Michael, a 42 y.o. man is admitted to the med-surg floor with a diagnosis of acute pancreatitis. His BP is 136/76, pulse 96, Resps 22 and temp 101. His past history includes hyperlipidemia and alcohol abuse. The doctor prescribes an NG tube. Before inserting the tube, you explain the purpose to patient. Which of the following is a most accurate explanation?