Is a high-flow nasal cannula effective for relieving tachypnea?

From the Guidelines

High-flow nasal cannula (HFNC) therapy is an effective intervention for relieving tachypnea in many patients. The most recent and highest quality study, published in the European Respiratory Journal in 2022 1, provides evidence-based recommendations for the use of HFNC in adults with acute respiratory failure. To implement HFNC, start with flow rates between 20-60 L/min for adults, with initial FiO2 settings of 40-60% that can be titrated based on oxygen saturation goals. The temperature should be set between 34-37°C for optimal comfort and efficacy. HFNC works by providing several physiological benefits, including:

• Washing out anatomical dead space in the nasopharynx
• Reducing work of breathing
• Delivering consistent FiO2
• Providing a small amount of positive pressure
• Improving mucociliary clearance through humidification

When implementing HFNC, ensure the cannula fits properly in the patient's nares (about 50% of the nostril diameter), monitor for improvement in respiratory rate and work of breathing within 1-2 hours, and be prepared to escalate to non-invasive ventilation or intubation if the patient fails to improve. HFNC is particularly useful for hypoxemic respiratory failure, but may not be sufficient for severe hypercapnic respiratory failure or profound respiratory distress, as noted in the guidelines from the American College of Physicians 1 and the European Respiratory Society 1.

From the Research

Effectiveness of High-Flow Nasal Cannula for Relieving Tachypnea

• The effectiveness of high-flow nasal cannula (HFNC) in relieving tachypnea is discussed in several studies 2, 3, 4, 5.
• A study published in 2020 found that non-invasive respiratory support, including HFNC, may reduce the duration of tachypnea in newborns with transient tachypnea of the newborn (TTN) 2.
• Another study published in 2018 found that HFNC was associated with a reduced need for intubation in patients with acute hypoxemic respiratory failure, but the effect on tachypnea was not specifically reported 3.
• A narrative review published in 2024 suggested that HFNC may be superior to conventional oxygen therapy in avoiding intubation and relieving dyspnea, but the evidence was not specific to tachypnea 4.
• A systematic review published in 2022 found that the evidence for the effect of HFNC on tachypnea was very uncertain due to the limited number of studies and the low quality of the evidence 5.

Comparison with Other Non-Invasive Respiratory Supports

• The studies compared HFNC with other non-invasive respiratory supports, such as continuous positive airway pressure (CPAP) and non-invasive ventilation (NIV) 2, 4, 5.
• The evidence suggested that HFNC may be more effective than CPAP in reducing the duration of tachypnea, but the certainty of the evidence was very low 5.
• The comparison between HFNC and NIV was not conclusive due to the limited number of studies and the low quality of the evidence 4, 5.

Clinical Implications

• The studies suggested that HFNC may be a useful treatment option for patients with acute hypoxemic respiratory failure and tachypnea, but the evidence was not strong enough to support a definitive conclusion 2, 3, 4, 5.
• Further studies are needed to determine the effectiveness of HFNC in relieving tachypnea and to compare it with other non-invasive respiratory supports 4, 5.