Changes in cerebrovascular response during brain hypothermia after traumatic brain injury.
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.


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 SjO2, 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.


CONCLUSIONS
These data suggest cerebral vasoactivity could be altered at the rewarming stage. Hypothermia runs a risk of hyperemia at the rewarming stage, which induced a decrease in cerebral vasoresistance.
Kinoshita
K
K
Department of Critical Care and Emergency Medicine, Nihon University School of Medicine, Tokyo, Japan. kosaku@med.nihon-u.ac.jp
Hayashi
N
N
Sakurai
A
A
Utagawa
A
A
Moriya
T
T
D000208:Acute Disease; D001783:Blood Flow Velocity; D001929:Brain Edema / Q000000981:diagnostic imaging / Q000209:etiology; D001930:Brain Injuries / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D006801:Humans; D007036:Hypothermia, Induced; D007601:Jugular Veins; D020768:Middle Cerebral Artery / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D011673:Pulsatile Flow; D014057:Tomography, X-Ray Computed; D017585:Ultrasonography, Doppler, Transcranial
D010100:Oxygen