When patients survive a life-threatening condition in the intensive care unit (ICU), they often face a prolonged recovery process marked by persistent health issues that significantly reduce their quality of life. Muscle weakness is the most defining feature of this post-intensive care syndrome. This weakness, along with the associated decline in quality of life, presents major challenges for patients, their families, and the healthcare system, including the high costs of long-term care.

Until recently, it was believed that providing additional nutrition-particularly protein-during the early phase of a critical illness could help prevent muscle loss and promote recovery. However, the recent PRECISe study showed that administering a high amount of protein (target: 2 g/kg per day) via feeding tube actually worsened outcomes: patients who received high-protein nutrition during the acute phase reported a lower quality of life over the six months following ICU admission and were discharged from the hospital later.

These findings from the PRECISe study have renewed attention on the amount of protein administered to critically ill patients. Current European ICU nutrition guidelines (1.3 g/kg per day) recommend a higher protein intake than the daily recommended amount for healthy individuals (0.8 g/kg per day). However, in critically ill patients, protein metabolism may be impaired, potentially leading to the accumulation of toxic protein breakdown products and hindering recovery, ultimately resulting in a lower quality of life.

Reducing protein intake below the level recommended for healthy individuals during the acute phase of a life-threatening illness-while maintaining total energy intake (calories)-may be beneficial for long-term recovery and rehabilitation.

The PRECISe-2 study investigates whether patients who receive less protein (0.6-0.8 g/kg per day) but sufficient energy during the early phase of their critical illness feel better and experience a higher quality of life in the long term compared to those who receive the standard amount of protein (1.3 g/kg per day).

Inclusion Criteria:

• Adult (≥ 18 years-old) patient
• Admission to the ICU
• Invasive, mechanical ventilation initiated within 72 hours following ICU admission, or mechanically ventilated upon arrival to the ICU
• Expected ICU stay on mechanical ventilation of ≥ 3 days after randomisation

Exclusion Criteria:

• Expected contra-indication for enteral nutrition for at least one week, at the discretion of the treating physician, such as a bowel discontinuity that cannot be solved within one week
• Moribund (expected to die within 48 hours) or withholding of treatment (DNR code 3)
• Previous inclusion in the PRECISe-2 trial
• Transfer from another ICU with an ICU stay longer than 3 days