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 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 non-responders enables 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% partial responders, and 5.3% non-responders for surgical outcome. The median time to thrombolytics was 5.5 hours (range 1-14.5) for full responder; 7 hours (range 3.5-14) for partial responder; and 10 hours (range 1.5-11.5) for non-responders. Full responders exhibited smaller initial perfusion deficits. Psychosocial or comorbid factors were not significantly different across groups. Non-response was associated with 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% partial responders, and 15% non-responders. Full responders for imaging outcome corresponded with surgical outcomes and had no amputations, while 37.7% of partial responders and 42.9% of non-responders on imaging outcome had amputations. This study is the largest to evaluate thrombolytic outcomes in severe frostbite injured patients, proving new insight into thrombolytics 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 thrombolytics treatment windows.