Fig. 1.

Study cohort flowchart. A, The first consecutive 23 COVID-19 patients treated on our ICU were enrolled to this study, investigating PEEP and prone positioning in mechanically ventilated patients. Eight patients were excluded from the assessment of the specific interventions as they received ECMO therapy (three patients, ECMO therapy would interfere with the analysis of oxygenation), or high-flow oxygen therapy but no mechanical ventilation (five patients that could not be asses regarding the effects of invasive mechanical ventilation, PEEP and prone positioning), resulting in 15 patients eligible for this study. Ten patients were intubated in our ICU (Subset 1, intubation group), while eight patients were transferred intubated to our ward. For seven of the 15 mechanically ventilated patients, a full dataset of decremental PEEP trials was available and they were accordingly included in Subset 2 (PEEP trial analysis) for determination of optimal PEEP. Nine of the fifteen patients were subject to prone positioning (Subset 3, prone position analysis). B, Illustration of the allocation of the 15 patients to each analysis.