Evaluation of cerebrovascular CO2-reactivity and autoregulation in patients with post-traumatic diffuse brain swelling (diffuse injury III).
The present study was undertaken to elucidate the status of autoregulation and CO2-reactivity soon after injury in patients with a post-traumatic diffuse bilateral brain swelling. A prospective study was carried out in 31 consecutively admitted patients with a severe head injury and a Diffuse Brain Injury type III, following the definition stated by the Traumatic Coma Data Bank classification. To evaluate CO2-reactivity, AVDO2 was measured before and after ventilator manipulations. Assuming a constant CMRO2 during the test, changes in 1/AVDO2 reflect changes in CBF. Patients with changes in estimated CBF below or equal to 1% were included in the impaired/abolished CO2-reactivity group. To test autoregulation, hypertension was induced using phenylephrine. Arterial and jugular blood samples were taken to calculate AVDO2 before and after a steady state of MABP was obtained. Cerebrovascular response to CO2 was globally preserved in all but two cases (6.5%). In contrast, autoregulation was globally preserved in 10 (32.3%) and impaired/abolished in 21 cases (67.7%). Our data do not support the premise that increasing cerebral perfusion pressure by inducing arterial hypertension is beneficial in those patients with a diffuse brain swelling in whom autoregulation is impaired or abolished. Clinical implications for treatment are discussed.
Department of Neurosurgery, Vall d'Hebron University Hospitals, Barcelona, Spain.
J
J
Sahuquillo
F
F
Munar
M
M
Baguena
M A
MA
Poca
S
S
Pedraza
A
A
Rodríguez-Baeza
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D001929:Brain Edema / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000502:physiology*; D005260:Female; D016489:Head Injuries, Closed / Q000503:physiopathology*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014666:Vasomotor System / Q000503:physiopathology
D002245:Carbon Dioxide