Hypothermia Following Head Injury

Pathophysiological Mechanisms

Severe head injury can directly disrupt temperature regulation in the brain, leaving patients vulnerable to heat loss 1, 2
Traumatic brain injury (TBI) with low Glasgow Coma Score (GCS of 3) is associated with higher risk of hypothermia development 2, 3
The presence of hypothermia in severe injury is both instrumental and ancillary in the physiologic deterioration following trauma 1

Severity of injury is strongly correlated with hypothermia risk - higher Injury Severity Score (ISS) increases odds of hypothermia (OR 1.04) 1, 2
Prehospital intubation significantly increases hypothermia risk (OR 5.18) 1
Hypotension (systolic blood pressure <100 mmHg) triples the risk of hypothermia (OR 3.04) 1
Blood loss and large open wounds commonly associated with severe trauma compound the risk 1

Each 1°C drop in temperature is associated with approximately 10% drop in coagulation factor function 4, 5
Hypothermia alters platelet function, impairs enzyme activity, and increases fibrinolysis 4, 6
Body temperatures below 34°C significantly compromise blood coagulation 4, 5
The combination of hypothermia with acidosis creates a synergistic negative effect on coagulation that is more severe than either condition alone 1

Hypothermia (defined as core body temperature <35°C) is an ominous clinical sign associated with high mortality and blood loss in trauma patients 4, 5
Hypothermic trauma patients require more blood products and have higher morbidity and mortality rates 4, 6
In patients with TBI, hypothermia represents an independent risk factor for bleeding and death 4, 5

Brain temperature can be up to 2°C higher than systemic temperature and may vary independently based on pathology 7
Temperature monitoring should use core measurements (bladder, esophageal, cerebral) rather than superficial measurements (skin, tympanic) in severe TBI 8, 9
Neurogenic fever (temperature >37.5°C) is common in TBI and should be promptly treated to prevent secondary brain injury 8, 10

While uncontrolled hypothermia is detrimental, controlled therapeutic hypothermia may be beneficial in specific TBI scenarios 8, 10
Mild hypothermia (target core temperature 35.0-36.0°C) may be considered for intracranial pressure control when tier 1 and 2 treatments have failed 8, 10
Automated feedback-controlled temperature management devices are recommended for precise temperature control in TBI patients 8, 7

Steps to prevent hypothermia include removing wet clothing, covering the patient, increasing ambient temperature, forced air warming, and warm fluid therapy 4, 5
Cold infusion fluids (typically below 21°C) significantly contribute to hypothermia risk in trauma patients 1, 2
Warming infusion fluids can dramatically reduce hypothermia-associated complications, including cardiac arrest 1
In extreme cases, extracorporeal re-warming devices may be necessary 4, 5