Oxygen Therapy: Nasal Cannula or Oxygen Mask - CE/NCPD

ALERT

Oxygen is considered a medication and requires a practitioner’s order; administer it cautiously and observe the patient closely for adverse reactions. Assess the patient’s need for oxygen and recognize the signs and symptoms of hypoxemia.

Use caution in the presence of oxygen. Oxygen is a fire hazard because it lowers the temperature at which materials catch fire in the presence of an ignition source, such as a spark or heat from a light source.

Respiratory depression can develop in a very small percentage of patients who are chronically hypercapnic when breathing moderate to high oxygen concentrations.^{undefined#ref1">1}

OVERVIEW

The goal of oxygen therapy is to maintain adequate levels of oxygen to manage suspected or confirmed hypoxemia and prevent hypoxia. Selection of the type of oxygen therapy is based on the patient’s need, the severity of hypoxemia, and the disease process. Signs and symptoms of mild hypoxia include restlessness, anxiety, disorientation, confusion, and fatigue (Box 1) Box 1 .

The two types of oxygen delivery devices are high flow and low flow. High-flow devices decrease the entraining of room air, which can dilute the fraction of inspired oxygen (FIO₂).

The target peripheral oxygen saturation (SpO₂) for most acutely ill patients is 94% to 98%.¹ Patients with chronic obstructive pulmonary disease should have a target of 88% to 92%.¹

Oxygen Therapy

Devices that deliver oxygen therapy include a nasal cannula, various types of face masks, and oxygen tents and hoods (Table 1) Table 1 .

A nasal cannula is a simple, effective, comfortable device for delivering low-flow oxygen (Figure 1).¹ It consists of two prongs protruding from the center of a disposable tube and inserts into the nostrils. The nasal cannula allows breathing through the mouth or nose, is available for all age groups, and is adequate for short- or long-term use. Compared with other oxygen delivery systems, a nasal cannula decreases a patient’s feeling of claustrophobia, but it may not be suitable for mouth breathers. Cannulas are inexpensive, disposable, and easily accepted by most patients. When cannulas are used at higher flow rates, the airway mucosa may dry. A humidifier filled with sterile water should be used to help prevent drying of the nasal and oral mucous membranes if the flow rate is greater than 4 L/min.¹ Approximate FIO₂ is estimated by the flow rate. The delivered oxygen percentage varies, depending on the rate and depth of the patient’s breathing.¹

A simple face mask is for short-term, low-flow oxygen therapy (Figure 2).¹ A clear plastic mask is placed on the patient’s face with an elastic strap to secure it. The body of the mask stores oxygen between the patient’s breaths. Side port openings located on either side of the mask allow room air to mix with delivered oxygen and allow exhaled air to escape. The percentage of delivered oxygen varies, depending on the rate and depth of the patient’s breathing.¹ Using a simple mask with a flow rate less than 5 L/min causes the mask volume to act as dead space and causes carbon dioxide rebreathing.² Some patients find the face mask uncomfortable, and it must be removed for eating.

A partial rebreathing mask is a face mask with a reservoir bag that delivers moderate to higher concentrations of oxygen (Figure 3A).¹ Frequent inspection of the reservoir bag is required to ensure that it remains inflated; if it is deflated, exhaled air collects in it, which results in the patient rebreathing large amounts of exhaled carbon dioxide. Side port openings on either side of the mask vent exhaled air on expiration and allow room air to enter the mask on inspiration. The delivered oxygen percentage varies, depending on the rate and depth of the patient’s breathing.¹

A non-rebreathing mask is a face mask with a reservoir bag that delivers high concentrations of oxygen (Figure 3B).¹ A one-way inspiratory valve sits on top of the reservoir bag, and a one-way expiratory valve covers one of the side ports on the mask. During inhalation the expiratory valve over the side port closes, preventing air from entering the mask while the inspiratory valve on top of the reservoir bag opens, providing oxygen to the patient. During exhalation, the expiratory valve opens allowing exhaled air to vent out of the mask while the inspiratory valve closes preventing exhaled air from entering the reservoir bag. The open exhalation port is a safety feature designed to allow air to enter the mask if the oxygen source fails. However, this feature can result in dilution of the inspired oxygen. The delivered oxygen percentage varies, depending on the rate and depth of the patient’s breathing.¹

A face tent is a shieldlike device that fits under the patient’s chin and encircles the face (Figure 4). It is used primarily for humidification and for oxygen only when the patient cannot or will not tolerate a tight-fitting mask. Because it is not close to the patient’s face, estimating how much oxygen is delivered to the patient is not possible.

High-Flow Oxygen Therapy

A Venturi mask is a cone-shaped device with entrainment ports of various sizes at its base (Figure 5).¹ The entrainment ports adjust to deliver various oxygen concentrations. This mask is useful because it delivers a more precise concentration of oxygen to the patient.

High-flow nasal oxygen therapy is a method of providing warmed, humidified oxygen at higher concentrations via specialized nasal cannula (Figure 6). Conventional nasal cannula devices can deliver flows of only 1 to 6 L/min, whereas high-flow nasal oxygen therapy delivers flows from 1 L/min to 50 L/min, depending on the device.¹ High-flow oxygen therapy allows for more effective secretion clearance, decreases atelectasis, and prevents dehydration of the airway mucosa.

