Traumatic brain injury (TBI) is frequently associated with a hyperadrenergic state accompanied by elevated levels of plasma catecholamines. In its more severe presentation, the hyperadrenergic state presents as dysautonomia, which is characterized by paroxysmal alteration in vital signs, including tachycardia. The investigators hypothesize that intravenous (IV) esmolol is as effective at controlling heart rate in hyperadrenergic states as oral propranolol, which is the standard of care. Our primary endpoint is efficacy of IV esmolol vs a PRN regimen of intermittent B-blockade in controlling heart rate below a pre-specified level (< 100 bpm) after Traumatic Brain Injury (TBI) or hemorrhagic neurologic injury. Heart rates will be recorded continuously as well as hourly.