The Venturi mask: more than moulded plastic.

Supplemental oxygen therapy is central to the management of most acutely ill patients and many patients with chronic disease. Oxygen should be regarded as a drug and therefore be prescribed and administered with consideration. Fixed performance devices such as the Venturi masks and humidifier systems deliver a fixed fraction of inspired oxygen (FiO2) for a given oxygen flow rate. The indications, contraindications and hazards of oxygen therapy have been described by Booth (2006). This article aims to provide ammunition for the next ward round or clinical viva, by exploring both the physical principles behind these devices and celebrating the physicists whose names we use every day.