Brain temperature exceeds systemic temperature in head-injured patients

Objective To identify the temperature differences in readings taken from the brain, jugular bulb, and core body in head-injured patients. Design Prospective, observational study. Setting Neurosurgical intensive care unit of a university-affiliated county hospital. Patients Thirty patients with severe head injuries had measurements of brain and core body temperatures. Fourteen patients also had measurements of jugular venous blood at the level of the jugular bulb. Interventions None. Measurements and main results Brain temperature was increased an average of 2.0 degrees F (1.1 degrees C) over the core body temperature. In individual patients, the average brain temperature increase over the core body temperature ranged from -0.5 degrees to 3.8 degrees F (-0.30 degrees to 2.1 degrees C). Jugular vein and core body temperatures were similar. The difference in the brain and body temperatures increased when cerebral perfusion pressure decreased to between 20 and 50 mm Hg. The difference in the brain and body temperatures decreased in those patients treated with barbiturate coma. Conclusions Direct measurement of temperature in head-injured patients is a safe procedure. Temperatures in the brain are typically increased over the core body temperature and the jugular bulb temperatures. Jugular vein temperature measurement is not a good measurement of brain temperature since it reflects body, not brain temperature. These findings support the potential importance of monitoring brain temperature and the importance of controlling fever in severely head-injured patients since brain temperature may be higher than expected.