Cushings reflex = a hypothalamic response to brain ischemia wherein the sympathetic nervous system is activated which causes increased peripheral vascular resistance with a subsequent increase in BP. The increased BP then activates the parasympathetic nervous system via carotid artery baroreceptors, resulting in vagal-induced bradycardia. The brain ischemia that leads to cushings reflex is usually due to the poor perfusion that results from increased ICP due to head bleeds or mass lesions. Cushings reflex leads to the clinical manifestation of Cushings triad. Cushings triad = hypertension, bradycardia, and irregular respirations (Cheyne-Stokes breathing). Some sources describe widened pulse pressure (increasing difference between systolic and diastolic BP) as the 3rd component of the triad, rather than irregular respirations. Cushings triad signals impending danger of brain herniation, and thus, the need for decompression. Consider administering mannitol, hyperventilation, and elevation of the head of bed as temporizing measures. Cushings triad was first described in 1902 by Harvey Williams Cushing, an American neurosurgeon. -Physiology, 2nd Edition, Saunders, 2002, page 150. -Ayling, J (2002). "Managing head injuries". Emergency Medical Services31 (8): 42.
