The purpose of this study is to comparatively assess the potential antiinflammatory effects of intravenous lipid emulsions rich in omega 3 polyunsaturated fatty acids and olive oil versus intravenous lipid emulsions made exclusively with MCT and LCT on the evolution of patients with severe acute pancreatitis during the period in needing artificial nutrition support with total parenteral nutrition so unique.

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Inclusion Criteria:

• Diagnosis of acute pancreatitis: characteristic abdominal pain, serum amylase and / or lipase >= 3 times the upper limit of normal range, characteristic CT-scan
• Criteria of severity of acute pancreatitis diagnosed at <= 72 hours following admission: severity Index of Balthazar's CT-scan (with contrast) >= grade D, APACHE-II >= 8, C-reactive protein >= 150 mg/L
• Inability to initiate feeding (oral or with nutritional supplements) and / or enteral nutrition during the 5 days after the diagnosis and prediction of the indication of nil-by-mouth >= 5 days
• <= 3 mmol/L of triglycerides in the blood
• Men and women aged >= 18 years old
• Acceptance of informed consent

Exclusion Criteria:

• Known hipersensitivity to the fish, egg or soy proteins
• Lipid etiology
• > 3 mmol/L of triglycerides in the blood
• Severe hepatic impairment
• Severe renal insufficiency without dialysis or haemofiltration
• Serious disturbances of blood clotting
• Acute shock
• Infusion therapy general contraindications
• Clinical conditions of instability that must not be taken with parenteral nutrition
• Have other acute or chronic inflammatory diseases
• Status of severe immunosuppression: cytotoxic treatment in 15 days prior to inclusion and / or a disease that causes white blood cells levels <5000/mm3
• Treatment with steroids > 0.25 mg/kg/day of prednisone or equivalent doses of corticosteroids: as pre-treatment and / or during admission