title: In vivo laser cartilage reshaping with carbon dioxide spray cooling in a rabbit ear model: a pilot study.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  The midportion of live rabbit ears were irradiated with a 1.45 µm wavelength diode laser (12 J/cm(2)) with simultaneous CO2 spray cooling (85 millisecond 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 the flexed position for 30 days following exposure. A total of 5 ears each were allocated to the experimental and control groups.
  
  
  RESULTS
  Shape change was observed in all irradiated ears (mean 70 ± 3°), which was statistically different from control (mean 37 ± 11°, P = 0.009). No significant thermal cutaneous injury was observed, with preservation of the full thickness of skin, microvasculature, and adnexal structures. Confocal microscopy 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.
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California - Irvine, 1002 Health Sciences Rd, Irvine, California, 92612.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Kuan
authors.forename: Ashley A
authors.initials: AA
authors.lastname: Hamamoto
authors.forename: Victor
authors.initials: V
authors.lastname: Sun
authors.forename: Tony
authors.initials: T
authors.lastname: Nguyen
authors.forename: Cyrus T
authors.initials: CT
authors.lastname: Manuel
authors.forename: Dmitry E
authors.initials: DE
authors.lastname: Protsenko
authors.forename: Brian J F
authors.initials: BJ
authors.lastname: Wong
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Nelson
authors.forename: Wangcun
authors.initials: W
authors.lastname: Jia
mesh_terms: D000818:Animals; D002056:Burns / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D002245:Carbon Dioxide / Q000627:therapeutic use*; D017679:Cryotherapy / Q000379:methods*; D004425:Ear Cartilage / Q000601:surgery*; D053685:Laser Therapy / Q000009:adverse effects*; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D023421:Models, Animal; D010865:Pilot Projects; D011817:Rabbits; D012867:Skin / Q000473:pathology / Q000528:radiation effects
chemical_list: D002245:Carbon Dioxide
keywords: facial plastic surgery; laser; macrotia; otolaryngology