Cushing Reflex

The Cushing reflex (vasopressor response, Cushing reaction, Cushing effect, and Cushing phenomenon) is a physiological nervous system response to acute elevations of intracranial pressure (ICP), resulting in Cushing’s triad of widened pulse pressure (increasing systolic, decreasing diastolic), bradycardia, and irregular respirations. The Cushing reflex was proposed in 1901 by Dr. Harvey Cushing. He believed that the dramatic increase in blood pressure was a reflex to brainstem ischemia seen in patients with increasing ICP from causes such as intracranial hemorrhage, a mass effect from a tumor, and cerebral edema, to name a few. In cases of increased ICP, cerebral perfusion pressure (CPP) drops as the systolic blood pressure cannot overcome the resistance present in the brain. CPP is the pressure that pushes blood through the cerebrovascular network and is defined by the difference between mean arterial pressure (MAP) and intracranial pressure (ICP).