The primary objective of this study is to determine in patients with traumatic brain injury (TBI) the safe dosing of propranolol. Safety will be measured by episodes of bradycardia (heart rate < 60 beats per minute), hypotension (defined as systolic blood pressure < 90) or decreased cerebral perfusion pressure (defined as CPP less than 60mmHg) that are refractive to Brain Trauma Foundation guidelines for treatment. A no-treatment arm will establish the number of episodes of bradycardia, hypotension and reduced cerebral pressure refractory to treatment that occur without propranolol.

Inclusion Criteria:

• patients who present within 6 hours of traumatic brain injury who have 1) a Glasgow Coma Scale (GCS) score of ≤8 or a GCS of 9-12 with computerized tomography brain scans demonstrating brain injury.

Exclusion Criteria:

• pregnancy,
• patients already treated with beta-blockers,
• patients treated for antiarrhythmic, immunosuppressive or antiinfective treatment,
• myocardial infarction during the last 3 months,
• unstable or severe heart disease,
• severe chronic obstructive pulmonary disease,
• serious liver disease,
• cardiac ischemia that prevents the initiation of vasopressors,
• signs of cardiac arrhythmia or heart block on EKG,
• ischemic limb disease that prevents the initiation of vasopressors, vasopressors at maximum dose defined as norepinephrine at 40µg/min or neosynephrine at 300µg/min.