Time to Thrombolytics and Tissue Salvage: Assessing Response Following Severe Frostbite Injury.

Approximately 30% of severe frostbite injuries result in amputation. Thrombolytic therapy is used to reduce tissue loss following severe frostbite injury. This study evaluates factors impacting the effectiveness of thrombolytics using post-treatment perfusion imaging and amputation level as outcome measures. We hypothesize that categorizing thrombolytic-treated patients into full, partial, and nonresponders enable a nuanced evaluation of treatment effectiveness. A prospectively maintained frostbite database was reviewed for patients with post-rewarming perfusion deficits measured by Tc99 scans who received IV thrombolytics. Of 131 patients, 71% were full responders, 23.7% were partial responders, and 5.3% were nonresponders for surgical outcome. The median time to thrombolytics was 5.5 h (range 1-14.5) for full responders; 7 h (range 3.5-14) for partial responders; and 10 h (range 1.5-11.5) for nonresponders. Full responders exhibited smaller initial perfusion deficits. Psychosocial or comorbid factors were not significantly different across groups. Nonresponse was associated with a longer time to thrombolytics, larger perfusion deficits, and cellulitis/infection. Using imaging outcomes to reduce confounding by infection, 93 patients were evaluated: 28% were full responders, 57% were partial responders, and 15% were nonresponders. Full responders for imaging outcomes corresponded with surgical outcomes and had no amputations, while 37.7% of partial responders and 42.9% of nonresponders on imaging outcomes had amputations. This study is the largest to evaluate thrombolytic outcomes in severe frostbite-injured patients, showing nearly 95% of patients improve after thrombolytic treatment for severe frostbite injury. This provides new insight into thrombolytic responses and a novel assessment of thrombolytic treatment efficacy. These findings underscore the importance of timely thrombolytic administration and demonstrate benefits for patients treated outside the standard thrombolytic treatment windows.