High-flow nasal cannula versus noninvasive ventilation on lung re-aeration and diaphragm function

Abstract

Background: High-flow nasal cannula (HFNC) has been shown to induce lung recruitment and reduce respiratory muscle loading. Aims and Objectives: To compare the effects of HFNC vs noninvasive ventilation (NIV) on lung re-aeration and diaphragm function in patients with acute respiratory failure (ARF). Methods: Twenty spontaneously breathing patients were prospectively studied. They received three 60-minutes trials with HFNC (60L/min), NIV and standard oxygen (O2) applied in random order. After each trial, lung ultrasound aeration score (LUS), diaphragm thickening fraction (DTF) and diaphragm excursion (DE) were assessed by ultrasonography. LUS, DTF and DE among the 3 trials were compared with one-way ANOVA followed by post-hoc analysis. Results: NIV induced a significant reduction in LUS, DTF and a significant increase in DE compared to standard O2 and HFNC. LUS, DTF and DE were not different between HFNC and standard O2 (Table). Conclusions: In patients with ARF, the use of HFNC for 60 minutes had no significant short-term effect on lung recruitment, DTF or DE compared to standard O2. NIV induced a significantly greater lung re-aeration. The significant reduction of DTF with NIV may indicate a decrease in patient’s respiratory effort. Further studies are needed to compare intermittent NIV with continuous HFNC when they are applied for longer periods.