Interpretation of measurements of arterial blood gases

Measurement of arterial blood gases (ABG) is one of the commonest clinical investigations in emergency, perioperative and critical care. Analysis of ABG measurements can provide information about cardiopulmonary function and biochemical homeostasis that may be invaluable for diagnosis and monitoring therapeutic interventions. Interpretation of ABG measurements is often viewed as complicated and confusing. The aim of this contribution is to describe the underlying physiological mechanisms and provide a stepwise approach to interpretation.