Abnormal Hemispheric Blood Flow and Metabolism in Cerebrovascular Disease. II. Therapeutic Trials With 5% CO2 Inhalation, Hyperventilation and Intravenous Infusion of THAM Mannitol

The effects of inhalation of 5% CO2 in air, active hyperventilation, and intravenous infusion of THAM and mannitol on hemispheric blood flow (HBF) and metabolism were investigated in the ischemic hemispheres of patients with acute and chronic cerebral ischemia and in one with brain tumor. Five percent CO2 inhalation increased HBF and decreased hemispheric RQ (HRQ) in the ischemic hemisphere. Hyperventilation decreased HBF and increased hemispheric glucose consumption. THAM infusion had no effect on HBF and metabolism, and mannitol increased HBF but had no effect on metabolism in the ischemic hemispheres. In the patient with brain tumor, 5% CO2 inhalation caused an "intracerebral steal" probably as a result of increasing intracranial pressure and "squeezing" or displacing of blood from the hemisphere swollen by tumor into the normal hemisphere. Intravenous injection of mannitol increased the blood flow to the hemisphere containing the tumor by temporarily reducing intracranial pressure.