Inclusion Criteria:  Invasive mechanical ventilation started within the past 24 h, or started before ICU admission with ICU admission within the past 24 h, for an expected duration of at least 48 hours after inclusion Treatment with vasoactive agent for shock (adrenaline, dobutamine, or noradrenaline) Nutritional support expected to be started within 24 h after intubation Age older than 18 years Informed consent to participation in the study  Exclusion Criteria:  Invasive mechanical ventilation started more than 24 hours earlier Specific nutritional needs, such as pre-existing long-term home enteral or parenteral nutrition, or for chronic bowel disease Dying patient, not-to-be-resuscitated order, or other treatment limitation decision at ICU admission Pregnancy, recent delivery, or lactation