High flow through nasal cannula in stable and exacerbated chronic obstructive pulmonary disease patients

Background: High-Flow through Nasal Cannula (HFNC) is a system delivering heated humidified air-oxygen mixture at a flow up to 60 L/min. Despite increasing evidence in hypoxemic acute respiratory failure, a few is currently known in chronic obstructive pulmonary disease (COPD) patients. Objective: To describe the rationale and physiologic advantages of HFNC in COPD patients, and to systematically review the literature on the use of HFNC in stable and exacerbated COPD patients, separately. Methods: A search strategy was launched on MEDLINE. Two authors separately screened all potential references. All (randomized, non-randomized and quasi-randomized) trials dealing with the use of HFNC in both stable and exacerbated COPD patients in MEDLINE have been included in the review. Results: Twenty-six studies have been included. HFNC: 1) provides heated and humidified air-oxygen admixture; 2) washes out the anatomical dead space of the upper airway; 3) generates a small positive end-expiratory pressure; 4) guarantees a more stable inspired oxygen fraction, as compared to conventional oxygen therapy (COT); and 5) is more comfortable as compared to both COT and non-invasive ventilation (NIV). In stable COPD patients, HFNC improves gas exchange, the quality of life and dyspnea with a reduced cost of muscle energy expenditure, compared to COT. In exacerbated COPD patients, HFNC may be an alternative to NIV (in case of intolerance) and to COT at extubation or NIV withdrawal. Conclusion: Though evidence of superiority still lacks and further studies are necessary, HFNC might play a role in the treatment of both stable and exacerbated COPD patients.