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Pancreatitis: A Complete Clinical Guide for the Duty Doctor in Gastroenterology

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1. PATHOPHYSIOLOGY - KNOW YOUR ENEMY

1. Inciting event (gallstone obstruction, alcohol, drugs, etc.) causes cellular injury
2. Lysosomal (cathepsin B) and zymogen (trypsinogen) contents colocalize within the acinar cell
3. Trypsinogen is activated to trypsin - which then activates all other digestive enzymes (autodigestion)
4. Sustained rise in cytosolic Ca²+ activates NF-kB - triggering cytokine/chemokine release
5. Macrophage and neutrophil recruitment magnifies local damage
6. SIRS, organ failure, sepsis, and shock follow in severe cases
7. Bacteremia via translocation of gut organisms completes the picture in infected necrosis

• Schwartz's Principles of Surgery, 11e

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2. ETIOLOGY (I GET SMASHED - Classic Mnemonic)

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3. DIAGNOSIS IN CASUALTY

Diagnostic Criteria (2 of 3 required)

1. Characteristic abdominal pain - severe, steady, epigastric/periumbilical, radiates to the back, worse supine, better leaning forward
2. Serum lipase or amylase > 3x upper limit of normal - lipase is preferred (more sensitive and specific; stays elevated longer)
3. Characteristic findings on cross-sectional imaging (CT/MRI)

Amylase >3x ULN is threshold - levels may be normal in alcoholic pancreatitis or hypertriglyceridemia. Always order lipase.

Investigations to Order at Casualty Triage

• Serum lipase (preferred) + amylase
• CBC, CRP (baseline - CRP >150 mg/dL at 48h predicts severe disease)
• BMP: BUN, creatinine, electrolytes, glucose, calcium
• LFTs (ALT >3x ULN = biliary etiology with ~95% PPV)
• Serum triglycerides
• ABG if any respiratory distress

• Abdominal ultrasound - mandatory in ALL patients to look for gallstones/biliary dilation (sensitivity 95% for gallstones). Pancreas itself is often not well visualized due to bowel gas.
• CT scan (contrast-enhanced, portal venous phase) - NOT routine at presentation. Indications:
  • Diagnostic uncertainty
  • Failure to improve after 48-72h conservative management
  • Clinical deterioration / suspected complications
  • CTSI scoring for severity

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4. SEVERITY ASSESSMENT

2012 Revised Atlanta Classification

Ranson's Criteria (11 parameters)

BISAP Score (Bedside Index for Severity in Acute Pancreatitis)

SIRS Criteria (Recommended for Real-Time Monitoring)

• Temperature <36°C or >38°C
• HR >90 bpm
• RR >20 or PaCO2 <32 mmHg
• WBC <4000 or >12,000 or >10% bands

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5. EMERGENCY MANAGEMENT - THE FIRST 24 HOURS

5A. Fluid Resuscitation (The Most Critical Intervention)

"The most important treatment intervention for acute pancreatitis is early, intravenous fluid resuscitation to prevent systemic complications." - Harrison's Principles of Internal Medicine (22e)

• Lactated Ringer's (LR) is the preferred fluid over normal saline. LR is more physiologic and has demonstrated anti-inflammatory properties (prevents acidosis, reduces SIRS). Supported by RCT evidence.
• Avoid normal saline as primary resuscitation fluid (hyperchloremic acidosis risk).

• Goal-directed: 250-500 mL/hour initially in first few hours
• Monitor response with: urine output (goal >0.5-1 mL/kg/hour), HR normalization, BUN trend
• Avoid over-resuscitation - can worsen abdominal compartment syndrome, respiratory failure. Proponents of aggressive therapy (5-10 mL/kg/hr) must be balanced against these risks.
• Reassess every 4-6 hours and taper rate as patient improves.

