Severe traumatic brain injury with increased intracranial pressure can lead to decreased cerebral blood flow. Low cerebral blood flow is responsible for secondary lesions, leading to bad prognosis. It is not yet established whether increasing cardiac output in these patients can lead to an increase in cerebral blood flow, although there are some arguments in favor of this hypothesis. The aim of this study is to demonstrate that increasing cardiac output will improve cerebral blood flow in patients with severe traumatic injury and high cerebral pressure.