Lower flow rates (20-30 LPM) when administering high-flow oxygen therapy had superior efficacy in lowering PaCO2 levels in patients suffering acute exacerbations of COPD (AECOPD).
For millions living with chronic obstructive pulmonary disease (COPD), the simple act of breathing can feel like a losing battle against a tightening chest and a persistent cough. When symptoms escalate into an acute exacerbation, the stakes rise sharply, often leading to respiratory failure and a dangerous buildup of carbon dioxide in the blood.1
Traditionally, doctors have relied on non-invasive ventilation (NIV) to support these patients, but the heavy masks can be claustrophobic and cause painful facial sores.1 A newer, more comfortable alternative called high-flow nasal cannula (HFNC) has gained popularity, yet medical professionals have lacked a consensus on the “Goldilocks” setting—the ideal initial flow of oxygen to stabilize a patient in crisis.1
A comprehensive study published in the journal Pulmonology and drawn from the sources provides a new roadmap for clinicians.1 By analyzing 40 randomized controlled trials involving 3,597 patients, researchers determined that starting at a “low” flow rate (20 to 30 liters per minute) is the most effective strategy for lowering carbon dioxide levels and restoring healthy blood pH.1
While the sources indicate that moderate flow rates (30 to 50 liters per minute) were the most successful at shortening hospital stays, the low-flow setting was ultimately crowned the preferred choice because it maximized patient comfort and minimized the risk of nasal and facial injuries.1 Interestingly, the analysis found that HFNC was comparable to traditional NIV in preventing the need for invasive intubation, making it a viable, more tolerable first-line defense.1
The superiority of low-flow settings is rooted in delicate lung mechanics. While high-flow rates can inadvertently trap air in the lungs and fatigue respiratory muscles, a lower flow provides just enough pressure to assist the body’s natural rhythm without overtaxing it.1
Ding L. et al. Comparison of the efficacy of high-flow nasal cannula with different initial flow settings in patients with acute exacerbations of chronic obstructive pulmonary disease: A systematic review and network meta-analysis. 2025. Pulmonology, 31(1). https://doi.org/10.1080/25310429.2025.2598913