IL6 and Multiple Organ Failure: The main findings were: a) IL-6 blood concentrations were high but exceeded 1000 pg/mL in less than 10% of measurements; b) the correlation of IL-6 with other available biological variables was relatively poor so IL-6 levels cannot be extrapolated from other variables in this setting; c) higher IL-6 levels were observed in ECMO patients when compared to others, but no other critical conditions, including multiple organ failure and hypoxemia, was associated with high IL-6 levels; d) the maximal IL-6 value over the ICU stay was associated with ICU mortality.