From the Guidelines
High Flow Nasal Cannula (HFNC) is preferred over Continuous Positive Airway Pressure (CPAP) nasal prongs for patients with hypoxaemic acute respiratory failure due to its ability to provide mild positive pressure and improved patient comfort. The main differences between HFNC and CPAP nasal prongs lie in their delivery mechanisms and pressure support capabilities. HFNC delivers heated, humidified oxygen at high flow rates (up to 60 L/min in adults) through larger nasal prongs, providing mild positive pressure (2-5 cmH2O) that varies with breathing 1. In contrast, CPAP nasal prongs deliver a constant fixed pressure (typically 5-20 cmH2O) throughout the respiratory cycle, creating more consistent airway support.
Key differences between HFNC and CPAP include:
- Flow rates: HFNC can deliver higher flow rates than CPAP
- Pressure support: CPAP provides more reliable and consistent pressure support than HFNC
- Patient comfort: HFNC is generally more comfortable and better tolerated than CPAP, allowing patients to eat, drink, and speak while receiving therapy
- Clinical applications: HFNC is suitable for patients needing oxygen supplementation and mild respiratory support, while CPAP is typically chosen for patients with obstructive sleep apnea, acute pulmonary edema, or those requiring more definitive pressure support. According to the European Respiratory Society task force panel, HFNC is recommended over conventional oxygen therapy (COT) and noninvasive ventilation (NIV) in certain cases of acute respiratory failure 1.
The choice between HFNC and CPAP ultimately depends on the patient's specific respiratory needs, comfort considerations, and clinical condition, with HFNC often serving as an intermediate step between conventional oxygen therapy and CPAP or mechanical ventilation. As stated in the European Respiratory Journal, the use of HFNC alongside other noninvasive forms of respiratory support in adults with acute respiratory failure is supported by recent evidence 1.
From the Research
Overview of HFNC and CPAP
- High Flow Nasal Cannula (HFNC) and Continuous Positive Airway Pressure (CPAP) are two respiratory support techniques used in various clinical settings.
- HFNC delivers high flow, heated and humidified controlled concentration of oxygen via the nasal route 2.
- CPAP is a type of non-invasive ventilation that provides a constant flow of air pressure into the airways to keep them open 3.
Comparison of HFNC and CPAP
- Studies have compared the effectiveness of HFNC and CPAP in patients with respiratory distress, including bronchiolitis and acute respiratory failure.
- One study found that HFNC reduced the risk of treatment failure by nearly half compared to standard oxygen therapy, but had a slightly elevated risk of treatment failure compared to CPAP in moderate to severe bronchiolitis 4.
- Another study found that HFNC was associated with a higher risk of treatment failure and possibly an increased risk of need for intubation and mortality compared to CPAP in children with respiratory distress younger than 2 years 3.
- However, HFNC has been shown to have improved tolerance, a lower complication rate, and is more easily available in peripheral hospitals compared to CPAP 4.
Physiological Benefits of HFNC
- HFNC has several physiological benefits, including reduced anatomical dead space, PEEP, constant F(IO2), and good humidification 5.
- HFNC has been shown to decrease breathing frequency and work of breathing, and reduce the need for respiratory support escalation in critically ill adults 5.
Clinical Indications for HFNC and CPAP
- HFNC is recommended for use in patients with hypoxemic respiratory failure, following extubation, and postoperatively for high-risk and/or obese patients following cardiac or thoracic surgery 2.
- CPAP is commonly used in patients with respiratory distress, including those with acute respiratory failure and bronchiolitis 3.
- The choice between HFNC and CPAP depends on the individual patient's needs and clinical circumstances, and should be guided by evidence-based recommendations and clinical guidelines 2, 4, 3.