The purpose of this pilot study is to assess the efficacy, safety and tolerance profile of the enteral feeding product VITAL AF (a semi-elemental, high protein, and high omega-3 fish oil) when compared to Osmolite 1.2, a standard feeding product in critically ill and/or post surgical patients in the intensive care unit (ICU). If enough patients are recruited, inferences about impact on outcomes may also be drawn.

Inclusion Criteria:

• Subject requires enteral tube feeding as sole source of nourishment
• Subject, or subject's legally acceptable representative (LAR), has provided voluntarily and informed consent form, as deemed appropriate and approved by the Columbia University Medical Center Institutional Review Board
• Subject is ≥ 18 years of age
• Subject is male or non-pregnant female at least six weeks postpartum and non-lactating females of childbearing potential will be required to confirm non-pregnancy status with a pregnancy test at screening
• Subject has an initial APACHE II score less than or equal to 24

Exclusion Criteria:

• Subject requires parenteral nutrition
• Subject is acutely impacted or constipated
• Subject has intestinal obstruction
• Subject is too hemodynamically unstable for enteral feeding
• Subject has an allergy or intolerance to any ingredient in the study product by documentation or verbal report by subject or subject's LAR
• Subject is participating in a non-Abbott approved concomitant trial
• Subject has gastrointestinal disease, including acute pancreatitis, active gastrointestinal bleeding, acute inflammatory bowel disease, or has undergone intestinal surgery within the past month