High Flow Nasal Cannula Therapy

Primary Indications for Initiating HFNC

The European Respiratory Society recommends starting HFNC immediately as first-line therapy in adults with acute hypoxemic respiratory failure requiring oxygen support beyond conventional oxygen therapy, as it demonstrates reduced intubation rates and superior patient comfort 1, 2
Initiate HFNC when patients have a low oxygenation index, as this threshold demonstrates improved survival compared to both standard oxygen and noninvasive ventilation, with a specific threshold of PaO2/FiO2 ≤ 200 mmHg 2
The European Respiratory Society suggests starting HFNC in patients with acute respiratory distress syndrome, pneumonia, or immunocompromised states presenting with hypoxemic respiratory failure, as HFNC has been shown to be beneficial in these patient populations 1

The European Respiratory Society recommends starting HFNC immediately after extubation in nonsurgical patients at low or moderate risk of extubation failure, defined as absence of weak cough, poor neurological status, or severe cardiac/respiratory disease, as HFNC reduces reintubation rates and need for escalation to NIV 3, 4
For patients at high risk of extubation failure, the European Respiratory Society suggests starting NIV instead of HFNC, unless contraindications to NIV exist, such as intolerance, facial trauma, or claustrophobia 5, 2

The European Respiratory Society recommends initiating HFNC prophylactically in high-risk post-operative patients, particularly following cardiac or thoracic surgery, to prevent pulmonary complications, as HFNC has been shown to reduce the risk of respiratory failure in these patients 3, 2
The European Respiratory Society suggests starting HFNC in obese patients after major surgery who are at elevated risk of respiratory failure, as HFNC has been shown to be beneficial in this patient population 3

The European Respiratory Society recommends against starting HFNC as first-line therapy in patients with COPD and acute hypercapnic respiratory failure with acidosis, as NIV remains the evidence-based standard for hypercapnic acidotic respiratory failure 5
The European Respiratory Society suggests avoiding HFNC as initial therapy in patients who cannot protect their airway, have depressed mental status requiring immediate intubation, or are immediately deteriorating, as these patients require more intensive respiratory support 2

The European Respiratory Society recommends using a flow rate of 50-60 L/min for adults when initiating HFNC, titrating to patient tolerance, as this flow rate has been shown to be effective in providing adequate oxygenation and respiratory support 6
The European Respiratory Society suggests using a temperature of 37°C with 100% relative humidity when initiating HFNC, as this has been shown to be comfortable for patients and effective in providing humidification 6
The European Respiratory Society recommends titrating FiO2 to achieve an oxygen saturation of 92-97% when initiating HFNC, or 88-92% in patients at risk of hypercapnia, as this has been shown to be effective in providing adequate oxygenation while minimizing the risk of hypercapnia 6

The European Respiratory Society recommends reassessing patients 30-60 minutes after initiating HFNC to evaluate response, as this early assessment is crucial to identify treatment failure and avoid delayed intubation, which increases mortality 2

The European Respiratory Society suggests monitoring for failure to improve respiratory rate or persistent tachypnea, as these are high-risk features that require escalation to NIV or intubation 2
The European Respiratory Society recommends monitoring for a rapid shallow breathing index (RSBI) >105 breaths/min/L, as this is a predictor of HFNC failure requiring escalation to NIV or intubation 2
The European Respiratory Society suggests monitoring for tidal volumes persistently >9.5 mL/kg predicted body weight, as this is a predictor of HFNC failure requiring escalation to NIV or intubation 2
The European Respiratory Society recommends monitoring for altered mental status or inability to cooperate, as these are high-risk features that require escalation to NIV or intubation 2
The European Respiratory Society suggests monitoring for hemodynamic instability or tachycardia, as these are high-risk features that require escalation to NIV or intubation 1

The European Respiratory Society recommends using HFNC during breaks from NIV rather than conventional oxygen therapy, as this maintains adequate oxygenation and respiratory support 7, 2
The European Respiratory Society suggests using HFNC in COPD patients on NIV during breaks, as this significantly reduces diaphragm activation and improves comfort without affecting gas exchange 7