Effects of Dexmedetomidine on Inflammatory Cytokines in Patients With Aneurysmal Subarachnoid Hemorrhage

Inclusion Criteria: * Aneurysmal subarachnoid hemorrhage * World Federation of Neurological Surgeons (WFNS) grade 4-5 (see table below) * Surgical intervention with clip or coil * Placement of cerebrospinal fluid drain (lumbar or ventricular) * Mechanically ventilated at start of infusion Exclusion Criteria: * Hemodynamic instability (SBP \< 100, HR \<60, or on continuous infusion of catecholamines) at screening * Heart failure class III or IV (New York Heart Association) * Renal failure (RIFLE classification - see table below) * Liver failure (serum protein \< 3 g/dL and total bilirubin \> 5 mg/dL) * Known or suspected brain death * Pregnancy * Unable to receive dexmedetomidine within 48 hours of injury and 4 hours of surgery * Allergy to dexmedetomidine * Prisoners