ABC of major trauma. Management of severe burns.

Abstract

Hypovolaemic shock is a clinical state in which tissue perfusion is rendered relatively inadequate by loss of blood or plasma after injury to the vascular tree. A reduction in blood volume produces a fall in systolic pressure, which triggers a sympathetic catecholamine response that results in peripheral vasoconstriction, a rise in pulse rate, and a reduction in pulse pressure. The tachycardia and increased cardiac contractility lead to an increased myocardial oxygen requirement. Blood flow to the skin and peripheral tissues is reduced in an effort to preserve reasonable perfusion of vital organs such as the brain, heart, liver, and kidneys. If there is continuing blood loss inadequate tissue perfusion results in anaerobic mnetabolism, acidosis, and reduction in the performance of the vital organs. Further myocardial depression accelerates this process, and pain stimuli add to the sympathetic outburst.