MP06: Predictors of hypothermia upon emergency department arrival in severe trauma patients transported to hospital via emergency medical services

Abstract

Introduction: Hypothermia in severe trauma patients can increase mortality by 25%. Active re-warming decreases mortality and is recommended in trauma management guidelines. Despite this, many emergency medical services (EMS) vehicles do not carry equipment for active re-warming. This study sought to determine the local rate of hypothermia in major trauma patients on trauma centre arrival (TCA), and to establish which patients are at highest risk by identifying factors present in the pre-hospital setting associated with hypothermia in a humid continental climate. Methods: This single-centre retrospective chart review included adults (age 18) in the local trauma registry (trauma team activation or injury severity score >12) from January 2009-June 2016. Patients were excluded if: temperature on TCA unknown or 38°C, not transported by EMS, or if there was >24 hrs from injury to TCA. The primary outcome was the rate of hypothermia (<35°C) in major trauma patients transported by EMS on arrival at the local trauma centre. Secondary outcomes included hospital length of stay and survival to discharge. Logistic regression was used to identify predictors of hypothermia on TCA; it included the following factors: age, sex, weight, number of comorbidities, injury severity, injury mechanism, EMS modality, direct transport from scene or referred from peripheral hospital, time on scene, transport time, local temperature, and pre-hospital heart rate, systolic blood pressure (SBP), intubation, and volume of crystalloid. Results: A total of 3070 adult traumas were included, 159 of which were hypothermic on TCA a rate of 5%. Multivariate analysis identified seven risk factors for hypothermia: intubation pre-hospital (OR 8.10, p<0.001), blunt trauma (OR 3.37, p=0.044 vs. penetrating, and OR 7.35, p=0.023 vs. other), direct transport (OR 1.94, p=0.005), number of comorbidities (OR 1.14, p=0.036), injury severity (OR 1.03, p<0.001), 1°C local temperature drop (OR 1.03, p<0.001), and 1mmHg SBP drop (OR 1.01, p<0.001). Ninety-four percent of normothermic patients and 69.2% of hypothermic patients survived to discharge. Average length of stay was 7.98 and 15.23 days respectively. Conclusion: Avoidance of hypothermia is imperative to the management of major trauma patients. Those at highest risk in a humid continental climate are severely injured blunt trauma patients with multiple co-morbidities, a low pre-hospital SBP and EMS intubation. Future studies should focus on the benefits of pre-hospital rewarming in these high-risk patients.