The aim of this clinical trial is to assess the efficacy and safety of the investigational product SmofKabiven extra Nitrogen in patients requiring parenteral nutrition (PN) to achieve the target protein dose. The cumulative target protein dose is 6.2 g per kg of body weight (BW) over the five study treatment days, with 1.0 g/kg BW on Study Day 1 and 1.3 g/kg BW per day on Study Days 2-5; the target caloric intake is 15 kcal/kg BW on Study Day 1 and 20 kcal/kg BW/day on Study Days 2-5, following the recommendation of the ESPEN guideline on clinical nutrition in the intensive care unit 2019 regarding a slow-ramp up of calories during the first week of critical illness.

Inclusion Criteria:

• Age ≥ 18 years and < 90 years, male or female
• Critically ill, medical or surgical intensive care unit (ICU) patient
• The patient was admitted to the ICU during the previous 24-48 hours and has a minimum expected ICU stay of 5 days after the completion of screening
• Central venous access available for continuous infusion of the investigational product
• Contraindication against EN or limited tolerance to EN; it is planned that the patient receives ≥75% of the total target caloric intake from PN during the 5 investigational product treatment days
• Informed consent (signed and dated) from the patient to participate in this clinical trial. If the patient is unable to make a decision because of his/her critical condition, a decision regarding study enrolment is made at a case conference involving three physicians

Exclusion Criteria:

• Contraindication against PN or inability to receive PN via central venous access

• The patient has received PN within the last 7 days before the start of screening

• Body mass index (BMI) <18.5 kg/m2 or >35 kg/m2

• Any severe, persistent blood coagulation disorder with uncontrolled bleeding

• Any congenital errors of amino acid metabolism

• Uncontrolled hyperglycaemia despite insulin treatment

• Known hypersensitivity to fish, egg, soybean proteins, peanut proteins, or to any of the active ingredients or excipients contained in SmofKabiven extra Nitrogen

• General contraindications to infusion therapy: acute pulmonary oedema, hyperhydration, and decompensated cardiac insufficiency

• Severe renal insufficiency defined by the following criteria:

  • serum creatinine level > 353.6 µmol/L, or
  • creatinine level ≥ 3.0 times higher than the upper limit of normal (according to the KDIGO 2012 Clinical Practice Guideline), or
  • diuresis < 0.3 mL/kg/hr during ≥ 12 hrs (Acute Kidney Injury stage ≥ 3 according to the KDIGO 2012 Clinical Practice Guideline) without access to renal replacement therapy

• Unstable haemodynamic conditions (e.g., acute myocardial infarction, stroke, embolism, severe sepsis, shock) including acute shock (arterial serum lactate > 2.0 mmol/L)

• Severe liver insufficiency

• Haemophagocytic syndrome

• Pregnancy or lactation

• Receiving end-of-life care

• Severe hyperlipidaemia (serum cholesterol and/or triglycerides and/or LDL-C level at least 1.5 times higher than the upper limit of normal range)

• Pathologically elevated serum levels of any of the included electrolytes (sodium, potassium, magnesium, total calcium, chloride, inorganic phosphate)

• Participation in another interventional clinical trial within the previous 4 weeks

• Previous inclusion in the present study.