The systemic delivery and consumption of oxygen in the infant after cardiac surgery

Abstract

“All the vital mechanisms, however varied they may be, have only one object, that of preserving constant the conditions of life in the internal environment.”1An essential function of the cardiopulmonary system is to generate sufficient flow of oxygenated blood around the circulation in order to maintain normal cellular metabolism. The systemic delivery of oxygen is a function of the cardiac output and the content of oxygen in the systemic arterial blood, while the extent to which metabolising tissues require this oxygen for the maintenance of their integrity and function defines the systemic consumption of oxygen. As metabolising tissues have no mechanism for storing oxygen, they depend on its continuous supply, which must at least match their changing demands. As a result, it is a fundamental requirement of survival that the systemic consumption of oxygen, at all times, is matched by appropriate levels of its delivery.