Head injury and hemorrhagic shock: studies of the blood brain barrier and intracranial pressure after resuscitation with normal saline solution, 3% saline solution, and dextran-40

Abstract

The effect of fluid resuscitation from hemorrhagic shock on cerebral edema, intracranial pressure (ICP), and blood brain barrier function was investigated in the presence of a simulated head injury. Beagle dogs were anesthetized and ICP was measured via a right subarachnoid bolt while a contralateral epidural balloon was inflated in the left hemicranium to mimic a closed head injury. Forty percent of the dogs' blood was shed and the shock state was maintained for 1 hour. Resuscitation was initiated with shed blood and a volume of either normal saline solution (NS, n = 5), 10% dextran-40 (D-40, n = 6), or hypertonic (3%) saline solution (HS, n = 6) equal to the amount of shed blood. Evans blue solution was infused intravenously, and intravascular volume was then maintained with normal saline solution. Control (n = 5) dogs did not undergo shock, but received equivalent volumes of normal saline solution and Evans blue solution. The dogs were killed after 2 hours of resuscitation, and the brains were removed, weighed, and fixed in formalin. The average intracranial pressure value after epidural balloon inflation was 18.6 +/- 0.80 mm Hg and decreased equally in all groups during the shock period, averaging 10.8 +/- 1.24 mm Hg at the end of the shock period. Fluid resuscitation markedly elevated ICP in the NS and D-40 groups, reaching maximal values of 46.6 +/- 12.11 mm Hg and 45.3 +/- 28.95 mm Hg, respectively. Maximal ICP values in control and HS groups measured 21.8 +/- 1.36 mm Hg and 15.8 +/- 2.04 mm Hg, respectively (p less than 0.25 for HS versus NS control). Wet brain weights were significantly less in the HS group compared with either NS or D-40 groups (p less than 0.05). Coronal sections of fixed HS brains showed deep cortical Evans blue staining on the side of balloon injury. Therefore, in the presence of an intracranial mass lesion, resuscitation with hypertonic (3%) saline solution is accompanied by lower ICP values and less cerebral edema than is isotonic saline or colloid resuscitation. Blood brain barrier function is not restored by hypertonic saline solution resuscitation.