Guidelines for Initiating and Managing Oxygen Therapy
Oxygen therapy should be initiated with an initial FiO2 of 0.6 (60%) and then titrated to specific target oxygen saturation ranges based on the patient's underlying condition, with SpO2 of 88-92% for COPD patients and those at risk of hypercapnic respiratory failure, and SpO2 of 94-98% for most other patients. 1
Initial Assessment and Device Selection
When initiating oxygen therapy, the appropriate device and flow rate should be selected based on the severity of hypoxemia:
| Severity | Device | Initial Flow Rate | Target SpO₂ |
|---|---|---|---|
| Mild hypoxemia | Nasal cannulae | 1-2 L/min | 94-98% |
| Moderate hypoxemia | Simple face mask | 5-6 L/min | 94-98% |
| COPD/hypercapnic risk | Venturi mask 24-28% | 2-6 L/min | 88-92% |
| Severe hypoxemia | Reservoir mask | 15 L/min | 94-98% |
Target Oxygen Saturation by Patient Population
- General patients: SpO2 of 94-98% 1
- COPD and risk of hypercapnic failure: SpO2 of 88-92% 1
- Pregnant patients and children with emergency signs: SpO2 >94% 1
- Pediatric patients: SpO2 above 90% and no higher than 96% (Australian guidelines recommend minimum SpO2 of 92%) 1
Escalation Protocol
Oxygen therapy should be escalated based on clinical response:
| Device | Initial Flow | Escalation |
|---|---|---|
| Nasal Cannulas | 1-2 L/min | Increase up to 6 L/min |
| Simple Mask | 5 L/min | Increase up to 10 L/min |
| Venturi Mask 24% | 2-3 L/min | Switch to 28% (4-6 L/min) |
| Reservoir Mask | 15 L/min | Maintain and seek specialized help |
Special Considerations for COPD Patients
- Critical caution: Avoid excessive oxygen in patients with COPD or other risk factors for hypercapnic respiratory failure 1
- Patients with baseline hypercapnia are at particular risk for worsening CO2 retention when oxygen is increased without adjusting flow rates 2
- Research shows that COPD patients with baseline hypercapnia experienced significant increases in PaCO2 when FiO2 was increased by 30% without changing flow rate 2
High-Flow Nasal Cannula Oxygen Therapy (HFNCO)
HFNCO can deliver oxygen flow rates up to 60 L/min and has several advantages over conventional oxygen therapy:
- Delivers precise FiO2 even with high inspiratory flow demands 3
- Provides adequate humidification and warming of inspired gas 3
- May reduce work of breathing 4
- Can be used for preoxygenation before intubation and after extubation to prevent reintubation 4
HFNCO has shown promising results in:
- Hypoxemic acute respiratory failure 3
- Supporting patients during bronchoscopy 3
- Post-extubation support 3
- Acute exacerbation of idiopathic pulmonary fibrosis, where it reduced short-term mortality below 50% 5
Monitoring Requirements
- Record oxygen saturation before starting therapy 1
- Document target saturation range on observation chart 1
- Record new saturation and delivery system after any change 1
- Require sign-off for each change in oxygen therapy 1
- Monitor for signs of respiratory deterioration:
- Increased respiratory rate
- Use of accessory muscles
- Paradoxical breathing
- Rising NEWS or Track and Trigger score 1
- Use capnography, transcutaneous CO2 measurement, or arterial blood gas analysis to monitor carbon dioxide levels 1
- Maintain continuous oxygen saturation monitoring for at least 24 hours 1
Common Pitfalls and Caveats
Ignoring patient complaints: Agitation or complaints of difficulty breathing should never be ignored, even if objective signs like oxygen saturation are normal 1
Inappropriate oxygen targets for COPD: Using standard oxygen targets (94-98%) in COPD patients can lead to dangerous hypercapnia and respiratory acidosis 1, 2
Inadequate assessment: Many patients using home oxygen have not been properly assessed by respiratory specialists, potentially missing those who would benefit from long-term oxygen therapy 6
Lack of monitoring: Patients on HFNC are critically ill and require continuous monitoring with capability for therapy escalation at any time 4
Delayed escalation: Failure to recognize when a patient requires escalation to non-invasive or invasive ventilation can lead to worse outcomes 1