Résumé
Background: in non-intubated patients, symptomatic treatment of hypoxemic respiratory failure is still debated with different options: 1) standard oxygen therapy (SOT), 2) high flow nasal cannula oxygen therapy (HFNC) and 3) noninvasive ventilation (NIV). The objective of this study was to compare the effects of HFNC and NIV on lung volumes and upper airway assessed by computed tomography (CT) scan. Material and methods: we conducted a prospective, single-center, physiological, randomized, parallel-group unblinded trial in patients with hypoxemic respiratory failure. Two inspiratory cervicothoracic CT scan were performed, the first after 20 minutes of SOT as part of the routine patient’s management, and the second cervico-thoracic CT scan after 20 minutes of HFNC or NIV depending on the allocation group. The primary outcome was the relative difference in percentage of “non and poorly aerated” lung volumes, before and after the intervention, between the HFNC group and NIV group, assessed by thoracic CT scan. Secondary outcomes included the variation in cross-sectional upper airway area, lung volumes and gas exchange.Results: in these preliminary results, 13 patients have been included (out of the 56 planned) and 10 patients have been analysed. The relative difference in percentage of “non and poorly aerated” lung volumes, before and after intervention, was -8.9% [-4.6; -26.6] in the HFNC group compared to -14.1% [-9.9; -19.8] in the NIV group. Conclusion: in patient with hypoxemic respiratory failure, HFNC and NIV would decrease “non and poorly aerated” lung volumes. These results are only exploratory as the trial is on-going and a significant difference between groups remains to be determined.