Dynamic skin cooling with an environmentally compatible alternative cryogen during laser surgery

Area of Science:

• Dermatology
• Laser Surgery
• Cryogenics
• Environmental Science

Background:

• Tetrafluoroethane (R134a) is utilized for epidermal cooling during laser surgery but possesses a high global warming potential (GWP=1300).
• A need exists for alternative cryogens with reduced environmental impact for dermatologic procedures.

Purpose of the Study:

• To assess the cooling effectiveness of liquid carbon dioxide (CO(2)), a cryogen with a low GWP (1), as an alternative to R134a.
• To compare the cooling performance and physical properties of CO(2) and R134a sprays.

Main Methods:

• Surface temperature (T(s)) measurements on an epoxy skin phantom using thin-film thermocouples.
• Estimation of temperature distribution via T(s) and Duhamel's method.
• Measurement of impact pressure, noise level, and cryogen consumption for both R134a and CO(2) sprays.

Main Results:

• CO(2) sprays achieved lower minimum surface temperatures than R134a sprays with spurt durations exceeding 35 milliseconds.
• Numerical simulations indicated comparable temperature reductions between CO(2) and R134a with optimized spray parameters.
• CO(2) sprays exhibited higher impact pressure (43.1 kPa vs 3.6 kPa) and noise levels (135 dBA vs 109 dBA) but lower GWP than R134a.

Conclusions:

• Liquid carbon dioxide (CO(2)) demonstrates comparable skin cooling efficacy to tetrafluoroethane (R134a) for dermatologic laser surgery.
• Despite higher consumption, CO(2)'s significantly lower global warming potential presents a more environmentally sustainable option.
• Further research is needed to evaluate in vivo effects on human skin and cutaneous blood flow.