Supportive care for ischemic stroke patients has 2 main objectives: (1) to minimize injury to potentially ischemic brain tissue and (2) to prevent and treat the many neurologic and medical complications that may occur in the immediate period following stroke.
As cerebral blood flow drops below approximately 25 ml/100 gm tissue/min, neurons begin to malfunction, and neurologic symptoms become manifest, but normal function may be restored with reperfusion. As blood flow is reduced further, neurons begin to suffer irreversible damage. The extent of irreversible neuronal injury (ie, infarction) varies based on the degree and the duration of hypoperfusion (Hossman 1994). The region of cerebral tissue that is hypoperfused yet not irreversibly injured is referred to as the “ischemic penumbra.” Measures to increase cerebral perfusion may prevent permanent damage to this penumbral tissue. Furthermore, additional factors such as hyperglycemia, hyperthermia, and endothelial dysfunction may negatively impact salvage of the penumbra by accelerating neuronal damage. Many of the medical and neurologic complications to which stroke patients are susceptible may contribute directly (as in the case of cerebral edema) or indirectly (as in the case of infection causing fever) to neuronal injury. There is, therefore, considerable overlap between the goals of protecting neuronal tissue and preventing medical and neurologic complications.