What is the recommended initial Fraction of Inspired Oxygen (Fio2) level for patients requiring supplemental oxygen?

Initial FiO2 Recommendations for Supplemental Oxygen Therapy

For patients requiring supplemental oxygen therapy, the initial FiO2 should be 0.6 (60%) for patients requiring CPAP or non-invasive ventilation, while patients with mild hypoxemia should start with nasal cannula at 1-2 L/min targeting SpO2 94-98%. 1

Initial FiO2 Settings Based on Clinical Scenario

The appropriate initial FiO2 depends on the severity of hypoxemia and the oxygen delivery device being used:

For Non-Invasive Ventilation/CPAP:

• Initial FiO2: 0.6 (60%) 2, 1
• If further escalation needed, FiO2 can be increased to 0.6-1.0 (60-100%) 2
• For patients with lower oxygen requirements (FiO2 < 0.4 or 40%), low-flow CPAP may be suitable 2

For Conventional Oxygen Therapy:

• Mild hypoxemia: Nasal cannula at 1-2 L/min (target SpO2 94-98%) 1
• Moderate hypoxemia: Simple face mask at 5-6 L/min (target SpO2 94-98%) 1
• Severe hypoxemia: Reservoir mask at 15 L/min (target SpO2 94-98%) 1

Special Populations:

• COPD or hypercapnic risk: Venturi mask 24-28% at 2-6 L/min (target SpO2 88-92%) 1
• Pregnant patients: Target SpO2 >94% 2
• Children with emergency signs: Target SpO2 >94% 2

Target Oxygen Saturation Goals

The target SpO2 varies based on patient characteristics:

• General population: 94-98% 1
• COPD or risk of hypercapnic respiratory failure: 88-92% 2, 1
• Strong respiratory drive with normal/low PaCO2: Target SpO2 94% 2
• Type 2 respiratory failure (acute or chronic): Target SpO2 88-92% 2
• Pediatric patients: SpO2 should be above 90% and no higher than 96% 2
• Australian guidelines for pediatrics: Maintain SpO2 of at least 92% 2

Monitoring and Titration

Proper monitoring is essential when initiating oxygen therapy:

• Monitor oxygen saturation continuously for at least 24 hours 1
• Evaluate patients within 1-2 hours after initiating NIV to assess response 2
• Document target saturation range on observation chart 1
• Record new saturation and delivery system after any change 1
• Consider transcutaneous CO2 measurement or arterial blood gas analysis to monitor carbon dioxide levels 1

Important Considerations and Pitfalls

Racial Differences in Oximetry Readings

• In Black patients, a SpO2 target of 95% may be required to ensure adequate oxygenation, compared to 92% in White patients 3
• Inaccurate oximetry readings (>4% difference between SpO2 and direct SaO2) are more common in Black patients (27%) than in White patients (11%) 3

Risks of Hyperoxia

• Excessive oxygen can worsen hypercapnia, especially in patients with COPD 1
• Some evidence suggests potential harm from higher fractions of inspired oxygen compared to lower fractions, including increased mortality and serious adverse events 4
• Liberal oxygen administration should be avoided when not indicated 5

Escalation Protocol

If the patient doesn't respond to initial oxygen therapy:

1. Increase flow rates within the current device's capabilities
2. Switch to a higher-flow delivery system
3. Consider non-invasive ventilation if respiratory distress persists
4. Monitor for signs of respiratory deterioration requiring ICU admission 1

Conclusion

When initiating supplemental oxygen therapy, start with FiO2 of 0.6 (60%) for patients requiring CPAP/NIV and titrate based on response. For conventional oxygen therapy, match the delivery device and flow rate to the severity of hypoxemia. Always consider the patient's underlying condition when setting target SpO2 values, with special attention to those at risk for hypercapnic respiratory failure.