The predictive value of cerebral anaerobic metabolism with cerebral infarction after head injury

Cerebral ischemia is a common mechanism of secondary brain injury following severe head injury. The cerebral metabolic rate of oxygen (CMRO₂) and of lactate (CMRL), as well as cerebral blood flow (CBF) were measured daily for 5 days after head injury in 44 comatose head-injured patients to determine if metabolic changes could identify the patients who would develop cerebral infarction. Of 41 patients whose CBF remained at levels regarded as adequate to prevent infarction (CBF ≥ 0.2 ml/gm/min), the six who showed a cerebral infarction on computerized tomography (CT) scans exhibited characteristic cerebral metabolic patterns: a CMRO₂ of less than 0.6 μmol/gm/min on one or more of the days monitored, and markedly elevated cerebral lactate production (CMRL<-0.06μmol/gm/min) on Days 1 and/or 2 after injury. Patients who had no areas of infarction on serial CT scans typically had a CMRO₂ of 0.6 μmol/gm/min or higher and a low cerebral lactate production. Measurement of CMRO₂ and CMRL can be obtained at the bedside and can indicate the presence of an evolving ischemic infarct after head injury.