Carotid occlusion means that both carotid arteries are pinched off below the bifurcation; for about 10 seconds in the example shown here. This is done by gently lifting the sutures around the arteries. The carotid baroreceptors suddenly sense a profound drop in arterial pressure. This results in reflex activation of the sympathetic nervous system, including the adrenal medulla. The increase in blood pressure is caused mainly by generalized vasoconstriction and to a minor extent by increased cardiac output. The response is terminated quickly when the sutures are released. You should know the main mechanism of inactivation of nerve-released and circulating catecholamines.