Oxygen delivery and resuscitation

Abstract

Modern concepts of oxygen delivery date from the work of Joseph Barcroft, who in 1920 classified deficits of oxygen delivery as "anoxic" when the blood is not filled with oxygen, "anemic" when hemoglobin concentration is low, or "stagnant" when blood flow is inadequate. These three pathologic states may occur singly or in combination, and may be quantitated by the expression: Oxygen delivery = cardiac output X arterial oxygen content Oxygen delivery is an extremely important physiologic concept for resuscitating critically ill patients because tissue availability of oxygen is totally dependent on oxygen delivery. However, other physiologic alterations also can alter tissue use of oxygen, even in the presence of adequate oxygen delivery. These include alterations of oxyhemoglobin dissociation, alterations in microcirculatory blood flow, the presence of carbon monoxide, and mitochondrial dysfunction. The major goal of resuscitation of seriously ill and injured patients is to provide them with sufficient oxygen to meet their metabolic requirements. These needs are significantly increased following shock, injury, and illness. Only by meeting these increased cellular oxygen demands can adequate cellular function be maintained and organ failure avoided.