The effect of hypertonic resuscitation on pial arteriolar tone after brain injury and shock

Traumatic brain injury: a review of pathophysiology and management

“…Hypertonic saline administration also improves regional CBF via dehydration of cerebrovascular endothelial cells. Reduction of endothelial edema causes a relative increase in vessel diameter improving CBF leading to a reduction in ICP and enhanced cerebral oxygen delivery 78 . Hypertonic saline solutions have also been shown to decrease brain excitotoxicity by promoting reuptake of excitatory amino acids, such as glutamate, into the intracellular space, 79 and by reducing adhesion of polymorphonuclear cells to microvasculature modulating the inflammatory response 80 .…”

“…Hypertonic saline solutions have also been shown to decrease brain excitotoxicity by promoting reuptake of excitatory amino acids, such as glutamate, into the intracellular space, 79 and by reducing adhesion of polymorphonuclear cells to microvasculature modulating the inflammatory response 80 . The recommended dose of hypertonic saline is controversial, with studies looking at varying strengths and administration protocols 48,51,52,78–85 . Currently recommended doses include 4 mL/kg of 7.5% sodium chloride 51 or 5.3 mL/kg of 3% sodium chloride 52 administered over 2–5 minutes.…”

Delayed Fluid Resuscitation of Head Injury and Uncontrolled Hemorrhagic Shock

“…Shock followed by fluid resuscitation with RL leads to endothelial cell swelling, 19 capillary plugging with polymorphonuclear leukocytes, 19,20 and a decrease in pial arteriolar diameter. 21 Endothelial cell swelling and capillary plugging can occur following shock alone, but our results suggest that resuscitation with RL may exacerbate these processes. Interestingly, Mazzoni et al 19 have shown that luminal narrowing and decreased red blood cell flux, caused by swelling of skeletal muscle endothelial cells during shock, is reversed by resuscitation with hypertonic saline solu-tion but not improved by resuscitation with RL.…”

“…It has been shown that pial arteriolar diameter is decreased, relative to that of controls, 1 hour after resuscitation with RL but not with hypertonic saline solution. 21 Wahl et al 22 observed the effects of osmolarity on pial arteriolar diameter and found that constriction of pial arterioles occurs with osmolarity below 317 mOsm/L, and progressive dilatation occurs at osmolarities above this level. Loss of autoregulatory vasodilation in the ER group may have prevented CVR from decreasing, despite a decrease in blood viscosity.…”

“…6 Laboratory studies that recommend early, aggressive (prehospital) fluid resuscitation after hemorrhagic shock and head trauma make the assumption that COD is improved with asanguineous resuscitation. 21,[25][26][27] These studies were undertaken to evaluate the effects of different resuscitation fluids on cerebral hemodynamics, but none contained a DR group. This is the first study, to our knowledge, that evaluates cerebral hemodynamics following head injury and unresuscitated hemorrhagic shock.…”