Environmental Hyperthermia in Prehospital Patients with Major Traumatic Brain Injury.

Background: Traumatic brain injury (TBI) results in an estimated 1.7 million emergency department visits each year in the United States. These injuries frequently occur outside, leaving injured individuals exposed to environmental temperature extremes before they are transported to a hospital.

Objective: Evaluate the existing literature for evidence that exposure to high temperatures immediately after TBI could result in elevated body temperatures (EBTs), and whether or not EBTs affect patient outcomes.

Discussion: It has been clear since the early 1980s that after brain injury, exposure to environmental temperatures can cause hypothermia, and that this represents a significant contributor to increased morbidity and mortality. Less is known about elevated body temperature. Early evidence from the Iraq and Afghanistan wars indicated that exposure to elevated environmental temperatures in the prehospital setting may result in significant EBTs, however, it is unclear what impact these EBTs might have on outcomes in TBI patients. In the hospital, EBT, or neurogenic fever, is thought to be due to the acute-phase reaction that follows critical injury, and these high body temperatures are associated with poor outcomes after TBI.

Conclusion: Hospital data suggest that EBTs are associated with poor outcomes, and some preliminary reports suggest that early EBTs are common after TBI in the prehospital setting. However, it remains unclear whether patients with TBI have an increased risk of EBTs after exposure to high environmental temperatures, or if this very early "hyperthermia" might cause secondary injury after TBI.