Abstract
Improved tissue survival after frostbite injury has been demonstrated with immediate postinjury use of a thromboxane inhibitor. However, most patients with frostbite injury present to the hospital hours after their injury and the efficacy of thromboxane inhibition at that time is unknown. The current study evaluated the efficacy of a thromboxane inhibitor on frostbite tissue survival when initiated at the time of injury compared to 4 h postinjury. In a prospective study, three groups of nine rabbits received a standardized frostbite injury using a modified Weatherley–White model. A control group received no pharmacologic therapy; the other two groups were treated with 1 mg kg−1 methimazole initiated orally immediately or 4 h postinjury, respectively. Treatment was given every 8 h for a total of 96 h. Healing was followed until a clear line of demarcation was apparent (10 days). The percentage of viable ear surface area remaining at the end of the study was measured and used to compare the effectiveness of treatments. Analysis of variance was used to determine statistical significance. No significant difference (p = .388) was observed among the frostbite injury of the control group and either treatment group. Thirty percent of animals did not reach the study end point secondary to an outbreak of Escherichia coli diarrhea, reducing the study power to a 33% ability to detect a 35% difference in tissue survival. Despite the reduced power, this study questions the efficacy of thromboxane inhibition in improving frostbite tissue survival, whether therapy is initiated immediately or is delayed. These data suggest that further investigation is warranted to determine the role of thromboxane inhibition in frostbite injury.