Course of cerebral blood flow and metabolism following severe brain injury. Correlation with neurological function and outcome

This study was carried out investigate the course of cerebral blood flow and metabolism in fifty five head-injured patients and to specifically characterize the changes in oxidative and glucose indices in the acute post-traumatic period with regard to neurological condition and functional outcome. Blood flow volume (BFV) measurements were obtained from the extracranial internal carotid artery using a dual-beam angle-independent digital Doppler ultrasound. Cerebral metabolism was studied using blood sample, blood gas, blood saturation, hemoglobin, hematocrit, pH and glucose plasma concentrations. Arterial jugular differences were then calculated and used to determine global cerebral metabolic rates of oxygen (gCMRO2) and glucose (gCMRGlc). In patients with good outcome, CBF remained stable within the normal range whereas in patients with poor outcome, the course of CBF was characterized by a triphasic pattern defined by a secondary decrease on the third day. CMRO2 showed a significant and progressive correlation with level of consciousness expressed by means of GCS. Lower CBF values were significantly associated with poorer outcome.