Final answer:
The effectiveness of nasogastric tube suction and NPO in a patient with acute pancreatitis is best indicated by a decrease in abdominal pain, as these treatments are intended to limit pancreatic stimulation and allow the organ to rest.
Step-by-step explanation:
The information indicating the effectiveness of nasogastric (NG) tube suction and NPO (nil per os, or nothing by mouth) in a patient with acute pancreatitis is the decrease in abdominal pain. While all the provided options could suggest improvements, the direct impact of NG tube suction and NPO status would most likely be reflected through a reduction in abdominal pain since these interventions aim to reduce pancreatic stimulation and allow the pancreas to rest. Grey Turner sign resolution could be a result but is not directly related to NG tube efficacy. The presence of bowel sounds might indicate the return of gut motility but is not a direct indication of NG tube effectiveness. Normal electrolyte levels are important but they could be managed through other means like IV fluids. Therefore, a decrease in abdominal pain best indicates the effectiveness of the NG tube and NPO status.