Circulatory shock

Circulatory shock is the way a failure of the circulation shows itself, and it is life-threatening. Its result is hypoxia: cells and tissues are left without enough oxygen.

That hypoxia can come from three directions: less oxygen arrives, the tissues use more, or they can't make use of the oxygen that does reach them. And inside the cell, a problem starts that feeds on itself. The lack of oxygen produces acidosis, meaning the environment becomes acidic, and it also reduces blood flow to the affected area. With less flow, even less oxygen arrives. A vicious circle: lack of oxygen slows the very flow that would bring more. It's like a traffic jam: the fewer cars that make it through, the worse the backup gets, and even fewer get through.

At first the body fights back. The heart speeds up, which is tachycardia, and the vessels in the periphery narrow, which is peripheral vasoconstriction, to counter the fall in perfusion, the blood supply to the tissues. When those defenses are no longer enough, the organs begin to fail.