Intracranial pressure following resuscitation with albumin or saline in a cat model of meningitis*

Abstract

To compare the intracranial pressure after resuscitation to normovolemia by using 20% albumin or normal saline in a cat model of meningitis. Prospective, randomized animal study. University hospital laboratory. Twenty adult, male cats. Meningitis was induced by intrathecal injection of Escherichia coli-derived lipopolysaccharide (0.8 × 10 units/kg). Four hours after the lipopolysaccharide injection, the animals were randomized to intravenous treatment with 0.4 mL/kg/hr of 20% albumin or 7.5 mL/kg/hr of 0.9% sodium chloride for 6 hrs (n = 7 per group). A control group receiving lipopolysaccharide but no fluid was also studied (n = 6). Effects on intracranial pressure, mean arterial pressure, plasma volume (I-albumin technique), plasma oncotic pressure, and brain metabolism via cerebral interstitial lactate/pyruvate ratio and glycerol and glucose levels (microdialysis technique) were evaluated. Plasma volume decreased by approximately 20% and intracranial pressure increased from 10 to approximately 20 mm Hg at 4 hrs after the lipopolysaccharide injection. Six hours later, plasma volume had returned to baseline in both fluid groups while there was a further reduction in the control group. Intracranial pressure was higher in the saline group than in the albumin and control groups and was 25.8 ± 2.8 mm Hg, 18.3 ± 0.6 mm Hg, and 20.4 ± 1.7 mm Hg, respectively. Plasma oncotic pressure was higher in the albumin group than in the saline and control groups. Mean arterial pressure and microdialysis data were within normal range and did not differ among the groups. The results showed that the choice of resuscitation fluid may influence intracranial pressure in meningitis. The lower intracranial pressure in the colloid group may be explained by a higher plasma oncotic pressure and less fluid distribution to the brain interstitium.