Effect of Rapid and Slow Infusions of the Mannitol on Regional Cerebral Blood Flow and Brain Edema in Focal Brain Compression of Cats

ABSTRACT

The aim of the present study has been to examine the effect of mannitol on regional cerebral blood flow(rCBF) and brain edema both at normal and increased intracranial pressure and to determine which of two infusion methods, rapid infusion or slow infusion of mannitol, has better effect on brain compression. Thirty five adult cats weighting between 2.7 and 4.2 kg were used in this study. The animals were divided into four groups Mannitol administered normal control(n=5), brain compression(n=10), rapid mannitol treated-brain compression(n=10) and slow mannitol treated-brain compression groups(n=10) respectively. A small balloon connected to a fine polyethylene tube was placed in the epidural space of the right frontal region through a small burr hole and inflated with on ml of distilled water in increment of 0.2 ml to simulate the expanding mass. The measurements of rCBF and electroencephalography(EEG) activity were carried out in each animal. Mannitol was given in bolus of 1g/kg body weight via the femoral vein and two methods of mannitol infusion were used as rapid infusion which was infused the mannitol within 3 min and slow infusion, infused within 15min. The rCBF was measured by hydrogen clearance method and the brain edema was measured by gravimetric technique. In brain compression group, the ICP rose immediately following brain compression to 133.00+/-9.49 mmH2O from 78.00+/-11.35 mmH2O and maintained the elevation during the experiment. Treatment with mannitol in brain compression animals, decreased the ICP at 5 min after infusion of mannitol, and the decreased ICP was maintained for one hour. Brain compression animals showed a significant reduction of rCBF by 38% and 46% in right parietal lobe at the 60 min and 120 min after brain compression, respectively. In mannitol treated brain compression animals, the administration of mannitol made the reduced rCBF increase to baseline value at 30 min after treatment and the increased rCBF value was maintained for one hour. There was generalized brain edema, as judged by a decreased specific gravity in the brain compression, which was maximal close to the brain compression site. The severity of the brain edema was less in the mannitol treated brain compression group than in brain compression group. This study demonstrated that there was no significant different effects between rapid and slow infusion of mannitol in brain compression.