IL6 and acute respiratory distress syndrome: Plasma IL-6 levels were also not different when comparing subgroups, based on ARDS severity at ICU admission, median compliance of the respiratory system (above or below the median value of 36.6 ml/cmH2O), or based on baseline levels of IL-6 levels (above or below the median value of 12.7 pg/ml) (supplementary Figure S4).