Mechanisms of hypoxaemia and the interpretation of arterial blood gases

Hypoxaemia has many potential causes and an appreciation of the underlying physiological mechanisms is useful for the diagnosis and management of this common clinical condition.This article will explain the stages by which oxygen is delivered to the tissues, conceptual mechanisms of different types of hypoxia, and the clinical relevance of these different pathological processes (with examples).An understanding of arterial blood gas (ABG) analysis is an essential part of managing unwell patients and a logical method of approaching ABG interpretation is presented here. Examples are presented of common conditions leading to derangement of those values measured by the blood gas machine.