4 The Effects of Rapid Rewarming on Tissue Salvage in Severe Frostbite Injury

Abstract

Abstract Introduction Frostbite is a high morbidity, high cost injury caused by soft tissue freezing, which can lead to digit or limb necrosis requiring amputation. Many severe frostbite injuries are initially assessed at healthcare facilities outside of dedicated burn centers. Rapid rewarming is the widely accepted first line treatment and is typically performed by placing the affected body parts in a 40–42 C water bath for 15–30 minutes. The aim of this study is to ascertain the clinical practices at the referring facilities before transferring patients with severe frostbite to regional burn centers, as well as any impact on clinical outcomes. Methods Upon IRB approval, retrospective chart review identified severe frostbite patients admitted to our ABA verified burn center between 2014 and 2019. Records were reviewed to identify initial rewarming strategy from referring facilities. Time to thrombolytics after initial admission was also noted. Amputation and salvage rates were calculated. Results Seventy-four severe frostbite patients presented to outside facilities and 96 were direct admissions (N=170). There was no significant difference in age, gender, social and comorbid characteristics between transfer and direct admit groups. We found that a significantly greater number of transfer patients received tPA versus direct admit patients (82.4% v 66.7%, P=0.023). On average, tPA was given 1.5 hours earlier in the direct admit patients (5.8 vs 7.3 hours, P=0.004). There was no significant difference in tissue at risk scores (10.2 v 9.1, P=0.465), percentage of patients requiring amputation (35.1% v 24.0%, P=0.126), or tissue salvage rates (76.8 v 84.2, P=0.207) between the two groups. In the cohort of patients presenting to outside hospitals, 66% received rapid rewarming. Other warming modalities at referring centers included warm intravenous fluids, heated blankets, heated oxygen, catheter-based warming, bladder irrigation, and heat packs. On regression analysis, the use of rapid rewarming was not a significant predictor for poor outcomes for limb salvage (P=0.578). The early use of thrombolytics had a positive outcome on limb salvage (P=0.013). Conclusions Initial rewarming practices for frostbite vary dramatically at outside centers. While rapid rewarming was not statistically associated with improved outcomes, variations in specific treatment modalities and limited sample size decrease the likelihood of identifying differences in a retrospective study. Outreach efforts are needed to educate outside centers about the importance of rapid rewarming and early transfer of severe frostbite patients to burn centers for thrombolytic therapy. Applicability of Research to Practice This study shows the need for outreach and education of frostbite management for non-burn centers.