Purpose: To investigate whether COVID-19-ARDS differs from all-cause ARDS. Methods: Thirty-two consecutive, mechanically ventilated COVID-19-ARDS patients were compared to two historical ARDS sub-populations 1:1 matched for PaO 2 /FiO 2 or for compliance of the respiratory system. Gas exchange, hemodynamics and respiratory mechanics were recorded at 5 and 15 cmH 2 O PEEP. CT scan variables were measured at 5 cmH 2 O PEEP. Results: Anthropometric characteristics were similar in COVID-19-ARDS, PaO 2 /FiO 2-matched-ARDS and Compliance-matched-ARDS. The PaO 2 /FiO 2-matched-ARDS and COVID-19-ARDS populations (both with PaO 2 /FiO 2 106 ± 59 mmHg) had different respiratory system compliances (Crs) (39 ± 11 vs 49.9 ± 15.4 ml/cmH 2 O, p = 0.03). The Compliance-matched-ARDS and COVID-19-ARDS had similar Crs (50.1 ± 15.7 and 49.9 ± 15.4 ml/cmH 2 O, respectively) but significantly lower PaO 2 /FiO 2 for the same Crs (160 ± 62 vs 106.5 ± 59.6 mmHg, p < 0.001). The three populations had similar lung weights but COVID-19-ARDS had significantly higher lung gas volume (PaO 2 /FiO 2-matched-ARDS 930 ± 644 ml, COVID-19-ARDS 1670 ± 791 ml and Compliance-matched-ARDS 1301 ± 627 ml, p < 0.05). The venous admixture was significantly related to the non-aerated tissue in PaO 2 /FiO 2-matched-ARDS and Compliance-matched-ARDS (p < 0.001) but unrelated in COVID-19-ARDS (p = 0.75), suggesting that hypoxemia was not only due to the extent of non-aerated tissue. Increasing PEEP from 5 to 15 cmH 2 O improved oxygenation in all groups. However, while lung mechanics and dead space improved in PaO 2 /FiO 2-matched-ARDS, suggesting recruitment as primary mechanism, they remained unmodified or worsened in COVID-19-ARDS and Compliance-matched-ARDS, suggesting lower recruitment potential and/or blood flow redistribution. Conclusions: COVID-19-ARDS is a subset of ARDS characterized overall by higher compliance and lung gas volume for a given PaO 2 /FiO 2 , at least when considered within the timeframe of our study.

Purpose: We investigated if the stress applied to the lung during non-invasive respiratory support may contribute to the coronavirus disease 2019 (COVID-19) progression.Methods: Single-center, prospective, cohort study of 140 consecutive COVID-19 pneumonia patients treated in high-dependency unit with continuous positive airway pressure (n = 131) or non-invasive ventilation (n = 9). We measured quantitative lung computed tomography, esophageal pressure swings and total lung stress. Results: Patients were divided in five subgroups based on their baseline PaO 2 /FiO 2 (day 1): non-CARDS (median PaO 2 /FiO 2 361 mmHg, IQR [323-379]), mild (224 mmHg [211-249]), mild-moderate (173 mmHg [164-185]), moderate-severe (126 mmHg [114-138]) and severe (88 mmHg [86-99], p < 0.001). Each subgroup had similar median lung

The mechanisms of CO oxidation on the Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O high-entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal and that Cu(II) can be rapidly reduced to Cu(I) by CO when the temperature is higher than 130 °C. Co and Ni do not have any role in this respect. The Cu(II) oxidation state can be easily but slowly recovered by treatment of the sample with O 2 at ca. 250 °C. However, it should be noted that CuO is readily and irreversibly reduced to Cu(I) when it is treated with CO at T > 100 °C. Thus, the main conclusion of this work is that the high configurational entropy of Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O stabilizes the rock-salt structure and permits the oxidation/reduction of Cu to be reversible, thus permitting the catalytic cycle to take place.