All patients will commence enteral feeding via a nasogastric or orogastric tube; allocation to either Oxepa or Pulmocare/Jevity (control group) will be determined by randomization code. Patients will be prescribed to receive a daily amount of enteral formula that provides at least 80% of their energy; the latter will be calculated every 48 to 72 hours by Indirect Calorimetric (IC) measurement of Resting Energy Expenditure (REE). Tolerance of EN will be assessed by measurement of Gastric Residual Volume (GRV) every 8 hrs and the mode of feeding will be modified accordingly.