A COPD patient on 2L NC has SpO2 95% but is becoming drowsy. What should the nurse do?
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Pathophysiology · ELI Explains: Respiratory Pathophysiology (book 3)
Oxygen Delivery Devices
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The college version
Clinical Orientation
A nurse must choose the right oxygen delivery device: nasal cannula, simple mask, non-rebreather, Venturi mask, high-flow nasal cannula, or noninvasive ventilation. Each device has specific capabilities, limitations, and nursing considerations. This chapter answers: How do you match the device to the patient's needs and monitor safely?
Device Comparison
| Device | Flow Rate | Approximate FiO2 | Best For | Limitations |
|---|---|---|---|---|
| Nasal cannula | 1-6 L/min | 24-44% | Mild hypoxemia, chronic O2 | FiO2 varies with RR and mouth breathing. Dries mucosa >4L. |
| Simple face mask | 5-10 L/min | 35-55% | Moderate hypoxemia | Minimum 5L to flush CO2. Claustrophobia. |
| Non-rebreather | 10-15 L/min | 60-95% | Severe hypoxemia, emergencies | Reservoir bag must remain partially inflated. Valves prevent rebreathing. |
| Venturi mask | Variable | 24-50% (precise) | COPD, precise FiO2 needed | Color-coded adapters. High flow entrains room air for precise concentration. |
| High-flow nasal cannula (HFNC) | Up to 60 L/min | 21-100% | Moderate-severe hypoxemia | Heated, humidified. Provides some PEEP. Comfortable for prolonged use. |
| CPAP | N/A | 21-100% | Cardiogenic pulmonary edema, sleep apnea | Continuous positive pressure — keeps alveoli open. |
| BiPAP | N/A | 21-100% | COPD exacerbation, hypercapnic respiratory failure | IPAP + EPAP. Reduces work of breathing. |
Nursing Priorities
- Oxygen is a medication. It requires an order. Titrate to target SpO2 — not to a flow rate.
- Too much oxygen can harm: COPD retainers (suppress hypoxic drive, absorption atelectasis), post-cardiac arrest (hyperoxia worsens neurologic outcomes), MI (possible vasoconstriction).
- Humidification: For flows >4 L/min via nasal cannula, or any prolonged use.
- Skin integrity: Nasal cannula behind ears, face masks on bridge of nose — check and pad.
- Escalate early: If a non-rebreather isn't maintaining SpO2 >90%, the patient needs CPAP/BiPAP or intubation — not just more oxygen.
Key takeaways
- Answer: B. In a CO2 retainer, SpO2 above target + drowsiness = possible oxygen-induced hypercapnia. Reduce O2 to bring SpO2 into target range while the provider is notified for an ABG.
- Oxygen is a medication — prescribe and titrate.
- Nasal cannula: 1-6L, simple face mask: 5-10L, non-rebreather: 10-15L.
- COPD target: 88-92%. Most others: ≥94%.
- Escalate device early — don't wait for desaturation to change the plan.
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Check yourself
1 review question from the chapter. Try each one, then open the answer.
A COPD patient on 2L NC has SpO2 95% but is becoming drowsy. What should the nurse do?
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Increase O2 to maintain SpO2 B. Decrease O2 — SpO2 95% exceeds the target of 88-92%, and the patient may be developing CO2 retention from excessive oxygen C. Switch to non-rebreather D. Administer naloxone
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