The differences between a nasal cannula and an oxygen mask when using oxygen therapy
Both nasal cannulas and oxygen masks allow the delivery of oxygen in a concentrated form to people who are hypoxic – inadequate oxygen supply to body tissues. Many conditions cause hypoxaemia including COPD, respiratory disease, shock, trauma and cardiac disease.
So which one
Generally nasal cannulas are the preferred intake method of oxygen to the body. Their slimline shape allows you to move about and perform normal duties with little hindrance. Also cheap to replace (We recommend monthly for most users).
A face mask can be used if you find cannulas uncomfortable but will be better suited to a stationary situation such as sitting or in bed.
A nasal cannula allows the delivery of oxygen concentrations of between 24 to 40% at flow rates between 1 to 6LPM – making them suitable for use with most portable oxygen concentrator units. One end of the plastic tubing is equipped with curved nasal prongs which fit into the front of the nostrils, with the loop hooked over the ears and the end attached to an oxygen source.
A face mask as the name suggests fits over the face. The extent to which the face is covered depends on the type/purpose of the face mask. A simple face mask fits over the nose and mouth with open side ports to allow air to enter and dilute the oxygen as well as allow the escape of carbon dioxide. The mask is attached via an elastic strap which fits behind the head and over the ears with the end of the tubing attached to an oxygen source. A face mask allows oxygen delivery via either the nose or mouth so is suitable for nose and or mouth breathers.
Apart from the physical differences of each device, the primary difference is that face masks allow higher concentrations and rates of flow of oxygen. A simple face mask can deliver oxygen concentrations from 40 to 60% at flow rates between 10 to 12LPM. A partial rebreather mask has side ports that are covered with single way discs that prevent room air entering. A soft plastic bag connected to the mask stores the first third of exhaled air with the rest escaping through the side. The rebreather mask makes use of the exhaled carbon dioxide to stimulate respiration.
As a result different styles of rebreather masks can deliver oxygen concentrations from 40 to 100% at varying flow rates from10 to 15LPM.