Nasal cannula/face mask application

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%.

Precautions

Oxygen is flammable. "No Smoking" signs should be posed when a patient is receiving oxygen. Electrical equipment must have special grounding adaptors on plugs to avoid sparks. The patient and family should be warned of the dangers involved in using oxygen at home, such as exercising care when using oxygen near stoves, portable heating units, and ungrounded electrical equipment. Oxygen cylinders must be place in a cart or base to avoid dropping or bumping the tank. Oxygen tanks or compressors should be turned off when not in use and oxygen valves should be checked routinely to be sure that they are secure. Oxygen levels in reserve tanks should be monitored to ensure continuous therapy.

Patients receiving oxygen should be closely monitored. Arterial blood gas analysis or the use of a pulse oximeter will ensure that the oxygen concentration being delivered is sufficient to meet the patient's needs. Monitor the patient's condition and vital signs frequently, according to the policy of the medical setting. The fit of the nasal cannula or mask and all of the oxygen connections should be evaluated, to ensure that no part of the system has been blocked or diverted and the oxygen is being delivered correctly, as ordered.

The use of a face mask can cause a patient to perspire and feel warm, claustrophobic or nauseated. Explain the importance of the oxygen to the patient and encourage him to relax and breathe slowly. A cold cloth on the forehead and moral support can help the patient overcome these anxious feelings. If a patient with an oxygen mask begins to vomit, quickly remove the mask. There is a danger of aspirating vomit into the lungs if it collects in the mask over the nose and mouth. Support the patient, assist them in cleaning the mouth after vomiting by rinsing with water or mouthwash, clean off the mask and the attached tubing, and replace it. The physician should be notified and antiemetics may be ordered.

A nasal cannula is more comfortable for a patient than a mask but can only deliver low concentrations of oxygen. Nasal cannulas should only be used in patients who breathe adequately through their noses. Use of cannulae is not indicated in patients who have severe hypoxia, poor respiratory effort, blocked nasal passages, apnea, or are mouth breathers.

Be cautious about giving oxygen to patients with chronic obstructive pulmonary disease because they may retain carbon dioxide. Oxygen may depress the hypoxic drive in these patients. They should be observed for decreased respirations, an altered mental state or further elevations of their carbon dioxide levels.

Description

Before applying a nasal cannula, the oxygen-flow meter should be turned to the setting in liters per minute that is ordered by the physician. The nurse should use his or her finger tips to ensure that oxygen is flowing through the prongs of the cannula. The nurse should apply a nasal cannula by placing the nasal prongs gently into the patient's nostrils, draping the tubing over the patient's ears, and sliding the fit connector up under the chin to hold the tubing securely in place. Two small pieces of clear plastic tape can be used to hold the cannula against the patient's cheeks to secure the cannula in place if necessary. This is only necessary if the patient is restless, confused, or is a young child who may bat the cannula out of place.

Before applying an oxygen face mask, the nurse should turn on the oxygen flow-meter to the setting in liters per minute that is ordered by the physician. If using a Venturi mask, the adaptor device should be selected and applied to deliver the oxygen concentration that is ordered. Use the finger tips to ensure that oxygen is flowing through the face mask. An oxygen face mask is applied by placing the molded plastic mask onto the patient's face, over the nose and mouth. The nurse should pull the elastic strap over the patient's head to the back of the head and adjust the strap on both sides of the mask to secure the mask in a position that seals it against the face. Some masks have a nose-clip that can be gently squeezed to mold the mask over the bridge of the nose. The mask should fit snugly against the face but must not press so tightly as to leave impressions in the skin. If the mask has a reservoir bag and its purpose is to serve as an oxygen reservoir, the nurse should check that oxygen is filling the bag before applying the mask.

Preparation

The nurse should place the patient in a comfortable position, preferably semi-Fowler's or full Fowler's position (to assist breathing). She or he should take baseline vital signs and note the patient's level of consciousness. A pulse-oximetry reading or draw blood gases should be done as ordered for baseline lab values. Oxygen delivery to the patient should be explained, including what equipment is to be used (such as a mask or nasal cannula) and the importance of keeping the apparatus in place. The patient should know of the flammability of oxygen and a "No Smoking" sign should be posted. The nurse should instruct the patient to notify him or her of increasing distress, air hunger, nausea, anxiety , dry nasal passages, or "sore throat" (due to drying). The equipment needed should be assembled, including the oxygen-flow meter, humidity bottle if ordered, nasal cannula, or appropriate face mask. The mask or cannula should be connected securely to the oxygen flow-meter. Extension tubing should be used between the mask tubing and the oxygen flow-meter if necessary so that the patient may move about without pulling the mask off or pulling the tubing out of the oxygen source. The nurse should place a pulseoximeter machine at hand if ordered, to monitor the patient's response to oxygen therapy .

Aftercare

After initiating oxygen therapy, the nurse should stay with the patient for a while to reassure the patient and observe his or her reactions to the therapy. The patient's vital signs should be monitored, along with the level of consciousness, comfort with the oxygen apparatus, and oximetry levels, as ordered by the physician or as directed by policy of the medical setting. Oxygen connections and settings should be checked. The nurse should observe the patient, either for improvements in color, respiratory rate and rhythm, and comfort levels, or for increased or decreased respiratory effort, diaphoresis, alteration in mental status, anxiety and restlessness. Facemasks will interfere with communication and eating. Oxygen will dry out the mucous membranes of the nose and mouth. The nurse should briefly remove the mask periodically to allow the patient to drink or eat, for mouth care, or to communicate clearly. When the mask or cannula is off, the skin on the face and above the ears should be checked for signs of skin irritation. If the skin is irritated

KEY TERMS

Antiemetic —A medication given to decrease nausea and prevent vomiting.

