BRAIN EDEMA AND NEUROLOGIC STATUS WITH RAPID INFUSION OF 0.9-PERCENT SALINE OR 5-PERCENT DEXTROSE AFTER HEAD TRAUMA

We previously reported that intravenous (i.v.) administration of large volumes (0.2 ml/g) of either an isotonic dextrose-free solution or 5% dextrose solution given over 18 h after closed head trauma (CHT) in r ats did not significantly affect neurological severity score or brain tissue specific gravity. However, it is possible that with more rapid administration, isotonic or 5% dextrose i.v. solutions may alter neuro logical outcome after CHT. Our study examined whether neurological sev erity score, brain tissue specific gravity and water content, and bloo d composition were significantly altered when 0.25 ml/g of either 0.9% saline or 5% dextrose was given i.v. over 0.5 h (rather than over 18 h) after CHT. Eighty-four rats that survived ether anesthesia and CHT were randomly assigned to one of 11 experimental groups. Saline- and d extrose-treated rats were evaluated at 4 and 48 h after CHT and were c ompared to rats without CHT and to untreated rats at 4 and 48 h after CHT. There were no statistically significant differences in neurologic outcome and brain edema between the untreated and the saline-treated groups. However, 5% dextrose i.v. increased mortality (group 6 and 11, 50 and 0% survivors, respectively), decreased specific gravity in the noncontused hemisphere, and worsened neurologic outcome with and with out CHT. Blood osmolality remained stable in comparison to the baselin e value of 291.9 +/- 7.4 mOsm/kg (mean +/- SD). Sodium and glucose lev els, initially 139.2 +/- 2.6 mEq/L and 168 +/- 61.9 g%, remained stabl e in the saline-treated animals at 138 +/- 2.1 mEq/L and 162.7 +/- 18. 5 g%, but after 5% dextrose i.v. administration, values decreased to 8 6.3 +/- 9.7 mEq/L and increased to >450 mg/dl, respectively. We conclu de that in our model of CHT, giving large boluses of 0.9% saline i.v. does not affect electrolyte balance, neurologic outcome, or formation of brain edema in rats with or without CHT. However, the same volume o f 5% dextrose i.v. decreased serum sodium, increased brain edema in th e noncontused hemisphere (in rats with CHT) and in intact brains (in r ats without CHT), and decreased neurological outcome with and without CHT.