Nasal Cannula/Face Mask Appli... Health Article

Definition

A nasal cannula is a narrow, flexible plastic tubing used to deliver oxygen through the nostrils of patients using nasal breathing. It connects to an oxygen outlet, a tank source or compressor, on one end and has a loop at the other end with dual pronged extended openings at the top of the loop. The prongs are slightly curved to fit readily into the front portion of a patient's nostrils. The tubing of the loop is fitted over the patient's ears and is brought together under the chin by a sliding connector that holds the cannula in place.

A simple oxygen face mask is a plastic device that is contoured to fit over a patient's nose and mouth. It is used to deliver oxygen as the patient breathes through either the nose or the mouth. A simple oxygen mask has open side ports that allow room air to enter the mask and dilute the oxygen, as well as allowing exhaled carbon dioxide to leave the containment space. It also has narrow plastic tubing fixed to the bottom of the mask that is used to connect the mask to an oxygen source. An adjustable elastic band is connected to each side of the mask and slides over the head and above the ears to hold the mask securely in place.

A partial rebreather oxygen mask is similar to a simple face mask, however, the side ports are covered with one-way discs to prevent room air from entering the mask. This mask is called a rebreather because it has a soft plastic reservoir bag connected to the mask that conserves the first third of the patient's exhaled air while the rest escapes through the side ports. This is designed to make use of the carbon dioxide as a respiratory stimulant.

A non-rebreather oxygen mask is similar to a simple face mask but has multiple one-way valves in the side ports. These valves prevent room air from entering the mask but allow exhaled air to leave the mask. It has a reservoir bag like a partial rebreather mask but the reservoir bag has a one-way valve that prevents exhaled air from entering the reservoir. This allows larger concentrations of oxygen to collect in the reservoir bag for the patient to inhale.

A Venturi oxygen mask is similar to a simple face mask but the tubing that connects to the oxygen source is larger than that of other masks. The connector has interchangeable adaptors that widen or narrow the diameter of the flow through the tubing to allow settings of specific concentrations of oxygen through the mask.

Purpose

The purpose of nasal cannulas and oxygen face masks is to deliver oxygen in as concentrated a form as required for patients who are hypoxic. There are many conditions that cause hypoxemia and require the administration of supplemental oxygen, including respiratory disease, cardiac disease, shock, trauma, severe electrolyte imbalance (hypokalemia), low hemoglobin or severe blood loss, and seizures. Prompt treatment of these conditions with non-invasive oxygen administration can prevent the need for more invasive procedures such as intubation and mechanical ventilation.

A nasal cannula is used to deliver low concentrations of oxygen. It can deliver from 24% to 40% oxygen at a flow rate of 0.26-1.58 gal (1-6 L) per minute. A simple mask is used to deliver moderate to high concentrations of oxygen. It can deliver from 40% to 60% oxygen at a flow rate of 2.64-3.17 gal (10-12 L) per minute. A partial rebreather mask is used to deliver high concentrations of oxygen. It can deliver 70% to 90% oxygen at a flow of1.58-3.96 gal (6-15 L) per minute. A non-rebreather mask is used to deliver high flow oxygen. It can deliver 90% to 100% oxygen at a flow of 3.96 gal (15 L) per minute. A variable flow rate mask has interchangeable adaptors that may be set to deliver oxygen at 24%, 28%, 31%, 35%, 40%, or 50%.