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BackgroundThe study objective was to compare titration of positive end-expiratory pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded pressure–volume loop in severe acute respiratory distress syndrome (ARDS).MethodsWe have designed a prospective study with historical control group. Twenty-four severe ARDS patients (arterial oxygen partial pressure to fractional inspired oxygen ratio, PaO2/FiO2 < 100 mmHg) were included in the EIT group and examined prospectively. Data from another 31 severe ARDS patients were evaluated retrospectively (control group). All patients were receiving medical care under identical general support guidelines and protective mechanical ventilation. The PEEP level selected in the EIT group was the intercept point of cumulated collapse and overdistension percentages curves. In the control group, optimal PEEP was selected 2 cmH2O above the lower inflection point on the static pressure–volume curve.ResultsPatients in the EIT group were younger (P < 0.05), and their mean plateau pressure was 1.5 cmH2O higher (P < 0.01). No differences in other baseline parameters such as APACHE II score, PaO2/FiO2, initial PEEP, driving pressure, tidal volume, and respiratory system compliance were found. Two hours after the first PEEP titration, significantly higher PEEP, compliance, and lower driving pressure were found in the EIT group (P < 0.01). Hospital survival rates were 66.7% (16 of 24 patients) in the EIT group and 48.4% (15 of 31) in the control group. Identical rates were found regarding the weaning success rate: 66.7% in the EIT group and 48.4% in the control group.ConclusionIn severe ARDS patients, it was feasible and safe to guide PEEP titration with EIT at the bedside. As compared with pressure–volume curve, the EIT-guided PEEP titration may be associated with improved oxygenation, compliance, driving pressure, and weaning success rate. The findings encourage further randomized control study with a larger sample size and potentially less bias in the baseline data.Trial Registration NCT03112512Electronic supplementary materialThe online version of this article (10.1186/s13613-019-0484-0) contains supplementary material, which is available to authorized users.

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formed gels and showed liquid crystalline structures at high concentrations. The absorption properties of poly(3-hexylthiophene) showed dramatic changes during gelation, which is an indication of strong intermolecular π-electronic coupling of the ordered self-assembled poly(3-hexylthiophene) gels. The effect of conformational transitions on the photovoltaic properties of solution-processed poly(3hexylthiophene)/fullerene blends has been studied in this Article. It is shown that the photovoltaic performance is strongly affected by gelation, which alters the morphology of the photoactive layer. Device optimization yields solar cells with a power conversion efficiency of 3.78% under standard test conditions (AM 1.5, 100 mW/cm 2 ).