KEY LEARNING POINTS

• A thorough examination of the respiratory system will provide the diagnosis in most cases.
• Pulse oximetry, arterial blood gas sampling, chest X-rays and peak flow measurements are helpful tools.
• All critically ill patients should initially receive high flow oxygen (15 L/min Oxygen through a reservoir mask).
• Target oxygen saturations should be maintained using appropriate delivery devices, aiming for target saturations of 94-98% under normal circumtances or 88-92% in patients with chronically elevated partial pressure of carbon dioxide (e.g. Chronic Obstructive Pulmonary Disease) who rely on hypoxic drive to maintain adequate ventilation.