Background Awake prone position is an emerging rescue therapy applied in patients undergoing noninvasive ventilation (NIV) for acute hypoxemic respiratory failure (ARF) related to novel coronavirus disease (COVID-19). Although applied to stabilize respiratory status, in awake patients, the application of prone position may reduce comfort with a consequent increase in the workload imposed on respiratory muscles. Thus, we primarily ascertained the effect of awake prone position on diaphragmatic thickening fraction, assessed through ultrasound, in COVID-19 patients undergoing NIV. Methods We enrolled all COVID-19 adult critically ill patients, admitted to intensive care unit (ICU) for hypoxemic ARF and undergoing NIV, deserving of awake prone positioning as a rescue therapy. Exclusion criteria were pregnancy and any contraindication to awake prone position and NIV. On ICU admission, after NIV onset, in supine position, and at 1 h following awake prone position application, diaphragmatic thickening fraction was obtained on the right side. Across all the study phases, NIV was maintained with the same setting present at study entry. Vital signs were monitored throughout the entire study period. Comfort was assessed through numerical rating scale (0 the worst comfort and 10 the highest comfort level). Data were presented in median and 25th–75th percentile range. Results From February to May 2021, 20 patients were enrolled and finally analyzed. Despite peripheral oxygen saturation improvement [96 (94–97)% supine vs 98 (96–99)% prone, p = 0.008], turning to prone position induced a worsening in comfort score from 7.0 (6.0–8.0) to 6.0 (5.0–7.0) (p = 0.012) and an increase in diaphragmatic thickening fraction from 33.3 (25.7–40.5)% to 41.5 (29.8–50.0)% (p = 0.025). Conclusions In our COVID-19 patients assisted by NIV in ICU, the application of awake prone position improved the oxygenation at the expense of a greater diaphragmatic thickening fraction compared to supine position. Trial registration ClinicalTrials.gov, number NCT04904731. Registered on 05/25/2021, retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04904731.

Background This single-center preliminary prospective observational study used bedside ultrasound to assess the lung aeration modifications induced by recruitment maneuver and pronation in intubated patients with acute respiratory disease syndrome (ARDS) related to coronavirus 2019 disease (COVID-19). All adult intubated COVID-19 patients suitable for pronation were screened. After enrollment, patients underwent 1 h in a volume-controlled mode in supine position (baseline) followed by a 35-cmH2O-recruitment maneuver of 2 min (recruitment). Final step involved volume-controlled mode in prone position set as at baseline (pronation). At the end of the first two steps and 1 h after pronation, a lung ultrasound was performed, and global and regional lung ultrasound score (LUS) were analyzed. Data sets are presented as a median and 25th–75th percentile. Results From January to May 2022, 20 patients were included and analyzed. Global LUS reduced from 26.5 (23.5–30.0) at baseline to 21.5 (18.0–23.3) and 23.0 (21.0–26.3) at recruitment (p < 0.001) and pronation (p = 0.004). In the anterior lung regions, the regional LUS were 1.8 (1.1–2.0) following recruitment and 2.0 (1.6–2.2) in the supine (p = 0.008) and 2.0 (1.8–2.3) in prone position (p = 0.023). Regional LUS diminished from 2.3 (2.0–2.5) in supine to 2.0 (1.8–2.0) with recruitment in the lateral lung zones (p = 0.036). Finally, in the posterior lung units, regional LUS improved from 2.5 (2.3–2.8) in supine to 2.3 (1.8–2.5) through recruitment (p = 0.003) and 1.8 (1.3–2.2) with pronation (p < 0.0001). Conclusions In our investigation, recruitment maneuver and prone positioning demonstrated an enhancement in lung aeration when compared to supine position, as assessed by bedside lung ultrasound. Trial registration: www.clinicaltrials.gov, Number NCT05209477, prospectively registered and released on 01/26/2022.