Cerebral Carbohydrate Metabolism During Hypocarbia in Man Studies During Nitrous Oxide Anesthesia

Abstract

Brain carbohydrate metabolism was studied in 11 healthy male volunteers during anesthesia induced with intravenous thiopental (5 mg/kg) and maintained with 70% N2O-30% O2 and d-tubocurarine. When arterial PCO2 (PaCO2) was normal, oxygen and glucose consumption were reduced approximately 25% from the normal value in conscious man; but no change in the pattern of glucose utilization was noted. A reduction in PaCO2 below 20 mm of Hg was accompanied by a decreased aerobic and an increased anaerobic utilization of glucose. Mild, readily reversible changes in the electroencephalogrom (EEG) pattern also occurred when PaCO2 was less than 20 mm of Hg. Clinical implications of these changes are discussed. The validity of several indices of cerebral carbohydrate metabolism is considered.