 The seven patients in this study will receive 40mgday of the study medication conivaptan. In this early phase study, our focus will be to assess the safety and tolerability of this medication. The available clinical data on conivaptan in the neurocritical care population suggest the potential harm is negligible. Data in TBI patients demonstrate conivaptan is safe and well tolerated using a single dose 20mg to increase Na in a controlled fashion to reduce ICP. Previous work has demonstrated the safety and tolerability of conivaptan, in doses ranging from 20-80mgday, in the neurocritical care population. Conivaptan has been demonstrated to be safe and effective in lowering ICP, and increasing serum sodium, in the neurocritical care population. Also noted have been improvements in cerebral perfusion pressure CPP and stable blood pressure, and a prolonged reduction in ICP. Finally, the method of intermittent bolus dosing of conivaptan is equally effective in raising and maintaining serum sodium in the neurocritical care population as continuous infusion, with potentially less risk of adverse reactions including phlebitis. 