Lead Sponsor

Johns Hopkins University

Age

18 - 100 years

Sex

ALL

Healthy Volunteers

No

•TBI (Moderate/Severe TBI (GCS 12 or Head AIS\>1) or hemorrhagic neurologic injury
•Hyperadrenergic Activity: At least one paroxysmal episode (lasting at least 15 minutes) of Heart Rate 110 beats per minute during two or more consecutive days plus at least two more of the following that may not be better explained by another disease process (ex: sepsis):
•Temperature of 38.5C Respiratory Rate 20 breaths per minute Agitation Diaphoresis Dystonia Stimulus responsive ("triggering of paroxysm")
•\- Informed Consent obtained

•Patients that do not meet criteria for dysautonomia (as stated above)
•Age \<18 years
•Pregnancy
•Hypotension - requiring pressor therapy to maintain baseline adequate CPP or mean arterial pressure
•Cardiac arrhythmia - sinus bradycardia (HR \<60), 2nd or 3rd degree AV block
•Hemodynamic contraindications to intravenous beta-blockade such as a documented history of congestive heart failure (CHF), dependency on cardiac inotropes or documented bronchospastic disease
•Any patient on chronic beta blockade as an outpatient.
•Life expectancy \< 48 hours or patients with "do not resuscitate orders"
•Ongoing seizure activity
•Informed consent not obtained