Lasers in Surgery and Medicine 46:791–795 (2014) In Vivo Laser Cartilage Reshaping With Carbon Dioxide Spray Cooling in a Rabbit Ear Model: A Pilot Study

Background/Objectives: Similar to conventional cryogen spray cooling, carbon dioxide (CO2) spray may be used in combination with laser cartilage reshaping (LCR) to produce cartilage shape change while minimizing cutaneous thermal injury. Recent ex vivo evaluation of LCR with CO2 cooling in a rabbit model has identified a promising initial parameter space for in vivo safety and efficacy evaluation. This pilot study aimed to evaluate shape change and cutaneous injury following LCR with CO2 cooling in 5 live rabbits. Study Design/Materials andMethods: The midportion of live rabbit ears were irradiated with a 1.45mm wavelength diode laser (12J/cm) with simultaneous CO2 spray cooling (85millisecond duration, 4 alternating heating/ cooling cycles per site, 5 to 6 irradiation sites per row for 3 rows per ear). Experimental and control ears (no LCR) were splinted in theflexedposition for 30days followingexposure. A total of 5 ears eachwere allocated to the experimental and control groups. Results: Shape change was observed in all irradiated ears (mean 70 38), which was statistically different from control (mean 37 118, P1⁄4 0.009). No significant thermal cutaneous injury was observed, with preservation of the full thickness of skin, microvasculature, and adnexal structures. Confocalmicroscopy and histology demonstrated an intact and viable chondrocyte population surrounding irradiated sites. Conclusions: LCR with CO2 spray cooling can produce clinically significant shape change in the rabbit auricle while minimizing thermal cutaneous and cartilaginous injury and frostbite. This pilot study lends support for the potential use of CO2 spray as an adjunct to existing thermal-based cartilage reshaping modalities. An in vivo systematic evaluation of optimal laser dosimetry and cooling parameters is required. Lasers Surg. Med. 46:791–795, 2014. 2014 Wiley Periodicals, Inc.