Acute Hypoxemic Respiratory Failure
Hypoxia despite conventional O2 therapy
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Pulmonary MedicineManagement
High-Flow Nasal Cannula (HFNC) Therapy
High-Flow Nasal Cannula (HFNC) Therapy: Acute Hypoxemic Respiratory Failure → HFNC Indicated? → ⚠️ Consider NIV/Intubation Instead → Intubation.
Pathway Overview
14 steps
Algorithm Steps
14 total
01Start 02Decision HFNC Indicated?
Assess suitability
- INDICATIONS:
- • Hypoxemia despite O2 15L/min NRB
- • Type 1 respiratory failure
- • Post-extubation support
- • Immunocompromised with ARF
- • Pre-oxygenation for intubation
- • Palliative comfort
03Warning ⚠️ Consider NIV/Intubation Instead
HFNC may not be appropriate
- Hypercapnic respiratory failure (Type 2)
- Severe acidosis (pH <7.25)
- Hemodynamic instability
- Decreased consciousness (GCS <12)
- Unable to protect airway
- Facial trauma/surgery
04Outcome Intubation
HFNC failure
- Do not delay intubation if failing
- HFNC can be used during apneic oxygenation
- Experienced intubator preferred
- Video laryngoscopy recommended
05Action Initiate HFNC
Starting settings
- Flow: Start at 30-40 L/min
- FiO2: Start at 0.6-1.0 (titrate to SpO2)
- Temperature: 37°C (or 34°C if not tolerated)
- Nasal prongs sized appropriately
- Ensure proper humidification
06Action Titrate Settings
Optimize flow and FiO2
- FLOW: Increase to 50-60 L/min if needed
- Higher flow = more PEEP effect, CO2 washout
- FiO2: Titrate to SpO2 92-96% (88-92% if COPD)
- Reduce flow if discomfort/nasal dryness
07Action Close Monitoring
Assess response hourly
- Respiratory rate (target <25-30/min)
- SpO2 on current settings
- Work of breathing
- Patient comfort
- ROX index at 2, 6, 12 hours
08Decision Calculate ROX Index
Predict HFNC success/failure
- ROX = (SpO2/FiO2) / Respiratory Rate
- At 2h: ROX ≥4.88 = likely success
- At 6h: ROX ≥4.88 = likely success
- At 12h: ROX <3.85 = likely failure
- Lower ROX = higher intubation risk
09Action ROX ≥4.88 (Favorable)
Continue HFNC
- Low intubation risk
- Continue current settings
- Wean FiO2 if SpO2 above target
- Can consider flow reduction later
10Action Weaning HFNC
When improving
- Reduce FiO2 first (to 0.4 or less)
- Then reduce flow (by 5-10 L/min steps)
- Monitor for rebound hypoxemia
- Consider trial on nasal cannula
11Outcome Transition to Conventional O2
Weaning successful
- If SpO2 maintained on low-flow HFNC
- Trial simple nasal cannula or mask
- Monitor closely after transition
- Can return to HFNC if needed
12Action ROX 3.85-4.88 (Intermediate)
Heightened vigilance
- Increase monitoring frequency
- Optimize settings
- Prepare for escalation if declining
- Repeat ROX in 2 hours
- Path rejoins step 08Shared downstream outcome
13Decision Clinical Deterioration?
Signs of HFNC failure
- Worsening hypoxemia despite max settings
- RR increasing >35-40/min
- Accessory muscle use worsening
- Hemodynamic instability
- Altered mental status
- Path rejoins step 04Shared downstream outcome
- Path rejoins step 07Shared downstream outcome
14Warning ⚠️ ROX <3.85 (Unfavorable)
High failure risk
- Consider early intubation
- Do not delay if deteriorating
- Trial of NIV may be considered
- Avoid prolonged HFNC failure
- Path rejoins step 13Shared downstream outcome
Guideline Source
High-Flow Nasal Cannula Oxygen Therapy: Evidence and Practice
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Settings require individual titration
- Not a substitute for invasive ventilation in severe cases
- Patient tolerance varies
- Humidification settings depend on device
Applicable Regions
Global
Global: Device availability and protocols vary by institution
Version 1Next review: 2027-01-01
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Related Resources
Frequently Asked Questions
What is the High-Flow Nasal Cannula (HFNC) Therapy?
The High-Flow Nasal Cannula (HFNC) Therapy is a management clinical algorithm for Pulmonary Medicine. It provides a structured decision tree to guide clinical decision-making, based on High-Flow Nasal Cannula Oxygen Therapy: Evidence and Practice.
What guideline is the High-Flow Nasal Cannula (HFNC) Therapy based on?
This algorithm is based on High-Flow Nasal Cannula Oxygen Therapy: Evidence and Practice (DOI: 10.1164/rccm.202205-0901OC).
What are the limitations of the High-Flow Nasal Cannula (HFNC) Therapy?
Known limitations include: Settings require individual titration; Not a substitute for invasive ventilation in severe cases; Patient tolerance varies; Humidification settings depend on device. Individual patient factors may require deviation from these recommendations.
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