Pre-hospital Tourniquet in Extremity Injury

2.1. Objective: • Primary Objective: To compare outcomes of patients with extremity injuries presenting with or without pre-hospital tourniquet placement. 2.2. Study Outcome Measures * Primary Outcome: Incidence of arrival in shock (SBP \<90) * Secondary Outcomes: Demographics, comorbidities, mechanism of injury, cause of injury, diagnosis codes, procedure codes, Injury Severity Scale, Abbreviated Injury Scale, operative management vs. non-operative management, radiologic findings, pathologic findings, tourniquet effectiveness (as determined both subjectively by trauma surgeon and objectively by presence vs. absence of pulse below level of tourniquet application), total number of units of blood products transfused within first 24 hrs, total number of units of blood products for index admission, type of blood products or other fluid given, hospital length of stay, ICU length of stay, ventilator days, infectious complications, other complications, discharge disposition, 24 hr mortality, overall mortality.