Fig. 4

The gas exchange, respiratory mechanics and plethysmogram varia-bility during 28 days of the mechanical ventilation in survivors and non-survivors. A PaO2/FiO2. B Ventilatory ratio. C Alveolar dead space to tidal volume ratio. D Static compliance of the respiratory system. E The «optimum» positive end ex-piratory pressure balanced between the lowest driving pressure and the highest pe-ripheral oxygen saturation (SpO2). F Change in plethysmogram variability index during the recruitment maneuver (Days 1 and 7) or the tidal volume increase by 200 ml (on Days 3, 5,10,14, 21 and 28). Data on survivors (black) and non-survivors (grey) is presented as medians and 95% confidence in-tervals. The x-axis represents days after initiation of the mechanical ventilation. Abbreviations: PaO2- partial pressure of oxygen in arterial blood; FiO2—inspiratory oxygen fraction; VDalv—alveolar dead space: VT- tidal volume; PEEP—positive end-expiratory pressure; PVI—ple-thysmogram variability index; SpO2 peripheral oxygen saturation.* p-value < 0.05, comparison between survivors and non-survivors (Mann-Whitney U test) ;** p-value < 0.01, comparison between survivors and non-survivors (Mann-Whitney U test) ;§ p-value < 0.001, comparison between survivors and non-survivors (Mann-Whitney U test)