The purpose of the study is to investigate the efficacy and safety of a convenient 3-chamber-bag containing aminoacids, glucose and lipid emulsion (LCT/MCT 20%) compared to a conventionally compounded monobag for parenteral nutrition.

Inclusion: •Patients considered for elective open abdominal surgery

• Male and female patients ≥18 and <85 years of age
• Indication for total parenteral nutrition therapy: for 6 consecutive days
• NRS ≥3
• Ability and willingness to give voluntary consent to participate in the study, following a full explanation of the nature and purpose of the study, by signing the informed consent form approved by the Institutional Review Board (IRB) prior to all evaluations, and to comply with the requirements of the study

Exclusion: Major criteria:

• Body weight < 50 kg or > 70 kg
• Laparoscopic surgery
• Seriously ill patients in need of high energy nutrition support (i. e. > 2100 Kcal/day)
• Hepatic surgery
• Surgery with estimated blood loss >1000ml
• Participation in a clinical study with an investigational drug or an investigational medical device within one month prior to the start of study
• Receiving regular parenteral nutrition within 7 days before the onset of study
• General contraindications for parenteral nutrition (acidosis of various geneses, untreated disorders of electrolyte and fluid balance, hyperhydration, acute pulmonary edema, inadequate cellular oxygen supply)
• General contraindications for infusion therapy such as acute pulmonary oedema, hyperhydration and decompensated cardiac insufficiency, acute stroke
• Known hypersensitivity to egg-, soy-, and peanut proteins or any of the ingredients