FFS: Nasal High Flow Oxygen (NHF)

These systems are particularly useful for:

• Prolonged oxygen therapy in respiratory distress
• Ward-based care where NIV is unavailable or inappropriate
• Avoiding ICU admission or palliative withdrawal of therapy in unsuitable ICU candidates

NHF enables sustained oxygenation in patients who cannot tolerate or don’t require NIV, and can be safely managed in ward settings.

Indications

NHF is useful across a range of respiratory conditions:

• General hypoxia
• Post-extubation support
• Mild COPD or asthma exacerbations
• Pneumonia
• Bronchiectasis
• Mild acute pulmonary oedema
• Chest trauma or post-op respiratory distress
• Tracheostomy/laryngectomy support
• Hypothermia (warm gas delivery)
• Palliative/oncology patients

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Advantages

1. High flow rates (up to 45 L/min) allow:
   • Better FiO₂ delivery in dyspnoeic patients with high inspiratory demand
   • Clearance of nasopharyngeal dead space
   • Limited positive airway pressure at higher flow rates
2. Ward-manageable:
   • Avoids prolonged ED/HDU/ICU stay
   • Requires less intensive nursing compared to NIV
3. Patient comfort:
   • No tight-fitting mask
   • Able to speak and eat
   • No sensation of claustrophobia
4. Humidified, warmed oxygen:
   • Improves secretion clearance (esp. in COPD)
   • Reduces airway irritation
   • Supports hypothermia management

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Disadvantages

• Cannot deliver 100% FiO₂
• Does not provide ventilatory support
• Less effective in:
  • Severe hypoxia
  • CO₂ retention
  • Patients with increased work of breathing or exhaustion

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Contraindications

• Complete nasal obstruction
• Maxillofacial trauma or base of skull fracture
• Post-nasal surgery
• Raised intracranial pressure
• Persistent epistaxis

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Management Principles

Use NHF for:

• Mild to moderate respiratory distress
• Patients requiring prolonged oxygen therapy
• Step-down from NIV
• Ward-based palliation where Hudson mask is inadequate

In severe COPD, asthma, or APO — NHF is not a substitute for NIV or intubation, but may be:

• A bridge during recovery
• A comfort therapy in non-escalatable patients

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References

FOAMed

• Nickson C. High-flow nasal cannula. CCC
• Rogers J. High Flow Nasal Cannula. LITFL

Resources

• Rea H, McAuley S, Jayaram L, Garrett J, Hockey H, Storey L, O’Donnell G, Haru L, Payton M, O’Donnell K. The clinical utility of long-term humidification therapy in chronic airway disease. Respir Med. 2010 Apr;104(4):525-33. 
• Helviz Y, Einav S. A Systematic Review of the High-flow Nasal Cannula for Adult Patients. Crit Care 2018; 22: 71
• Parke RL, Bloch A, McGuinness SP. Effect of Very-High-Flow Nasal Therapy on Airway Pressure and End-Expiratory Lung Impedance in Healthy Volunteers. Respir Care. 2015 Oct;60(10):1397-403
• Li J, Albuainain FA, Tan W, Scott JB, Roca O, Mauri T. The effects of flow settings during high-flow nasal cannula support for adult subjects: a systematic review. Crit Care. 2023 Feb 28;27(1):78.