Influence of dopamine on cerebral blood flow, and metabolism for oxygen and glucose under barbiturate administration in cats

Abstract

The effect of dopamine during barbiturate therapy was investigated in 29 cats including 5 sham-operated cats. According to Kiersey's classification of electro-encephalographic patterns, physiological variables, cerebral metabolic rates for oxygen and glucose, cerebral blood flow (CBF), and intracranial pressure (ICP), etc. were evaluated in each electro-encephalographic pattern. Oxygen-glucose index was calculated and used as an indicator for aerobic or anaerobic metabolism of glucose. Group 1 (12 cats), to which only thiamylal was administered, maintained aerobic glycolysis due to a parallel reduction of cerebral metabolic rates for oxygen and glucose (about half of the initial value at Kiersey's fifth pattern) in spite of reduction of CBF and mean arterial blood pressure (MABP). Group 2 (12 cats), to which dopamine was administered in addition to thiamylal due to a reduction of MABP, showed anaerobic glycolysis though MABP and CBF were maintained. These findings are ascribed to an increase of cerebral metabolic rate for glucose up to 130% of the initial value though cerebral metabolic rate for oxygen decreased down to half of the initial value: The beneficial effect of barbiturate on cerebral metabolism was reduced by use of dopamine. ICP was reduced in both groups. Our result indicates that administration of extracellular fluid may be preferable for treatment of hypotension during barbiturate therapy than dopamine medication.