RN Nursing · Physiological Integrity
Oxygen Therapy Basics: Delivery Devices, Safety, and Nursing Considerations
By Nurse Jude
·
Updated June 19, 2026
A clear, exam-focused review of supplemental oxygen therapy, covering delivery devices, FiO2 ranges, device selection by clinical scenario, complications, and safety precautions.
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Oxygen therapy is one of the most common nursing interventions, but choosing the right device, flow rate, and safety precautions is critical to prevent complications such as oxygen toxicity, CO2 retention, or fire hazards. This note reviews the essential devices, indications, and exam-focused considerations.
Definition and Goal
- Oxygen therapy is the administration of supplemental oxygen to treat or prevent hypoxemia.
- Typically prescribed when SpO2 is below the target range (usually <90–92%).
- The goal is to maintain adequate tissue oxygenation without causing oxygen toxicity or CO2 retention.
Oxygen Delivery Devices
| Device | Flow Rate | FiO2 Delivered | Key Points |
|---|---|---|---|
| Nasal cannula | 1–6 L/min | 24–44% | Most common; humidify if >4 L/min |
| Simple face mask | 6–12 L/min | 35–50% | Flow must be ≥6 L/min to flush CO2 |
| Partial rebreather mask | 6–10 L/min | 40–70% | Reservoir bag must stay inflated |
| Non-rebreather mask | 10–15 L/min | 80–95% | Highest FiO2 without intubation |
| Venturi mask | 4–12 L/min | 24–50% | Most precise; preferred for COPD |
| Face tent | 8–12 L/min | 28–100% | For facial trauma or burns |
Device-specific notes
- Nasal cannula: Allows eating and talking. Each L/min increases FiO2 by approximately 4%. Check nares patency before applying; humidify if flow exceeds 4 L/min to prevent mucosal drying.
- Simple face mask: Requires ≥6 L/min to flush exhaled CO2 from the mask.
- Non-rebreather mask: Delivers the highest FiO2 without invasive ventilation. The reservoir bag must remain fully inflated at all times; a loose seal allows room air to dilute oxygen.
- Venturi mask: Delivers a precise FiO2 regardless of the patient's respiratory pattern. Color-coded adapters correspond to specific FiO2 settings. Device of choice for COPD.
Device Selection by Clinical Scenario
| Scenario | Recommended Device | Rationale |
|---|---|---|
| Mild hypoxemia (SpO2 90–94%) | Nasal cannula 1–4 L/min | Comfortable, allows eating |
| Moderate hypoxemia (SpO2 85–90%) | Simple mask or nasal cannula up to 6 L/min | Higher FiO2 |
| Severe hypoxemia (SpO2 <85%) | Non-rebreather mask | Highest FiO2 without intubation |
| COPD with CO2 retention | Venturi mask | Precise FiO2; prevents hypercapnia |
| Facial trauma or burns | Face tent | Avoids contact with injured skin |
- For severe hypoxemia, apply a non-rebreather mask immediately. If the patient does not improve, prepare for endotracheal intubation.
- For COPD patients, the Venturi mask is preferred because uncontrolled high-flow oxygen may suppress the hypoxic drive.
Safety Precautions
- Oxygen is combustible. Post "No Smoking" signs and keep oxygen away from open flames and heat sources.
- Do not use petroleum-based products (e.g., Vaseline, oil-based lotions) — they create a fire hazard. Use water-based lubricants instead.
- Do not store oxygen cylinders in enclosed spaces (closets) or near curtains. Secure cylinders upright in approved racks.
Complications of Oxygen Therapy
| Complication | Cause | Prevention |
|---|---|---|
| Oxygen toxicity | High FiO2 for >24–48 hours | Use lowest effective FiO2 |
| Absorption atelectasis | High FiO2 displaces nitrogen | Use lowest effective FiO2 |
| CO2 retention (COPD) | Loss of hypoxic drive | Use Venturi mask; monitor ABGs |
| Nasal mucosal dryness | Unhumidified oxygen | Humidify if flow >4 L/min |
- Oxygen toxicity causes structural lung damage when FiO2 >60% is administered for more than 24–48 hours.
- CO2 retention occurs when high-flow oxygen suppresses the respiratory drive in sensitive COPD patients. Monitor for drowsiness, headache, and elevated CO2 levels.
Assessing Effectiveness
- Monitor SpO2 continuously or at regular intervals to maintain the target range.
- Assess respiratory rate, depth, and effort, plus mental status — new confusion is an early sign of hypoxia or hypercapnia.
- Document signs of improvement: resolution of cyanosis, decreased work of breathing, improved level of consciousness.
Common Exam Traps
- Do not set simple face mask flow <6 L/min (causes CO2 rebreathing).
- Do not let the non-rebreather reservoir bag deflate on inspiration — increase the flow rate.
- Do not give high-flow oxygen to a COPD patient without close monitoring for respiratory depression.
- Do not apply oil-based products to lips or nares during oxygen therapy.
- Do not omit humidification when nasal cannula flow >4 L/min.
- Do not leave oxygen cylinders unsecured or near heat sources.
Key takeaways
- Nasal cannula (1–6 L/min) is comfortable and allows eating/talking but requires humidification above 4 L/min.
- Non-rebreather mask (10–15 L/min) delivers the highest FiO2 (80–95%) without intubation; keep the reservoir bag inflated.
- Venturi mask provides the most precise FiO2 and is the safest choice for COPD patients at risk of CO2 retention.
- Simple face mask requires a minimum of 6 L/min to prevent CO2 rebreathing.
- Prevent fires: no petroleum products, no open flames, secure cylinders upright.
- Titrate to the lowest effective FiO2 while monitoring SpO2, work of breathing, and mental status.
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