Covid-19 versus Non-Covid-19 Acute Hypoxemic Respiratory Failure (AHRF). Helmet-CPAP (H-CPAP) treatment.

<bold>Introduction:</bold> Although many studies have provided data from patients with Covid-19, few have directly compared Covid-19 and non-Covid AHRF. <bold>Aims and objectives:</bold> Comparison of two large groups of patients with AHRF secondary to Covid and non-Covid pneumonia treated with H-CPAP. <bold>Methods:</bold> In this observational, retrospective study conducted in Vimercate’s Hospital Respiratory Intermediate Care Unit (RICU), we collected data regarding patients with non-Covid (Group A n. 167) and Covid (Group B n. 515) pneumonia related AHRF with PaO2/FiO2 ratio ≤ 300 in H-CPAP. Patients with multiorgan failure were excluded. We obtained data at admission and 1 hour after H-CPAP initiation. A two-sample test was used to compare two groups. All tests were 2-tiled and the statistical significance was p<0,05. <bold>Results:</bold> The two groups were similar in age (group A: 63,2±14 vs. group B: 62.5±11). PaO2/FiO2 in high flow oxygen therapy (Venturi mask or non-rebreathing oxygen mask) was lower in group A compared to group B (125±50.7 vs. 147,3±68,4, p<0,0001). The same evidence was found for PaO2/FiO2 in H-CPAP (group A: 162,6±59,1 vs. group B: 210,4±91,4, p<0,0001). APACHE 2 score was higher in A vs. B (15,4±5,3 vs. 10,16±4,4, p<0,0001). H-CPAP success (hospital discharge without intubation) was 78,4% in A vs. 70% in B (p<0,032). Mortality rate was A: 10,1% vs. B: 17,6% (p<0,004). <bold>Conclusions:</bold> H-CPAP is an effective treatment for AHRF in both groups. Despite non-Covid have a higher disease severity at admission, their outcome was better. This result can be explained by the worsening biphasic trend of Covid pneumonia, due to evolution from phase L to H during hospitalization.