Traumatic brain injury (TBI) is among the leading causes of trauma death and disability in both civilian and military populations. The damage that occurs at the instant of trauma cannot be modified; the secondary injuries that occur afterward are the impediments to recovery and can be influenced by the physician. Cerebral ischemia is the most important secondary event that determines outcome following TBI. To minimize ischemic episodes once the patient has arrived at the hospital, most treatments are aimed at optimizing cerebral perfusion pressure (CPP). The cornerstones of these treatments include mannitol, to reduce intracranial pressure (ICP), and catecholamines, such as phenylephrine (PE), to increase mean arterial pressure (MAP), but these agents have undesired side effects. Nevertheless, once they lose potency, there are few alternatives. The main objective of this proposal to develop a new therapeutic option for CPP management in TBI patients using arginine vasopressin (AVP).

AVP is the endogenous anti-diuretic hormone. It is FDA-approved for use in the diagnosis and treatment of diabetes insipidus, for the prevention and treatment of post-operative abdominal distention, and in abdominal radiography to dispel interfering gas shadows. It has been used off-label for several other conditions. There is minimal information on its therapeutic potential after TBI. The investigators have demonstrated that AVP during fluid resuscitation rapidly restored hemodynamics, CPP, and improves acute survival in a clinically-relevant model of TBI. The investigators observed similar short term benefits after chest and liver trauma. Nevertheless, AVP has actions that could mask any short term benefit. The investigators have already defined risks and benefits of AVP therapy, relative to PE, in four different clinically-relevant laboratory model. The investigators now plan to evaluate this new therapy relative to the current evidence-based guideline for CPP management in TBI patients.

The working hypothesis is that the risk/benefit profile for AVP is equal, or superior to, PE at equi-effective doses for the management of CPP following TBI. A corollary is that a higher CPP can be safely tolerated with AVP vs catecholamines.

THE INVESTIGATORS AIM TO: Determine whether AVP is safe and effective to maintain CPP = 60 mm Hg in TBI patients.