Starting Order for High-Flow Oxygen Therapy
For patients requiring high-flow oxygen therapy, start with a flow rate of 60 L/min and FiO2 of 0.6 (60%), then titrate based on SpO2 response and clinical parameters. 1
Initial Flow Rate Selection
Begin with 60 L/min as the starting flow rate for high-flow nasal oxygen (HFNO) therapy, as this provides superior outcomes compared to lower initial flows. 1
- In cardiac surgery patients with hypoxemia, an initial flow of 60 L/min resulted in 2.4-3.9 times higher probability of achieving SpO2 >92% and respiratory rate 12-20 breaths/min compared to 40 L/min or conventional oxygen. 1
- The 60 L/min starting flow demonstrated lower hazard for treatment failure (HR 0.11) compared to conventional oxygen therapy. 1
- While 40 L/min also showed benefit over conventional therapy (HR 0.30), the 60 L/min flow was superior for achieving target oxygenation and respiratory rate parameters. 1
Initial FiO2 Setting
Set initial FiO2 at 0.6 (60%) as the standard starting point, which can then be titrated to achieve target saturations. 1
- This starting FiO2 allows room for both upward and downward titration based on patient response. 1
- The British Thoracic Society guidelines support high-flow oxygen as an alternative to reservoir mask treatment in acute respiratory failure without hypercapnia. 2
Target Saturation Ranges
Target SpO2 94-98% for most patients without risk of hypercapnic respiratory failure. 2
Target SpO2 88-92% for patients with COPD or other risk factors for hypercapnic respiratory failure (morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders, fixed airflow obstruction with bronchiectasis). 2
Titration Protocol
Allow at least 5 minutes at each setting before making further adjustments, except when saturation falls suddenly by ≥3%. 2
- Monitor SpO2, respiratory rate, heart rate, blood pressure, and mental status continuously during initiation. 3
- Adjust FiO2 first to achieve target saturation, maintaining flow rate at 60 L/min initially. 1
- If target saturation cannot be achieved at FiO2 1.0 (100%) and 60 L/min, seek senior medical input immediately and consider escalation to non-invasive ventilation or intubation. 2
Critical Monitoring Parameters
Respiratory rate >30 breaths/min requires immediate intervention even if SpO2 appears adequate, as this indicates respiratory distress. 3
- Obtain arterial blood gases within 1 hour if increased oxygen requirements develop. 2
- Reassess blood gases after 30-60 minutes in patients at risk for hypercapnic respiratory failure. 2
- A sudden fall in SpO2 of ≥3% requires clinical reassessment even if saturation remains within target range. 2
Important Caveats
High-flow oxygen does not guarantee accurate FiO2 delivery when patient inspiratory flow exceeds device flow. 4
- At peak inspiratory flows of 60-120 L/min (common in acute respiratory failure), the actual inspired FiO2 may be significantly lower than the set FiO2. 4
- This variability is most pronounced when patient inspiratory flow exceeds the set device flow, emphasizing the importance of starting at 60 L/min rather than lower flows. 4
Patients on high-flow oxygen are critically ill and require continuous monitoring with capability for immediate escalation to invasive ventilation. 5
When NOT to Use High-Flow Oxygen
Avoid high-flow oxygen as first-line therapy in hypercapnic respiratory failure with respiratory acidosis—use non-invasive ventilation instead. 5, 6
- In acute-on-chronic respiratory failure with acidosis, NIV is clearly superior. 6
- High-flow oxygen data in hypercapnic failure are inconclusive and NIV should be preferred. 5
Weaning Considerations
Reduce FiO2 first while maintaining flow rate if patient is stable and SpO2 is in the upper target range for 4-8 hours. 3