Changes in cerebrovascular response during brain hypothermia after traumatic brain injury

Abstract

Objective. Transcranial Doppler sonography (TCD) provides a rapid and noninvasive assessment of cerebral hemodynamics after traumatic brain injury. This study evaluates the change of cerebrovascular response at the rewarming stage of brain hypothermia using TCD. Material and methods. Seventeen patients who had suffered from closed brain injury were investigated with daily TCD recordings and the changes in flow velocities were evaluated to determine whether they reflected the temperature during brain hypothermia. All patients who had treated brain hypothermia underwent continuous monitoring of SjOi, mean arterial blood pressure, and intracranial pressure (ICP). Results. No significant changes in ICP and cerebral perfusion pressure (CPP) were recorded in all cases. Of 17 patients, 5 had a significant increase in SjO2 > 75% or more, retrospectively, with a robust increase in flow velocities of the middle cerebral artery (P < .01) at the rewarming stage. These cases marked a decrease in pulsatility index (P < .05) concomitant with an increase in SjO2 values. The CT scan revealed acute brain swelling in these cases. Conclusion. These data suggest cerebral vasoaetivity could be altered at the rewarming stage. Hypothermia runs a risk of hyperemia at the rewarming stage, which induced a decrease in cerebral vaso- resistance. © Springer-Verlag 2003.