Le Dorze M, et al. - Researchers investigated if, after a positive response to fluid challenge (FC), systemic inflammation (severe sepsis or septic shock) changes the control of brain circulation and the relationship between systemic and cerebral hemodynamic. They studied 3 groups of patients if they increased stroke volume (SV) > 10% after 250 or 500 ml of crystalloids: a control group consisting of patients free of comorbidity anesthetized for orthopedic surgery, a sepsis group consisting of patients with severe sepsis or septic shock (classic definition), and a brain injury (BI) group consisting of patients having trauma brain jury or hemorrhagic stroke with no detectable systemic inflammation. Only patients exhibiting sepsis-induced severe acute systemic inflammation showed increase in SV (and cardiac output) after FC increased systolic and diastolic middle cerebral artery velocity. In severe acute systemic inflammation, the impact of a systemic blood flow increase on cerebral flow velocities predominates the role of mean arterial pressure rise.