Abstract Intravascular volume and pressure reflect hemodynamic status and are tightly correlated. Intensive care allows physiologic monitoring of these parameters—most on a continuous basis. Changes in volume and pressure must be interpreted in light of the underlying neurologic disorder. Hypovolemia is a potential clinical concern in virtually all patients with acute central nervous system injury. The paradigm of current fluid management—that is, aggressive fluid intake with crystalloids or colloids—has taken shape.