The objective of this study is to compare the difference in daily protein intake of critically ill patients in two standardized enteral nutrition formulas (20% versus 33% percent) with the same caloric density of 1.2 kcal/ml.

The total amount of protein taken in on day four after starting the early enteral feeding is defined as primary endpoint.

For years, the Surgical Intensive Care Unit of the University Hospital Basel has used an early enteral approach for the feeding of critically ill patients with different formulas that have high protein content (20% of total energy). However, the energy goal in the first week is only 20 kcal for normal-weight and 12.5 kcal for obese patients, which results in daily protein amounts of 0.8 to 1 g/kg bodyweight (BW), so that additional protein has to be administered. Due to a suggestion of the dietetic service of the University Hospital Basel, Fresenius Kabi produced a whey based enteral feeding formula for intensive care patients. Specific further adaptations for this patient group included micronutrients and a fatty acid profile as well as low fibres. Surgical Intensive Care Unit of the University Hospital Basel now are offered the opportunity to test this formula in clinical practice and hypothesize that this specific high-protein (30% of energy) enteral formula reaches the same amount of daily caloric intake with a higher total daily amount of protein and equal intestinal tolerance compared to a usual intestinal nutritional formula.

In order to test this hypothesis, investigators plan a double-blind, randomized and controlled study with the aim to achieve a target protein quantity of ≥1.3 g/kg BW with an energy target of 20kcal/kg BW per day, based on a new, specifically designed formula for critically ill patients. The amount of protein on day four after starting the early enteral feeding is defined as primary endpoint. Secondary endpoints are the total amount of calories, the nitrogen balance on day five as well as side effects like gastric residual content, diarrhoea and constipation. Inclusion criteria were an expected stay at the ICU of four days or longer on admission and 18 years of age or older Exclusion criteria consisted of BMI ≤ 18, pregnancy, intestinal perforation, mechanical intestinal obstruction, terminal state of consuming disease, severely impaired liver function and noradrenaline ≥0.5µg/kg BW/min.. On this purpose, 90 critically ill patients will get either of the two enteral feeding products as described above. In case of the event that an increased protein intake can be obtained by the protein-rich formula, an additional study will investigate the influence of early protein-rich nutrition on skeletal muscle wasting with critically ill patients.

In a pre-study investigators will administer the high protein formula to 20 patients to test tolerance and suitability for the nutritional Targets in question. Tolerance will be defined by the absence of one of the following clinical symptoms :

• Reflux
• Diarrhoea
• Constipation
• Nausea
• Vomiting

Inclusion Criteria:

• Adult patients (age 18 years or older)
• expected stay at the ICU of four days upon admittance or longer
• expected enteral feeding during at least four days.

Exclusion Criteria:

• BMI ≤ 18
• Mechanical intestinal obstruction
• Intestinal perforation
• Severely impaired liver function
• Terminal state of consuming disease
• Noradrenaline ≥0.5µg/kg BW/min
• Pregnancy