Safety and efficacy of high-flow nasal cannula therapy in acute hypercapnic respiratory failure: a retrospective audit

Background While the role of high-flow nasal cannulae (HFNC) in the management of respiratory failure continues to expand, few studies describe its use in acute hypercapnic respiratory failure. Aims In this retrospective study, we assessed the safety and efficacy of HFNC for the treatment of acute hypercapnic respiratory failure. Methods Admissions with acute hypercapnic respiratory failure to a thoracic medicine unit at a tertiary centre between January and August 2018 were included if treated with either HFNC or non-invasive ventilation (NIV). The primary outcome was post-treatment change in arterial pCO(2). Demographics, comorbidities, length of stay, readmission rate and mortality were also collected. Results Sixty-four patients were identified, comprising 69 presentations grouped according to initial treatment: HFNC (n = 24) or NIV (n = 45). Patients in the NIV group had more severe blood gas derangement. In both groups, mean arterial pCO(2) improved significantly (-10 (95% confidence interval: -14 to -6) mmHg) from baseline with no evidence of a differential effect between groups. Six (25%) patients, of whom three had comorbid obesity and two had sleep-disordered breathing, were transitioned from HFNC to NIV. No significant differences in hospital length of stay, 30-day readmission rate or 90-day mortality were observed. Conclusions HFNC might be a reasonable initial treatment for patients with mild acute hypercapnic respiratory failure who do not have comorbid obesity or sleep-disordered breathing. A prospective study might help identify clinical factors or phenotypes predictive of success with this treatment modality.