Oxygen therapy is a lifesaving intervention in patients with hypoxemia (low blood oxygen levels). Understanding the signs of hypoxia and how to select the right oxygen delivery device can make the difference between rapid recovery and respiratory failure.
This guide provides a complete breakdown of hypoxia recognition, oxygen delivery methods, and advanced airway interventions — ideal for nurses, medical students, and healthcare providers.
Understanding Hypoxia and Hypoxemia
- Hypoxia: Low oxygen supply to the tissues.
- Hypoxemia: Low oxygen levels in the blood (PaO₂ < 80 mmHg).
Early Signs of Hypoxemia
Brain: Mental status changes – restlessness, irritability, confusion
Vital Signs:
- Tachypnea (RR > 20)
- Tachycardia (HR > 100 bpm)
- Hypertension (BP > 140 systolic)
Late Signs of Hypoxemia
- Low vitals: bradypnea (<12), bradycardia (<60), hypotension
- Cyanosis (bluish skin)
- ECG dysrhythmias
Oxygen Safety Precautions
- Avoid combustion – oxygen is highly flammable
- No smoking or open flames near oxygen sources
- Avoid static-producing fabrics (use cotton)
- Keep away from flammable materials like alcohol-based gels
Oxygen Delivery Devices – Detailed Guide
| Device | Flow Rate | FiO₂ Range | Key Points |
|---|---|---|---|
| Nasal Cannula (NC) | 1–6 L/min | 25–45% | Low oxygen needs; post-surgery recovery; humidification for long-term use |
| Simple Face Mask | 6–10 L/min | 40–60% | Short-term use; higher FiO₂ than NC |
| Partial Rebreather Mask | 6–10 L/min | 35–60% | Similar to non-rebreather but with flutter valves |
| Non-Rebreather Mask (NRB) | 10–15 L/min | 60–100% | Medical emergencies; carbon monoxide poisoning; ensure reservoir bag inflation |
| Venturi Mask | 4–10 L/min | Precise FiO₂ | Best for COPD patients; allows controlled O₂ delivery |
| Face Tent | Variable | High humidification | For facial trauma/burns where masks are uncomfortable |
Specialized Oxygen Therapies
1. BiPAP (Bilevel Positive Airway Pressure)
- Indication: Worsening COPD with high CO₂ retention (hypercapnia > 45 mmHg)
- Mechanism: Provides higher pressure on inhalation and lower on exhalation
- Improves oxygenation while removing CO₂
- Often used before intubation in respiratory failure
Memory Trick: HyperCAP → Give BiPAP
2. Endotracheal Intubation
Indication: Severe respiratory failure, unprotected airway
Tube inserted into trachea for mechanical ventilation
- Prevent by repositioning Q2H, oral care with chlorhexidine Q2H
- Monitor for fever, positive sputum culture, new infiltrates on chest X-ray
Choosing the Right Device – Clinical Approach
- Mild hypoxemia: Start with Nasal Cannula
- Moderate hypoxemia: Simple mask or Venturi mask (especially for COPD)
- Severe hypoxemia/emergency: Non-rebreather mask
- CO₂ retention: Consider BiPAP
- Impending respiratory arrest: Intubation
Quick Reference – Hypoxia Management Table
| Severity | Device Choice | Flow Rate | Notes |
|---|---|---|---|
| Mild | NC | 1–6 L/min | Comfortable, low O₂ delivery |
| Moderate | Simple Mask / Venturi | 4–10 L/min | Venturi for COPD |
| Severe | NRB | 10–15 L/min | 100% O₂ possible |
| CO₂ Retention | BiPAP | N/A | High CO₂ clearance |
| Arrest Risk | Intubation | Mechanical Vent | Definitive airway |
Frequently Asked Questions (FAQs)
1. Why not start all patients on 100% oxygen?
High oxygen concentrations can cause CO₂ retention in COPD patients and oxygen toxicity in prolonged use.
2. How can you tell if a non-rebreather mask is working?
The reservoir bag should remain partially inflated during inspiration.
3. Why is the Venturi mask preferred in COPD?
It delivers a precise FiO₂, preventing suppression of hypoxic drive.
4. Can oxygen therapy be harmful?
Yes, in certain conditions like COPD, excess oxygen can worsen hypercapnia.
5. Is humidification always required?
Only for high-flow oxygen or long-term NC use to prevent mucosal dryness.
