Timing of Target Enteral Feeding in the Mechanically Ventilated Patient

Inclusion Criteria: Patients will be eligible for inclusion in the study if they meet the following criteria: * Mechanical ventilation expected to last at least 72 hours. * Presence of, or primary physician's intent to place, an enteral feeding tube and begin enteral feeds. Exclusion Criteria: * More than 48 hours elapsed since both inclusion criteria met. * Patient, legal representative, or physician refuses consent or is unavailable to provide consent. * Patient, legal representative, or physician not committed to full support (Exception: A patient will not be excluded if he/she would receive all supportive care except for attempts at resuscitation from cardiac arrest). * Presence of malignant or irreversible condition and estimated 28 day mortality greater than 50%. * Severe or refractory shock. * Moribund patients not expected to survive 24 hours from start of enteral feeding (as determined by primary medical team). * Child-Pugh score greater than 10. * Presence of partial or complete mechanical bowel obstruction, or ischemia, or infarction. * Current TPN use or intent to use TPN within 7 days. * Severe malnutrition with BMI less than 18.5 and/or loss of more than 30% total body weight in the previous 6 months. * Neuromuscular disease impairing the ability to ventilate spontaneously. * Laparotomy expected within 7 days. * Unable to raise head of bed 45°. * greater than 30% total body surface area burns. * Absence of GI tract/short bowel syndrome - defined as entire length of small bowel totaling 4 feet or less. * Presence of high-output (\> 500 cc/day) enterocutaneous fistula. * Age less than 13 years * Allergy to enteral formula