The effect of hypertonic fluid resuscitation on brain edema in rabbits subjected to brain injury and hemorrhagic shock.

Small-volume resuscitation with 7.2% NaCl/10% dextran 60 (HHS) restores cardiovascular stability faster than all other therapeutic modalities currently known. This study was undertaken to elucidate the effects of HHS on the brain, specifically on the formation of posttraumatic brain edema. HHS was administered to anesthetized albino rabbits with or without a focal cryogenic brain lesion and hemorrhagic shock. Specific gravity of small tissue samples was determined 4 h after injury and values were topographically assembled to form a color-coded map of both hemispheres, allowing for a high resolution mapping of brain edema. Cerebral blood flow on the side of the lesion, as assessed by the H2 clearance method, increased transiently after injury but remained unchanged from baseline during shock and after infusion of HHS, indicating intact cerebrovascular autoregulation. The cryogenic lesion without subsequent HHS infusion resulted in significant brain edema formation in grey and white matter of the exposed hemisphere. In injured animals, resuscitation with HHS led to a global reduction of brain water content in both hemispheres. We conclude that small-volume resuscitation with HHS does not worsen posttraumatic brain edema. To the contrary, our results show that it decreases cerebral water content even in regions close to the injury. This makes it worthwhile to investigate the benefits of HHS for the treatment of intracranial hypertension.