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

The content in Clinical Skills is evidence based and intended to be a guide to clinical practice. Always follow your organization’s practice.

ALERT

Oxygen is considered a medication and requires a practitioner’s order; administer it cautiously and observe the patient closely for adverse reactions.

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. Signs and symptoms of hypoxia include restlessness, anxiety, disorientation, confusion, and fatigue (Box 1).

Two types of oxygen delivery systems are high flow and low flow. Selection of the type of oxygen therapy is based on the patient’s need, the severity of hypoxemia, and the disease process. A prescription is required for oxygen therapy. The prescription should include the oxygen-delivery device, the flow rate, and the amount of oxygen to deliver.²

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 85% to 92%.¹

Low-Flow Oxygen Therapy

Devices that deliver low-flow oxygen therapy include a nasal cannula, various types of face masks, and oxygen tents and hoods (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.

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 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

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.³ 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 high 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. This is particularly useful in children with airway inflammation, epiglottitis (croup), or other respiratory tract infections. 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

High-flow systems decrease the entraining of room air, which can dilute the fraction of inspired oxygen (FIO₂).

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 a specialized nasal cannula (Figure 6). Conventional nasal cannula devices can deliver flows of only 1 to 6 L/min, whereas high-flow nasal cannula (HFNC) therapy delivers flows up to 60 L/min.¹

HFNC therapy can be used to treat a new onset respiratory failure as well as exacerbations of chronic pulmonary disease. There is early evidence indicating that there is less need for invasive ventilation in patients who are initially treated with HFNC therapy.² HFNC 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

• Give developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, preferred learning style, and overall neurologic and psychosocial state.
• Provide the patient and family with an explanation of the equipment and the procedure.
• If the patient is going home on oxygen, the nurse should review the safety precautions for oxygen use and ensure that a referral for home oxygen is in place so that the patient has continuity of care and a decreased risk of hypoxia.
• 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

1. Determine if the patient has health literacy needs or requires tools or assistance to effectively communicate. Be sure these needs can be met without compromising safety.
2. Review the patient’s previous experience and knowledge of oxygen therapy and understanding of the care to be provided.
3. Assess the patient’s respiratory status, including the symmetry of chest wall expansion, respiratory rate and depth, sputum production, and breath sounds.
4. Assess the patient for signs and symptoms of hypoxia (Box 1).
5. Observe the patient for behavioral changes (e.g., apprehension, anxiety), decreased level of consciousness (LOC), or light-headedness.
6. Assess the patient’s airway patency. If secretions are present, encourage the patient to cough or suction the airway.
7. Evaluate the patient’s vital signs and the SpO₂ value.
8. Evaluate the patient’s most recent arterial blood gas (ABG) results, if available.
9. Inspect the condition of the patient’s skin around the nose and ears.

Preparation

1. Verify the order for oxygen therapy, noting the delivery method and flow rate.
2. Check that all electrical equipment in the patient room is functioning correctly and properly grounded. An electrical spark in the presence of oxygen can result in a fire.²

   Avoid using items that create a spark in the patient room (e.g., electric razor) with a nasal cannula in use.

PROCEDURE

Oxygen Therapy

1. 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 greater than 4 L/min.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.
2. Adjust the oxygen flowmeter to the prescribed flow rate (Figure 7).
3. 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 downward² (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.

4. 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.

HFNC Oxygen Therapy

1. Position the nasal cannula on the patient’s face and adjust the head strap to achieve a comfortably snug fit (Figure 6). Follow the manufacturer’s instructions for application.
2. Ensure proper positioning of the cannula tips in the patient’s nares. If the cannula tips are curved, ensure that they point downward.² Maintain enough slack on the oxygen tubing.
3. Review the high-flow oxygen delivery device settings, use of humidifier and heater, and alarms with the respiratory therapist.
4. 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.

MONITORING AND CARE

1. Observe the oxygen delivery device frequently to ensure proper placement. Readjust as necessary.
2. 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.⁴

3. Consider adding continuous SpO₂ monitoring for patients newly placed on oxygen.²
4. 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.
5. 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 hypoxia 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 signs of hypoxia.
• 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.

REFERENCES

1. Heuer, A.J., Lombardo, G. (2025). Chapter 42: Medical gas therapy. In J.K. Stoller and others (Eds.), Egan’s fundamentals of respiratory care (13th ed., pp. 900-929). St. Louis: Elsevier.
2. Perry, A.G. (2025). Chapter 23: Oxygen therapy. In A.G. Perry and others (Eds.), Clinical nursing skills & techniques (11th ed., pp. 718-752). St. Louis: Elsevier.
3. Piraino, T. and others. (2022). AARC 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
4. 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

Adapted from Perry, A.G. and others (Eds.). (2025). Clinical nursing skills & techniques (11th ed.). St. Louis: Elsevier.

Clinical Review: Genevieve L. Hackney, MSN, RN

Published: January 2025