This is a pilot study to test the hypothesis that conivaptan (Vaprisol) leads to a greater increase in sodium than usual care. Patients will be randomly assigned to usual care or the lower FDA-approved dose of conivaptan (Vaprisol). We will track the use of other interventions, such as the use of hypertonic saline (concentrated salt solution), diuretics and salt tablets. A blinded co-investigator will record neurologic examination results (NIH Stroke Scale and Glasgow Coma Scale).