.
Researchers from the University of California, Riverside, used a 755 nanometer laser to assess the ability of cryogen spray cooling to protect the lateral epidermis. They found that the safest therapy occurred with a 10-mm diameter beam because only the zone of highest heat extraction was exposed to laser irradiation.
“Therefore, there is risk of thermal injury at the beam periphery when there is a mismatch between the skin protected by cryogen spray cooling and that exposed to laser irradiation,” the authors conclude. “For the cooling and irradiation sequences considered [in this study], heat extraction provided by a 60 milliseconds spurt with 30 milliseconds delay correctly matches the heating profile of a 10-mm diameter beam.”
The study’s findings appear in the June issue of Lasers in Surgery and Medicine.
