We found that ΔP was the ventilation variable that best stratified risk. Decreases in ΔP owing to changes in ventilator settings were strongly associated with increased survival. (Funded by Fundação de Amparo e Pesquisa do Estado de São Paulo and others.).

; for the COALITION COVID-19 Brazil III Investigators IMPORTANCE Acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19) is associated with substantial mortality and use of health care resources. Dexamethasone use might attenuate lung injury in these patients. OBJECTIVE To determine whether intravenous dexamethasone increases the number of ventilator-free days among patients with COVID-19-associated ARDS. DESIGN, SETTING, AND PARTICIPANTS Multicenter, randomized, open-label, clinical trial conducted in 41 intensive care units (ICUs) in Brazil. Patients with COVID-19 and moderate to severe ARDS, according to the Berlin definition, were enrolled from April 17 to June 23, 2020. Final follow-up was completed on July 21, 2020. The trial was stopped early following publication of a related study before reaching the planned sample size of 350 patients. INTERVENTIONS Twenty mg of dexamethasone intravenously daily for 5 days, 10 mg of dexamethasone daily for 5 days or until ICU discharge, plus standard care (n =151) or standard care alone (n = 148). MAIN OUTCOMES AND MEASURES The primary outcome was ventilator-free days during the first 28 days, defined as being alive and free from mechanical ventilation. Secondary outcomes were all-cause mortality at 28 days, clinical status of patients at day 15 using a 6-point ordinal scale (ranging from 1, not hospitalized to 6, death), ICU-free days during the first 28 days, mechanical ventilation duration at 28 days, and Sequential Organ Failure Assessment (SOFA) scores (range, 0-24, with higher scores indicating greater organ dysfunction) at 48 hours, 72 hours, and 7 days. RESULTS A total of 299 patients (mean [SD] age, 61 [14] years; 37% women) were enrolled and all completed follow-up. Patients randomized to the dexamethasone group had a mean 6.6 ventilator-free days (95% CI, 5.0-8.2) during the first 28 days vs 4.0 ventilator-free days (95% CI, 2.9-5.4) in the standard care group (difference, 2.26; 95% CI, 0.2-4.38; P = .04). At 7 days, patients in the dexamethasone group had a mean SOFA score of 6.1 (95% CI, 5.5-6.7) vs 7.5 (95% CI, 6.9-8.1) in the standard care group (difference, −1.16; 95% CI, −1.94 to −0.38; P = .004). There was no significant difference in the prespecified secondary outcomes of all-cause mortality at 28 days, ICU-free days during the first 28 days, mechanical ventilation duration at 28 days, or the 6-point ordinal scale at 15 days. Thirty-three patients (21.9%) in the dexamethasone group vs 43 (29.1%) in the standard care group experienced secondary infections, 47 (31.1%) vs 42 (28.3%) needed insulin for glucose control, and 5 (3.3%) vs 9 (6.1%) experienced other serious adverse events. CONCLUSIONS AND RELEVANCE Among patients with COVID-19 and moderate or severe ARDS, use of intravenous dexamethasone plus standard care compared with standard care alone resulted in a statistically significant increase in the number of ventilator-free days (days alive and free of mechanical ventilation) over 28 days.

None.

EIT is cheap, noninvasive and allows continuous monitoring of ventilation. It is gaining acceptance as a valuable monitoring tool for the care of critical patients.

Objective-Regional tidal lung strain may trigger local inflammation during mechanical ventilation, particularly when additional inflammatory stimuli are present. However, it is unclear whether inflammation develops proportionally to tidal strain or only above a threshold. We aimed to: (1) assess the relationship between regional tidal strain and local inflammation in vivo during the early stages of lung injury in lungs with regional aeration heterogeneity comparable to that of humans; and (2) determine how this strain-inflammation relationship is affected by endotoxemia. Design-Interventional animal study.Setting-Experimental laboratory and positron emission tomography (PET) facility. Subjects-Eighteen 2-4-month-old sheep.Interventions-Three groups of sheep (n=6) were mechanically ventilated to the same plateau pressure (30-32 cmH 2 O) with High-Strain (V T =18.2±6.5 ml/kg, PEEP=0), High-Strain plus intravenous lipopolysaccharide (LPS) (V T =18.4±4.2 ml/kg, PEEP=0), or Low-Strain plus LPS (V T =8.1±0.2 ml/kg, PEEP=17±3 cmH 2 O). At baseline, we acquired respiratory-gated PET scans Conclusions-Local inflammation develops proportionally to regional tidal strain during early lung injury. The regional inflammatory effect of strain is greatly amplified by intravenous LPS. Tidal strain enhances local 18 F-FDG uptake primarily by increasing the rate of intracellular 18 F-FDG phosphorylation.

