Impact of Supplemental Parenteral Nutrition in ICU Patients on Metabolic, Inflammatory and Immune Responses

Enrollment on day 3 of critically ill patients, without contraindication to EN, not achieving 60% of the ICU per protocol energy target.

Intervention: Randomization to either continued pure EN, or from day 4 to supplemental PN to complete EN at target validated by indirect calorimetry.

Measurements: Indirect calorimetry on Days 3, 4, 9 (twice). Primary endpoints = glucose and leucine metabolism On days 4 and 9-10: isotopic investigation of glucose metabolism, and immune and inflammatory responses// Day 9-10: isotopic investigation of protein (leucine) metabolism Secondary endpoints: Insulin requirements, area under the curve (AUC) of blood Glucose, infections after day 9, overall complications, length of mechanical ventilation, of ICU and hospital stay.

Inclusion criteria

• estimated duration of ICU stay > 5 days,
• estimated survival > 7 days,
• absence of contraindication to EN
• need for mechanical ventilation
• informed consent obtained from patients, close relative, or referring physician

Exclusion criteria

• refusal of the patient or of the next of kin
• age < 18 years
• non-functional digestive tract (short bowel, persistent ileus, proximal intestinal fistula high rate > 1.5 litres/day)
• already receiving PN before Day 3
• absence of a central venous catheter
• women who are pregnant (pregnancy test).
• Admission after cardiac arrest, or severe brain injury