What are the indications for High Flow Nasal Cannula (HFNC) therapy?

Indications for High Flow Nasal Cannula (HFNC)

HFNC is indicated primarily for adults with hypoxemic acute respiratory failure, where it should be used preferentially over conventional oxygen therapy and can be considered over noninvasive ventilation. 1

Primary Indications

Hypoxemic Acute Respiratory Failure

• Use HFNC over conventional oxygen therapy (COT) in hypoxemic ARF as the preferred initial respiratory support modality 1
• Use HFNC over NIV in hypoxemic ARF when both options are available, given superior comfort and tolerance 1
• HFNC provides physiological benefits including high oxygenation, alveolar recruitment, humidification and heating, increased secretion clearance, and reduction of dead space 1
• This indication includes pneumonia, acute respiratory distress syndrome (ARDS), COVID-19 pneumonia, and interstitial lung disease 2

Post-Extubation Respiratory Support

• Use HFNC over COT in nonsurgical patients at low risk of extubation failure to prevent respiratory deterioration 1
• However, use NIV over HFNC for patients at high risk of extubation failure unless contraindications to NIV exist 1
• HFNC following extubation probably reduces treatment failure and need for reintubation in appropriate patient populations 3

Post-Operative Respiratory Support

• Use HFNC over COT in post-operative patients at high risk of pulmonary complications, particularly following cardiac or thoracic surgery 1
• Either HFNC or COT can be used in post-operative patients at low risk of pulmonary complications 1
• Either HFNC or NIV can be used in post-operative patients at high risk of pulmonary complications, with choice based on patient tolerance 1
• HFNC is conditionally recommended postoperatively for high-risk and/or obese patients following cardiac or thoracic surgery 3

Adjunct to NIV Therapy

• Use HFNC over COT during breaks from NIV to maintain adequate oxygenation and respiratory support 1

Secondary and Emerging Indications

Hypercapnic Respiratory Failure

• Trial NIV prior to HFNC in patients with COPD and hypercapnic ARF as NIV remains the preferred modality 1
• HFNC may have an emerging role in acute hypercapnic COPD exacerbations when patients are intolerant to NIV, though this is not yet guideline-endorsed 4

Peri-Intubation Period

• HFNC can be used for pre-oxygenation before intubation in patients with hypoxemic respiratory failure 2, 3
• No formal recommendation exists regarding routine peri-intubation HFNC use 3

Immunocompromised States

• HFNC demonstrates efficacy in immunocompromised patients with acute hypoxemic respiratory failure 2

Palliative Care

• HFNC can provide respiratory support in palliative care settings when intubation is not desired 2

Critical Caveats and Contraindications

Risk of Delayed Intubation

• Prolonging noninvasive respiratory support with either HFNC or NIV in failing patients may result in delayed intubation and worsen hospital mortality 1
• Frequent reassessment is mandatory; patients with severe end organ dysfunction, thoracoabdominal asynchrony, significantly increased respiratory rate, poor oxygenation despite HFNC, and tachycardia are at increased risk of HFNC failure 2

When HFNC is NOT Preferred

• Do not use HFNC as first-line in high-risk extubation patients—NIV is superior unless contraindications exist 1
• Do not use HFNC as first-line in hypercapnic COPD exacerbations—trial NIV first 1
• HFNC has lower ability to unload respiratory muscles compared to NIV 1

Monitoring Requirements

• Reassess patients 30-60 minutes after initiating HFNC to evaluate response 5
• Monitor oxygen saturation, respiratory rate, and work of breathing continuously 5
• Escalate to NIV or intubation promptly if HFNC fails rather than prolonging inadequate support 1

Technical Specifications

Definition and Delivery

• HFNC delivers heated (37°C) and humidified (100% relative humidity) oxygen at high flow rates up to 60 L/min through wide-bore nasal cannulae 6, 2, 7
• HFNC provides a reliable fraction of inspired oxygen (FiO2) and generates low levels of positive end-expiratory pressure (PEEP) 2, 7
• HFNC is distinct from both conventional oxygen therapy and noninvasive ventilation, as it does not require an occlusive interface 6

Common Side Effect Management

• Bloating and aerophagia can occur due to PEEP effects; manage by titrating flow rates downward in 5-10 L/min increments while maintaining adequate oxygenation 5
• Position patients with head of bed elevated 30-45 degrees to reduce abdominal pressure 5
• Encourage proper mouth closure during therapy to optimize airway pressure effects 5