CIEMT Medical and Physiology Practice Exam

Cushing triad signals rising intracranial pressure and represents the brain's late reflexes to preserve cerebral perfusion. When ICP increases, cerebral perfusion pressure falls, so the body raises systemic blood pressure to keep blood flow to the brain, producing hypertension. The higher arterial pressure then elicits a reflex slowing of the heart, giving bradycardia. At the same time, brainstem irritation or compression disrupts normal breathing patterns, leading to irregular respirations. This combination—high blood pressure, slow heart rate, and irregular breathing—indicates a medical emergency with risk of brain herniation. Other patterns don’t fit because they lack one or more elements of this classic response; for example, hypotension would not reflect the compensatory rise in BP, tachycardia is not typical of this late brainstem-mediated response, and regular respirations imply preserved brainstem function rather than the disruption seen in the triad.