SUPPLIES

See Supplies tab at the top of the page.

EDUCATION

Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
Provide the patient and family with an explanation of the equipment and the procedure.
Inform the patient and family that any oxygen delivery device may irritate the skin and instruct them to inspect the skin frequently and report any changes in appearance.
Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

Perform hand hygiene before patient contact. Don appropriate personal protective equipment (PPE) based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
Introduce yourself to the patient.
Verify the correct patient using two identifiers.
Assess the patient’s respiratory status, including the symmetry of chest wall expansion, respiratory rate and depth, sputum production, and breath sounds.
Assess the patient for signs and symptoms of hypoxia (Box 1).
Observe the patient for behavioral changes (e.g., apprehension, anxiety), decreased level of consciousness (LOC), or light-headedness.
Assess the patient’s airway patency. If secretions are present, encourage the patient to cough or suction the airway.
Evaluate the patient’s vital signs and the SpO₂ value.
Evaluate the patient’s most recent arterial blood gas (ABG) results, if available.
Inspect the condition of the patient’s skin around the nose and ears.

Preparation

Verify the order for oxygen therapy, noting the delivery method and flow rate.

PROCEDURE

Oxygen Therapy

Perform hand hygiene and don gloves. Don additional PPE based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
Verify the correct patient using two identifiers.
Explain the procedure and ensure that the patient agrees to treatment.
Set up the oxygen delivery system.
1. Attach the oxygen flowmeter to the oxygen source (Figure 7).
  Verify that the flowmeter is connected to oxygen, not air or another gas. Connecting the flowmeter to a gas other than oxygen can have fatal consequences.
2. Attach the humidifier to the oxygen flowmeter, if needed.
  Rationale: Humidity prevents drying of nasal and oral mucous membranes and airway secretions. Humidification should be used if the liter flow rate is 4 L/min or greater.¹
3. Attach the oxygen delivery device (i.e., cannula, mask) via the oxygen tubing to the humidifier or directly to the oxygen flowmeter via the flowmeter adaptor.
Adjust the oxygen flowmeter to the prescribed flow rate (Figure 7).
Position the oxygen delivery device on the patient’s face and adjust the elastic headband (or behind-ear loops and under-chin lanyard of the cannula) to achieve a comfortably snug fit. Maintain enough slack on the oxygen tubing.
Rationale: The patient is more likely to keep the device in place if it fits comfortably.
1. Nasal cannula: Ensure proper positioning of the cannula tips in the patient’s nares. If the cannula tips are curved, ensure that they point downward (Figure 1).
  Rationale: Ensuring proper positioning of the cannula tips directs oxygen flow into the patient’s upper respiratory tract. Looping the cannula around the patient’s ears reduces pressure on the nares.
2. Simple face mask: Ensure that the mask is over the patient’s mouth and nose, forming a seal (Figure 2).
3. Partial rebreathing mask: Ensure that the mask is over the patient’s mouth and nose, forming a tight seal. Also ensure that the reservoir bag remains partially inflated on inspiration (Figure 3A).
4. Non-rebreathing mask: Ensure that the mask is over the patient’s mouth and nose, forming a tight seal. Ensure that both one-way valves at the side ports are in place to maintain a full non-rebreather system. Also ensure that the reservoir bag remains partially inflated on inspiration (Figure 3B).
5. Venturi mask: Ensure that the mask is over the patient’s mouth and nose, forming a tight seal, and that the appropriate port has been selected (Figure 5).
  Rationale: A tight seal reduces carbon dioxide retention.
6. Face tent: Ensure that the tent fits under the patient’s chin and over the mouth and nose (Figure 4).
  Rationale: The tent fits loosely, and a mist is always present.
Verify that the oxygen delivery device is functioning properly.
Rationale: Verification ensures patency of the delivery device and accuracy of the prescribed oxygen flow rate.
Discard supplies, remove PPE, and perform hand hygiene.
Document the procedure in the patient’s record.

High-Flow Nasal Cannula Oxygen Therapy

Perform hand hygiene and don gloves. Don additional PPE based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
Verify the correct patient using two identifiers.
Explain the procedure and ensure that the patient agrees to treatment.
Position the nasal cannula on the patient’s face and adjust the head strap to achieve a comfortably snug fit. Follow the manufacturer’s instructions for application.
Ensure proper positioning of the cannula tips in the patient’s nares. If the cannula tips are curved, ensure that they point downward. Maintain enough slack on the oxygen tubing.
Review the high-flow oxygen delivery device settings, use of humidifier and heater, and alarms with the respiratory therapist.
Verify that the oxygen delivery device is functioning properly.
Rationale: Verification ensures patency of the delivery device and accuracy of the prescribed oxygen flow rate.
Discard supplies, remove PPE, and perform hand hygiene.
Document the procedure in the patient’s record.