Apnea —The absence or cessation of breathing.

Diaphoresis —Profuse sweating that is often medically induced.

Hypoxemia —Insufficient levels of oxygen in the blood.

Hypoxia —Air hunger or insufficient oxygen to the body tissue.

Endotracheal intubation —The process of inserting a soft plastic cuffed or uncuffed tube through the mouth or nose, past the epiglottis into the bronchus.

Mechanical ventilation —Artificial respiration provided by a machine that delivers pressurized oxygen, either automatically or on demand, to expand the lungs during inhalation, and provides passive resistance during exhalation at a set rate.

Narcosis —A condition of confusion, stupor or unconsciousness caused by a medication, chemicals, lack of oxygen, or a build up of toxins (such as carbon dioxide) in the blood.

Pulse oximeter —A small machine that continuously measures the oxygen saturation of the circulating blood, usually through a finger clamp with an oxygen-sensitive surface that is placed over the nail bed of a finger or toe.

above the ears, cotton padding can be placed between the ears and the elastic band or the cannula tubing to protect the skin. If the skin of the face is irritated, the face can be massaged gently and a water-based moisturizer applied. The mask can be loosened slightly to decrease irritation. The use of petroleum ointment to the lips or nose should be avoided because it can obstruct the cannula prong openings. If a humidifier is used with the oxygen apparatus, the humidity bottle should be refilled with distilled water according to the medical setting routine or at least once every eight hours. Blood gas analysis should be done as ordered when a patient is receiving oxygen to determine whether levels of oxygen flow should be decreased or need to be increased. When higher levels of oxygen are no longer needed, a patient using a face mask should be changed to a nasal cannula to improve comfort, the ability to communicate, and the ability to eat and drink more easily during therapy.

Complications

The most serious complication of oxygen therapy is the depression of the hypoxic drive to breathe in patients with chronic lung disease. High levels of oxygen may cause elevated levels of trapped carbon dioxide, which may lead to a decrease in respirations, a state of narcosis, and eventually to respiratory stasis or arrest.

Less serious complications include skin breakdown around the mask or cannula, a dry mouth, nose or lips, sore throat , and a decrease in appetite.

Results

Oxygen therapy using a nasal cannula or facemask is usually effective in increasing oxygen levels in the body to a normal or near normal state, providing time for treatment of the underlying disease or impediment causing the hypoxemia. Patients who do not respond to non-invasive oxygen therapy will usually be intubated (endotracheal intubation) and placed on mechanical ventilation with oxygen either as an assist device or as a full-capacity respirator.

Health care team roles

Oxygen is considered a drug and in this context is administered by a licensed nurse or respiratory therapist in the medical setting. Once oxygen therapy has been initiated, non-professional staff may assist in caring for the patient using oxygen therapy, including removing and replacing the mask or cannula for skin care, meals or brief ambulation to the bathroom. Nonprofessional staff must be instructed to remember to turn the oxygen flow back on after removal. They may also be trained to check oxygen apparatus such as, checking tubing connections, replacing the oximeter probe, filling the humidity bottles and cleaning or wiping humidity out of the oxygen mask. This should be performed under the direct supervision of the licensed nurse and the nurse or respiratory therapist will continually assess the patient's respiratory status and oxygen levels. When a patient is going home with oxygen, the licensed nurse or respiratory therapist will educate the patient and the patient's caregivers about the safe use of oxygen in the home. Patients using oxygen in the home should have initial and follow-up visits by a home care nurse or respiratory technician to check the patient's status and equipment function in the home. Patients receiving oxygen in the home should be scheduled for regular visits to the physician for follow-up assessment, including pulse oximetry and other therapy.

Resources

BOOKS

"Oxygen Delivery Systems." In The Harriet Lane Handbook, 15th ed. Ed. by George K. Siberry and Robert Iannone. Mosby, Inc., 2000.

OTHER

"Airway Management." Respiratory Therapist. Continuing Education Online. June 2000. <http://www.continuingeducation.com/resptherapist/airway/supadmin.html>.

Auerbach, Paul S., M.D. "Oxygen Administration." Medicine for the Outdoors. Adam.com Online. The Lyons Press, 1999. <http://www.adam.com/b2b/products/demos/odh/oxygen_admin.html>.

"Inpatient Oxygen Therapy." Standards for the Diagnosis and Care of Patients with Chronic Obstructive Pulmonary Disease. American Thoracic Society. Epocnet Online. 200l. <http://www.epocnet.com/area_m/normas/b_4_03f.html#up>.

"Oxygen Administration." Nursing Interventions and Clinical Skills. 2nd ed. Harcourt Health Online. Mosby, Inc.,2000. <http://www.harcourthealth.com/MERLIN/Elkin/Skills/31-01.html>.

"Respiratory Function and Therapy," Chapter 10. In The Lippincott Manual of Nursing Practice. Books at Ovid Online. 2001. <http://pco.ovid.com/lrppco/>.

Mary Elizabeth Martelli, R.N., B.S.