High-Flow Nasal Oxygen vs. Non-Invasive Ventilation in Acute Cardiogenic Pulmonary Edema: A Comparative Review

Introduction Acute cardiogenic pulmonary edema (ACPE) is a life-threatening manifestation of acute decompensated heart failure, characterized by rapid accumulation of fluid in the alveoli, severe dyspnea, hypoxemia, and increased work of breathing. Prompt respiratory support is essential to stabilize patients, improve gas exchange, and prevent endotracheal intubation. Non-invasive ventilation (NIV), typically in the form of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), has long been the standard non-invasive respiratory therapy for ACPE. Recently, high-flow nasal oxygen (HFNO or HFNC) has emerged as an alternative. This article reviews whether HFNO is as effective as NIV in managing ACPE. Mechanisms of Action Non-Invasive Ventilation (NIV) Positive airway pressure recruits alveoli, reduces intrapulmonary shunting, and improves oxygenation. Reduces preload and afterload by increasing intrathoracic pressure, thereby decreasing venous return and left ventricular afterload. Improves dyspnea and work of breathing by unloading respiratory muscles. High-Flow Nasal Oxygen (HFNO) High flow rates (30–60 L/min) wash out nasopharyngeal dead space, improving CO₂ clearance. Mild positive end-expiratory pressure (PEEP effect), especially at higher flows, though significantly less than NIV. Heated, humidified oxygen improves comfort and tolerance compared to tight-fitting NIV masks. Stable FiO₂ delivery improves oxygenation compared to conventional oxygen therapy. Evidence from Clinical Studies NIV in ACPE Multiple randomized controlled trials and meta-analyses have established NIV as highly effective in ACPE. NIV reduces the need for intubation, improves gas exchange, decreases mortality, and provides rapid relief of dyspnea. It is considered first-line therapy by both the European Society of Cardiology (ESC) and American Heart Association (AHA). HFNO in ACPE Evidence remains limited compared to NIV. Some small trials and observational studies suggest HFNO improves oxygenation and dyspnea compared to standard oxygen, with better patient comfort. However, HFNO has not consistently shown superiority or equivalence to NIV in preventing intubation or improving mortality. Comparative Trials A few recent randomized studies have directly compared HFNO to NIV in ACPE. Results generally show: Oxygenation: HFNO improves oxygenation, but NIV is faster and more effective in severe cases. Dyspnea relief: Both improve symptoms, though NIV shows quicker reduction. Intubation & Mortality: NIV remains superior in reducing intubation rates; mortality benefits of HFNO remain unproven. Meta-analyses (as of 2023) conclude that while HFNO is better tolerated, NIV should remain first-line therapy in ACPE. HFNO may be useful when NIV is contraindicated or not tolerated. Practical Considerations Tolerance & Comfort: HFNO is more comfortable, allows speaking, eating, and expectoration, whereas NIV masks may cause claustrophobia, skin breakdown, and intolerance. Severity of Illness: In moderate-to-severe ACPE with significant respiratory distress or hypercapnia, NIV provides stronger physiological support. Stepwise Approach: HFNO may be reasonable as an initial therapy in mild-to-moderate cases or when NIV is poorly tolerated. NIV should be initiated promptly in more severe cases. Conclusion While high-flow nasal oxygen offers improved comfort and can enhance oxygenation in acute cardiogenic pulmonary edema, current evidence suggests it is not as effective as non-invasive ventilation in rapidly reducing respiratory distress, lowering intubation rates, and improving outcomes. NIV remains the first-line non-invasive respiratory support for ACPE, with HFNO serving as a potential alternative in patients who cannot tolerate NIV or in less severe cases. Future large-scale randomized controlled trials are needed to better define the role of HFNO in ACPE and determine whether specific patient subgroups may benefit from it as a frontline therapy.

High-Flow Nasal Oxygen vs. Non-Invasive Ventilation in Acute Cardiogenic Pulmonary Edema: A Comparative Review

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