A randomized crossover clinical study comparing free flow helmet CPAP with full face mask CPAP in acute hypoxemic respiratory failure

Data on physiological comparison of helmet CPAP (H-CPAP) and mask CPAP (M-CPAP) in patients with acute hypoxemic respiratory failure (AHRF) are limited. The study aimed to compare gas exchange, respiratory mechanics, inspiratory effort, and comfort between CPAP interfaces. We prospectively included patients with AHRF ( n = 30), that received H-CPAP and M-CPAP in a randomized crossover design. We registered the following parameters (on room air, during H-CPAP, and M-CPAP): respiratory rate (RR), respiratory muscles work (Patrick scale), VAS comfort, arterial blood gas, esophageal pressure (P ES ), and airway pressure (P AW ). We calculated PaO 2 /FiO 2 , ROX index, ∆P ES , P ES -simplified pressure-time product (P ES -PTP), directly measured transpulmonary pressure (P L and ∆P L ). PaO 2 /FiO 2 , PaCO 2 and ROX index did not differ between H-CPAP and M-CPAP. RR during H-CPAP was lower vs. M-CPAP ( p = 0.001). VAS comfort was 7.0 (6.8-8.0) points during H-CPAP vs. 5.0 (4.0–5.0) points during M-CPAP ( p < 0.001 for all). Patrick score was 2.0 (1.0–2.0) points during H-CPAP vs. 2.5 (2.0–3.0) points during M-CPAP ( p < 0.001). ∆P ES 7.7 (5.2–9.5) cmH 2 O during H-CPAP vs. 13.9 (10.3–16.9) cmH 2 O during M-CPAP ( p < 0.001). P ES -PTP per minute was 144 (88–180) cmH 2 O*s*min -1 during H-CPAP vs. 278 (195–363) cmH 2 O*s*min -1 during M-CPAP ( p < 0.001). ∆P L was 5.2 (3.6–7.5) cmH 2 O during H-CPAP vs. 12.9 (9.1–16.8) cmH 2 O during M-CPAP ( p < 0.001). In patients with AHRF H-CPAP as compared with M-СPAP improved comfort, decreased RR, work of accessory respiratory muscles, inspiratory effort, and driving transpulmonary pressure without changes in oxygenation and PaCO 2 . Trial registration: The study registered on Clinical Trials registry on October 27, 2023 (retrospectively registered). ClinicalTrials.gov identifier NCT06113432, Trial registration: https//clinicaltrials.gov/study/NCT06113432?term=NCT06113432&rank=1&a=3.