Three Forward Aeromedical Evacuation platforms operate in Southern Afghanistan: UK Medical Emergency Response Team (MERT), US Air Force Expeditionary Rescue Squadron (PEDRO), and US Army Medical Evacuation Squadrons (DUSTOFF), each with a different clinical capability. Recent evidence suggests that retrieval by a platform with a greater clinical capability (MERT) is associated with improved mortality in critical patients when compared with platforms with less clinical capability (PEDRO and DUSTOFF). It is unclear whether this is due to en route resuscitation or the dispatch procedure. The aim of this study was to compare prehospital Shock Index (SI = heart rate / systolic blood pressure) with admission values as a measure of resuscitation, across these platforms. Patients were identified from the Department of Defense Trauma Registry, who were evacuated between June 2009 and June 2011 in Southern Afghanistan. Data on platform type, physiology, and injury severity was extracted. Overall, 865 patients were identified: 478 MERT, 291 PEDRO, and 96 DUSTOFF patients and groups were compared across three injury severity scoring (ISS) bins: 1 to 9, 10 to 25, and 26 or greater. An improvement in the admission SI was observed across all platforms in the lowest ISS bin. Within the middle bin, both the MERT and PEDRO groups saw improved SI on admission, but not the DUSTOFF group. This trend was continued only in the MERT group for the highest ISS bin (1.39 ± 0.62 vs. 1.09 ± 0.42; P = 0.001), whereas a deterioration was identified in the PEDRO group (0.88 ± 0.37 vs. 1.02 ± 0.43; P = 0.440). The use of a Forward Aeromedical Evacuation platform with a greater clinical capability is associated with an improved hemodynamic status in critical casualties. The ideal prehospital triage should endeavor to match patient need with clinical capability.