Background There is limited information on the regional inflammatory effects of mechanical ventilation and endotoxemia on the production of acute lung injury. Measurement of 18F-fluorodeoxyglucose (18F-FDG) uptake with Positron Emission Tomography allows for the regional, in vivo and non-invasive, assessment of neutrophilic inflammation. We tested whether mild endotoxemia combined with large tidal volume mechanical ventilation bounded by pressures within clinically acceptable limits could yield measurable and anatomically localized neutrophilic inflammation. Methods Sheep were mechanically ventilated with plateau pressures=30–32 cmH2O and positive end-expiratory pressure=0 for 2h. Six sheep received IV endotoxin (10 ng.kg−1.min−1) while 6 did not (controls), in sequentially performed studies. We imaged with Positron Emission Tomography the intrapulmonary kinetics of infused 13N-nitrogen and 18F-FDG to compute regional perfusion and 18F-FDG uptake. Transmission scans were used to assess aeration. Results Mean gas fraction and perfusion distribution were similar between groups. In contrast, a significant increase in 18F-FDG uptake was observed in all lung regions of the endotoxin group. In this group, 18F-FDG uptake in middle and dorsal regions was significantly larger than that in ventral regions. Multivariate analysis showed that 18F-FDG uptake was associated with regional aeration (p<0.01) and perfusion (p<0.01). Conclusions Mild short-term endotoxemia in the presence of heterogeneous lung aeration and mechanical ventilation with pressures within clinically acceptable limits produces marked spatially heterogeneous increases in pulmonary neutrophilic inflammation. The dependence of inflammation on aeration and perfusion suggests a multifactorial basis for that finding. 18F-FDG uptake may be a sensitive marker of pulmonary neutrophilic inflammation in the studied conditions.

In this series of ARDS patients receiving ECMO for refractory hypoxemia, driving pressure during ECMO was the only ventilator setting that showed an independent association with in-hospital mortality.

Extracorporeal membrane oxygenation (ECMO) has gained renewed interest in the treatment of respiratory failure since the advent of the modern polymethylpentene membranes. Limited information exists, however, on the performance of these membranes in terms of gas transfers during multiple organ failure (MOF). We investigated determinants of oxygen and carbon dioxide transfer as well as biochemical alterations after the circulation of blood through the circuit in a pig model under ECMO support before and after induction of MOF. A predefined sequence of blood and sweep flows was tested before and after the induction of MOF with fecal peritonitis and saline lavage lung injury. In the multivariate analysis, oxygen transfer had a positive association with blood flow (slope = 66, P<0.001) and a negative association with pre-membrane PaCO2 (slope = −0.96, P = 0.001) and SatO2 (slope = −1.7, P<0.001). Carbon dioxide transfer had a positive association with blood flow (slope = 17, P<0.001), gas flow (slope = 33, P<0.001), pre-membrane PaCO2 (slope = 1.2, P<0.001) and a negative association with the hemoglobin (slope = −3.478, P = 0.042). We found an increase in pH in the baseline from 7.50[7.46,7.54] to 7.60[7.55,7.65] (P<0.001), and during the MOF from 7.19[6.92,7.32] to 7.41[7.13,7.5] (P<0.001). Likewise, the PCO2 fell in the baseline from 35 [32,39] to 25 [22,27] mmHg (P<0.001), and during the MOF from 59 [47,91] to 34 [28,45] mmHg (P<0.001). In conclusion, both oxygen and carbon dioxide transfers were significantly determined by blood flow. Oxygen transfer was modulated by the pre-membrane SatO2 and CO2, while carbon dioxide transfer was affected by the gas flow, pre-membrane CO2 and hemoglobin.