Which parameter is increased during Cushing's Reflex as a compensatory mechanism?

• A. Mean Arterial Pressure
• B. Heart Rate
• C. Respiratory Rate
• D. Cardiac Output

Answer: (A)

When intracranial pressure rises, cerebral perfusion pressure drops. The body's response is to raise arterial pressure to keep enough blood flow to the brain. This compensatory increase in mean arterial pressure helps maintain cerebral perfusion pressure (CPP = MAP − ICP) despite the high ICP. That rise in MAP is the key change seen in the Cushing reflex.

You’ll often also see the heart rate slow down (bradycardia) because of the baroreceptor response to higher blood pressure, and respirations may become irregular as brainstem function is affected. Cardiac output isn’t the primary reflexive target here, while the crucial, defining shift is the increase in mean arterial pressure.