Chronic obstructive pulmonary disease is a common lung disease. Acute exacerbations (AECOPD) are associated with increased hospitalisations and mortality. Current guidelines provide only conditional recommendation for the use of High Flow Nasal Cannula (HFNC) supported by low-certainty evidence in hypercapnic respiratory failure. Since then, additional studies have been published, and we aimed to review the available literature on HFNC as a first-line therapy in hypercapnic AECOPD.

Structured literature research was performed in PubMed and Embase to include studies assessing HFNC as a first-line therapy in hypercapnic AECOPD and focusing on clinical outcomes (dyspnoea, blood gas, treatment failure, mortality). Studies were categorized as single-arm studies, comparisons with conventional oxygen therapy (COT), or comparisons with non-invasive ventilation (NIV).

Among 17 articles included, 2 were uncontrolled, 3 articles compared HFNC to COT and 12 compared HFNC to NIV. HFNC was often associated with better comfort and tolerance. Compared to COT, HFNC might reduce treatment failure, but evidence is still scarce. Compared to NIV, HFNC had similar effects on dyspnoea and blood gas analysis in most studies, but it remains uncertain considering treatment failure.

In hypercapnic AECOPD, HFNC remains an alternative therapeutic option as compared to COT but also to NIV when the latter is contraindicated, not tolerated or during breaks from NIV. Further research is warranted with well-designed RCT focusing on treatment failure and mortality. In the future, patients might be selected considering some endotypes of AECOPD such as bronchorrhea, sleep apnea overlap or disproportionate dyspnoea which could benefit differently from HFNC.