Field Study on Intravenous Iloprost for Treatment of Severe Frostbite at High Altitude

The goal of this observational study is to learn whether intravenous iloprost treatment for severe frostbite (grades 3-4) is feasible and safe when delivered in pre-hospital, remote high-altitude settings. The main questions it aims to answer are: * Is it feasible to initiate and deliver guideline-based intravenous iloprost for grade 3-4 frostbite at high altitude and what logistical barriers arise? * Does field-based initiation of iloprost increase tissue preservation and reduce amputations (compared to historical cases from similar settings)? Participants receiving Iloprost as part of a frostbite treatment will be followed up after discharge as well as 6, 12 and 18 months to assess tissue preservation and long-term sequelae from the initial frostbite injury.