MONITORING AND CARE

Observe the oxygen delivery device frequently to ensure proper placement. Readjust as necessary.
Monitor the patient’s vital signs and SpO₂ level and when making changes in oxygen therapy. Notify the practitioner of any signs of deterioration.
Rationale: Clinical deterioration of a patient receiving high-flow nasal oxygen is a medical emergency given the acuity of the patient and the potentially minimal respiratory reserve.³
Check the humidifier when taking vital signs.
1. Low-flow oxygen therapy: Replace the humidifier when it is empty.
2. High-flow oxygen therapy: Notify the respiratory therapist when it is almost empty.
Observe the skin of the patient’s outer ears, back of the head, bridge of the nose, nares, and nasal mucous membranes for evidence of pressure injuries or drying.
Rationale: Oxygen therapy may cause drying of the nasal mucosa. The delivery device may cause pressure injuries where it comes in contact with the face, neck, head, and ears.

EXPECTED OUTCOMES

The signs and symptoms of hypoxemia are reduced or eliminated.
The patient’s vital signs remain stable.
The patient experiences a decrease in work of breathing.
The patient tolerates the oxygen delivery device without difficulty.
The oxygen delivery device fits properly.
The patient has no facial irritation or skin breakdown from the oxygen delivery device.
The patient’s ABG or SpO₂ values return to normal or baseline.

UNEXPECTED OUTCOMES

The patient experiences continued hypoxemia or increased work of breathing.
The patient experiences drying of nasal and upper airway mucosa.
The patient’s vital signs become unstable.
The patient repeatedly removes the oxygen delivery device.
The oxygen delivery device is improperly fitting or uncomfortable.
The patient experiences facial irritation and skin breakdown.

DOCUMENTATION

Education
Respiratory assessment
Method of oxygen delivery and flow rate
Vital signs and SpO₂ level
Unexpected outcomes and related interventions
Patient’s tolerance of oxygen therapy and device

PEDIATRIC CONSIDERATIONS

Some infants and small children are able to tolerate a nasal cannula. Secure the prongs with tape or strips of transparent dressing over the child’s cheek.
Typically, infants receive oxygen therapy via an oxygen hood or tent. Place the hood over the infant’s head (sometimes including the shoulders of a small infant); allow enough room between the curve of the hood and the infant’s neck to allow carbon dioxide to escape. Place the oxygen tent over the infant’s upper body and rest it on the bed or bed rails.
Inspect toys placed in the tent for safety and suitability. Any source of sparks (e.g., from mechanical or electrical toys) is a potential fire hazard.
The presence of family members provides comfort and reassurance to the child and helps decrease anxiety and labored breathing.

OLDER ADULT CONSIDERATIONS

Because older adults have fragile skin and mucous membranes, offer them oral hygiene and skin care more frequently.
Check the skin frequently for signs of irritation or breakdown. Padding the skin may be necessary to prevent pressure injuries.

HOME CARE CONSIDERATIONS

Consult with the practitioner regarding a home care consult and the need for home oxygen therapy equipment.
Explain how to use the oxygen delivery device, how to contact the supplier of medical equipment, and when to contact the practitioner.
Teach the patient and family the importance of and rationale for oxygen therapy as well as the safety precautions for oxygen use.
- Explain to the patient that oxygen increases the risk of combustion and that activities that increase the risk of a fire (such as smoking or open flames) or activities that could create sparks are not allowed.
- Explain to the patient that all electrical equipment must be properly grounded to prevent electrical sparks, which can lead to a serious fire.
Ensure that the patient has oxygen tanks or an oxygen concentrator at home.
Encourage the patient to drink plenty of fluids to help prevent drying of the mucosa unless contraindicated.

REFERENCES

Heuer, A.J., Hilse, A.M. (2021). Chapter 42: Medical gas therapy. In R.M. Kacmarek, J.K. Stoller, A.J. Heuer (Eds.), Egan’s fundamentals of respiratory care (12th ed., pp. 906-935). St. Louis: Elsevier.
Piraino, T. and others. (2022). AARC (American Association for Respiratory Care) clinical practice guideline: Management of adult patients with oxygen in the acute care setting. Respiratory Care, 67(1), 115-128. doi:10.4187/respcare.09294 (Level VII)
Rochwerg, B. and others. (2019). High flow nasal cannula compared with conventional oxygen therapy for acute hypoxemic respiratory failure: A systematic review and meta-analysis. Intensive Care Medicine, 45(5), 563-572. doi:10.1007/s00134-019-05590-5 (Level I)

Adapted from Perry, A.G. and others (Eds.). (2022). Clinical nursing skills and techniques (10th ed.). St. Louis: Elsevier.

Elsevier Skills Levels of Evidence

Level I - Systematic review of all relevant randomized controlled trials
Level II - At least one well-designed randomized controlled trial
Level III - Well-designed controlled trials without randomization
Level IV - Well-designed case-controlled or cohort studies
Level V - Descriptive or qualitative studies
Level VI - Single descriptive or qualitative study
Level VII - Authority opinion or expert committee reports

Clinical Review: Ashley Hinman, MSN, RN

Published: February 2024