Cerebral circulation and metabolism in septic encephalopathy have not been well documented. The authors measured cerebral blood flow (CBF) and metabolic rate for oxygen (CMRO2) in six patients with septic encephalopathy associated with multiple organ failure (three to five organs). They found that CBF and CMRO2 were significantly lower than awake control values of 46 +/- 2 to 28 +/- 3 mL/100g/min (mean +/- SEM) and 3.1 +/- 0.2 to 1.2 +/- 0.2 mL/100g/min, respectively. Cerebral vascular resistance (CVR) and cerebral circulatory index (CCI:CBF/CMRO2) were significantly higher than the control values of 2.0 +/- 0.1 to 3.0 +/- 0.4 mm Hg/mL/100g/min and 15.1 +/- 0.8 to 24.2 +/- 3.3, respectively. At the time of cerebral circulatory and metabolic measurements, their consciousness varied between 4 and 10 as evaluated by the Glasgow coma scale. The electroencephalogram showed diffuse slow wave activity and the latency of the auditory brain stem evoked response was prolonged in four of six patients. Computed brain tomography showed either no abnormality or mild atrophy. It is concluded that CBF and CMRO2 are disproportionally decreased during septic encephalopathy in association with dysfunction of the CNS and decreased electrical activity.