Mechanisms of hypoxaemia and the interpretation of arterial blood gases

Whilst there are many causes for hypoxia, an appreciation of the underlying physiology will assist in the correct diagnosis and management of this condition. This article describes the normal delivery of oxygen to the tissues, conceptual mechanisms of hypoxia and the clinical relevance of these pathological processes. Interpreting arterial blood gases (ABGs) is an essential part of managing sick patients and a logical method of reading ABGs is presented, alongside examples of deranged ABGs and the conditions causing these changes.