A client is admitted with acute pancreatitis. Which intervention is most important initially?

Acute pancreatitis is inflammation of the pancreas with severe abdominal pain (epigastric, radiating to back), nausea, vomiting, elevated amylase and lipase. Most common causes: gallstones and alcohol use. Severe cases can progress to systemic inflammatory response, ARDS, organ failure, death. Initial management: (1) NPO to rest the pancreas and reduce pancreatic enzyme secretion; (2) Aggressive IV fluid resuscitation — pancreatitis causes massive third-spacing of fluid (lactated Ringer's preferred); monitor urine output, vital signs, mental status; (3) Pain management — typically opioids (hydromorphone or morphine; some sources still avoid morphine due to theoretical concerns about sphincter of Oddi spasm, though evidence is weak); (4) Antiemetics; (5) Monitor electrolytes — hypocalcemia is common (positive Chvostek's or Trousseau's signs); also hypomagnesemia, hyperglycemia (transient or new diabetes); (6) Monitor for complications: pseudocyst, abscess, necrosis, ARDS, AKI, shock, DIC; (7) Identify and treat underlying cause; (8) Nutrition — enteral nutrition (via jejunal tube) preferred over TPN in moderate-severe cases as soon as possible; resume oral intake gradually as symptoms resolve.