Acute Pancreatitis in Adults

Background

• Acute pancreatitis is a rapid onset inflammatory process of the pancreas which may have local and systemic manifestations involving multiple organ systems.
• Severity can be assessed according to the Revised Atlanta classification from 2013.
  • Revised Atlanta classification assesses the following factors:
    • local complications such as pseudocyst, pancreatic necrosis.
    • organ failure such as acute respiratory failure (partial pressure of oxygen to fraction of inspired oxygen ratio < 400), shock (systolic blood pressure ≤ 90 mm Hg) and/or renal failure (creatinine ≥ 1.4 mg/dL).
  • Mild acute pancreatitis is defined as the absence of:
    • any extrapancreatic organ failure, including failure in respiratory, cardiovascular, and renal systems
    • local or systemic complications.
  • Moderately severe acute pancreatitis is defined as finding of complications, such as:
    • peripancreatic fluid collection or peripancreatic necrosis
    • systemic complications or organ failure that resolve within 48 hours.
  • Severe acute pancreatitis is defined as the presence of organ failure that persists > 48 hours. (Note that differentiation between moderate and severe pancreatitis can not be made until 48 hours after diagnosis.)
• The most common causes of acute pancreatitis are gallstones and significant alcohol use. Alcoholic pancreatitis usual occurs in the setting of chronic heavy consumption, but may present after acute substantial alcohol intake..
• Other causes of acute pancreatitis include drug-induced, hypertriglyceridemia, genetic predisposition, trauma including post-endoscopic retrograde cholangiopancreatography (ERCP), infectious, and idiopathic.
• Prevention strategies are available for certain causes of acute pancreatitis including gallstones and hypertriglyceridemia.

Evaluation

• Establishing a diagnosis of acute pancreatitis:
  • Typical features of acute pancreatitis include:
    • acute epigastric or left upper quadrant abdominal pain
    • pain which may worsen in the supine position or radiate to the back
    • associated nausea and vomiting
  • Obtain serum amylase and lipase if acute pancreatitis is suspected.
  • Diagnose acute pancreatitis based on Revised Atlanta Classification if ≥ 2 of:
    • abdominal pain consistent with pancreatitis
    • serum amylase and/or lipase > 3 times upper limit of normal
    • characteristic findings from abdominal imaging
  • If the diagnosis is uncertain or there is failure to improve clinically within 48-72 hours obtain contrast-enhanced computed tomography (CECT) or magnetic resonance imaging (MRI) (Strong recommendation) to confirm diagnosis and assess for complications such as fluid collections of necrosis.
• Additional testing
  • Obtain blood urea nitrogen (BUN), creatinine, liver function tests, albumin, glucose, lactate dehydrogenase (LDH), white blood cell count, hematocrit, calcium, and arterial blood gases to identify related comorbidities and complications, and assess severity.
  • Obtain serum triglyceride level if no history of gallstones or significant alcohol use (Weak recommendation).
  • Imaging in patients with acute pancreatitis:
    • Obtain abdominal ultrasound in all patients with acute pancreatitis (Strong recommendation) to assess for gallstones and biliary sludge/microlithiasis.
    • Consider endoscopic ultrasound (EUS) or magnetic resonance cholangiopancreatography (MRCP) if choledocholithiasis is highly suspected in the absence of cholangitis and/or jaundice (Weak recommendation).
• If infected necrosis is suspected, either perform a CT-guided fine-needle aspiration for Gram stain and culture and provide empiric antibiotics (Strong recommendation).
• Perform endoscopic retrograde cholangiopancreatography (ERCP) within 24 hours if there is concurrent acute cholangitis with obstruction (Strong recommendation). ERCP is not needed if there is no evidence of ongoing biliary obstruction (Strong recommendation).
• Consider MRI/MRCP and/or EUS study to evaluate for pancreatic or extrapancreatic tumor as possible cause of acute pancreatitis in patients > 40 years old (Weak recommendation).
• Consider alternative causes of acute abdominal pain such as gall stones, kidney stones, or appendicitis.

Management

• Treatment setting:
  • Most episodes of acute pancreatitis are mild, and may need only brief admission to a general medicine unit
  • Admit the patient to an intensive care unit if there is organ failure (Strong recommendation), or other signs and symptoms of a severe disease including hypoxia, tachypnea, delirium, significant gastrointestinal bleeding, hypotension, or systemic inflammatory response syndrome (SIRS).
• Provide aggressive fluid rescucitation (such as lactated Ringer's solution 250-500 mL/hour) (Strong recommendation)
  • Reassess fluid requirements at frequent intervals within 6 hours of admission and for the next 24-48 hours to achieve decrease in blood urea nitrogen (Strong recommendation), with dilutionary reduction in hematocrit a second marker to consider following.
  • Adequate fluid resuscitation should maintain urine output ≥ 0.5 mL/kg/hour without renal failure.
• Provide analgesia, which is critically important, but there is insufficient evidence to suggest optimal drug selection.
• Ensure adequate nutrition.
  • In mild acute pancreatitis, consider starting oral feeding as soon as the patient is free from nausea and vomiting (Weak recommendation). Patients do not need to be completely pain-free to resume feeding.
  • In severe acute pancreatitis, enteral nutrition is preferred over parenteral nutrition (Strong recommendation) and consider initiating within 72 hours if possible.
• In severe acute pancreatitis:
  • Do not give prophylactic antibiotics, including for patients with sterile necrosis (Strong recommendation).
  • Prescribe antibiotics for extrapancreatic infection (Strong recommendation).
  • Insulin may be required temporarily.
• Perform endoscopic retrograde cholangiopancreatography (ERCP) within 24 hours for patients with gallstone pancreatitis with cholangitis and within 72 hours in patients with high suspicion of persistent common bile duct stone (Strong recommendation).
• Do not perform drainage or debridement for asymptomatic pancreatic pseudocysts or necrosis (regardless of size or location) (Strong recommendation).
• If infected necrosis is suspected, obtain a computed tomography (CT)-guided fine-needle aspiration for Gram stain and culture (consider fungal stain and culture as well) to guide antibiotic selection, and begin empiric antibiotics with 1 of the following suggested regimens for a total of 14 days (Strong recommendation):
  • imipenem-cilastatin 500 mg IV every 6 hours or 1,000 mg IV every 8 hours
  • meropenem 1,000 mg IV every 8 hours
  • piperacillin-tazobactam 3.375 g IV every 6 hours
  • doripenem 500 mg IV every 8 hours (not available in the United States)
  • metronidazole 500 mg IV every 8 hours or 1,500 mg IV every 24 hours plus one of
    • cefepime 2,000 mg IV every 8-12 hours
    • ceftazidime 2,000 mg IV every 8 hours
    • ciprofloxacin 400 mg IV every 12 hours
    • levofloxacin 750 mg IV every 24 hours
• If performing necrosectomy for symptomatic infected necrosis, use minimally invasive methods if feasible (Strong recommendation), beginning with endoscopic (EUS guided) therapy where availible, then considered percutaneous drainage as second line and reserving minimally invasive or open surgery if other options are not availible.
• Monitor for systemic complications, especially pulmonary, cardiovascular and renal complications.
• In patients with gallstones, perform cholecystectomy (Strong recommendation).
  • In mild cases, perform before discharge.
  • In severe cases perform after inflammation and fluid collections resolve or stabilize, which may or may not occur before discharge.
  • Biliary sludge and microlithiasis have been reported to be associated with recurrent pancreatitis.
• To decrease risk of recurrent acute pancreatitis, treat alcohol abuse disorders and triglyceride levels > 1,000 mg/dL (11.3 mmol/L).