The importance of protein content in the oedema fluid for the resolution of brain oedema.

The infusion model of oedema is developed in the rat. Unilateral, constant volume, intracerebral infusions of oedema fluid of varying protein (bovine albumin) concentrations are performed. Brain tissue is analyzed for water content using the gravimetric technique. The authors find significant differences in the spatial distribution of brain water in the different infusion groups at 48 and 72 hours post infusion. The control infusate (mock cerebrospinal fluid) clears by 72 hours. However, infusates containing protein (32.5 and 65.0 mg/ml albumin) are not completely cleared until 5 to 8 days post infusion, with the less concentrated solution clearing more rapidly in the area of infusion at 72 and 96 hours post infusion. The data support the hypothesis that the rate of clearance of vasogenic brain oedema is dependent on the amount of extravasated protein.