Cerebral blood flow and rheologic alterations by hyperosmolar therapy in patients with brain oedema

Cerebral blood flow was assessed as initial slope index by 133-Xenon inhalation in 36 patients with brain tumours subjected to osmotic dehydration. The following solutions were employed: I. 20% mannitol, II. 40% sorbitol, III. 10% glycerol. Parameters affecting blood rheologic properties as Hct, plasma viscosity, red blood cell aggregation and fluidity were simultaneously studied. CBF which was reduced in the oedematous hemisphere with brain tumour increased during infusion and thereafter by mannitol or sorbitol, respectively. The blood flow response to glycerol was more delayed, less intense, but maintained longer. Hct and plasma viscosity were significantly reduced by all osmotic agents, while red blood cell fluidity fell and aggregation rose under mannitol. It is concluded that sorbitol (40%) is superior for emergency treatment with high ICP, whereas glycerol seems to be preferable to improve cerebral blood flow in oedematous brain.