Rapid Recognition of Corticosteroid Resistant or Sensitive Sepsis

Main objective and primary endpoint: To compare the effect hydrocortisone plus fludrocortisone vs. placebo on a composite of death or persistent organ dysfunction - defined as continued dependency on mechanical ventilation, new renal replacement therapy, or vasopressors - assessed at 90 days on intensive care unit (ICU) adults and having different biological profiles for immune responses and corticosteroids bioactivity. Secondary objectives and endpoints: * Mortality and health-related quality of life at 6 months; * Daily organ function (SOFA score days 1, 2, 3, 4, 7, 10, 14, 28, and 90); * Daily secondary infections (up to 90 days) * Daily blood and urinary levels of glucose, sodium and potassium (up to 28 day) * Daily gastroduodenal bleeding (up to 28 day) * Daily cognitive function and muscles' strength (days 1 to 28, 90 and 180 days).