206 ALTERATION OF BRAIN VOLUME-PRESSURE RESPONSE DURING OCTANOATE INFUSION IN RABBITS

Abstract

Elevated serum concentrations of short chain fatty acids, including octanoate, are found in patients with Reye's Syndrome. Continuous intravenous infusion of octanoate in rabbits has been reported to result in similar clinical and chemical changes of Reye's Syndrome including hyperventilation, coma, seizures, increased intracranial pressure and hyperammonemia. To further evaluate the effect of octanoate on brain compliance we evaluated the brain volume-pressure response (VPR) during continuous octanoate infusion in rabbits. Volumes of 0.1ml were infused into the cisternal space of control rabbits (C) infused with normal saline and rabbits with continuous octanoate infusions at 1.5mmoles/hr (O). VPR was 1mmHg (C) vs 4mmHg (O). Time to recovery of initial intracranial pressure was 10 seconds (O). Both groups received pavulon 1mg/hr and were mechanically ventilated without changes in pH, pCO2 or pO2. Intracranial pressure (ICP) ranged 5-10mmHg and no differences were noted between (C) or (O) rabbits (p=ns). We conclude that continuous intravenous infusions of octanoate in rabbits 1) alter the brain VPR, and 2) do not produce elevations in ICP at 1.5mmoles/hr.