• Hourly urine output
• BUN (rising BUN = inadequate resuscitation)
• Hematocrit (should decrease with adequate fluids if hemoconcentrated)

5B. Pain Management

• Route: IV, at least initially, due to unpredictable absorption and vomiting
• Agents: No single agent is definitively superior. Options:
  • NSAIDs (ketorolac 30 mg IV) - good first-line, anti-inflammatory effect
  • Opioids when NSAIDs insufficient - hydromorphone or fentanyl preferred. No evidence that morphine is harmful despite theoretical concern about sphincter of Oddi spasm.
  • Patient-controlled analgesia (PCA) - appropriate for severe/prolonged cases
• Opioids may promote ileus - use at lowest effective dose.

5C. NPO and Nasogastric Tube

• Make patient NPO initially to minimize exocrine stimulation
• NGT only if patient has intractable vomiting or ileus causing distension - not routine

5D. Antiemetics

• Metoclopramide, ondansetron, or promethazine for nausea/vomiting

5E. Monitoring Setup

• IV access x2, continuous pulse oximetry, cardiac monitoring if hemodynamically unstable
• Strict input-output chart
• Blood glucose monitoring every 4-6h (risk of hyperglycemia)
• Serial abdominal exams

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6. HOSPITAL MANAGEMENT

6A. Ward vs. ICU Decision

• Persistent organ failure (Severe Atlanta)
• BISAP ≥3 or Ranson ≥3
• SIRS criteria met at presentation or 48h
• Hemodynamic instability requiring vasopressors
• Respiratory failure (SpO2 <95% on room air)
• Necrotizing pancreatitis on CT

6B. Nutrition - Critical and Often Mismanaged

• Standard polymeric formulas are adequate - no evidence for elemental or immune-enhancing formulas over standard
• Enteral nutrition maintains gut barrier integrity, reduces bacterial translocation, and attenuates inflammatory response

6C. Antibiotics

1. Documented infected pancreatic necrosis (positive culture from CT-guided FNA or interventional drain, or gas in necrosis on CT)
2. Ascending cholangitis (Charcot's triad: fever + jaundice + RUQ pain)
3. Other confirmed extra-pancreatic infections (UTI, pneumonia, bacteremia)

• Carbapenems (meropenem, imipenem) - good pancreatic penetration, covers gram-negative enteric organisms which are most common (E. coli, Klebsiella, Enterococcus)
• Alternatives: ciprofloxacin + metronidazole, or piperacillin-tazobactam

6D. Special Considerations by Etiology

• All patients should have cholecystectomy before discharge (or within 2-4 weeks of mild AP) to prevent recurrence (~50% recurrence without it)
• Do NOT perform cholecystectomy during acute attack

• Emergency ERCP (within 24h): Acute cholangitis concurrent with AP
• Urgent ERCP (within 48-72h): Persistent biliary obstruction without cholangitis (jaundice, rising bilirubin)
• NOT indicated in uncomplicated gallstone pancreatitis - the offending stone usually passes spontaneously

• Insulin infusion (lowers TG rapidly)
• Heparin (activates lipoprotein lipase)
• Plasmapheresis in refractory severe cases
• Long-term: fibrate therapy, dietary restriction

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7. COMPLICATIONS AND THEIR MANAGEMENT

Local Complications (Atlanta 2012 Classification)

Management of Necrotizing Pancreatitis

• Sterile necrosis: Managed conservatively - no intervention, no prophylactic antibiotics. The majority resolve.
• Infected necrosis: Diagnosed by CT showing gas in necrosis, or positive culture from drain/FNA. Requires drainage + antibiotics.

1. Antibiotics (carbapenems)
2. Delay intervention to allow walling-off (ideally ≥4 weeks from onset)
3. Percutaneous catheter drainage (PCD) as first-line - resolves ~1/3 to half of cases without further intervention
4. Minimally invasive drainage if PCD fails:

• Video-assisted retroperitoneal debridement (VARD)
• Endoscopic ultrasound-guided transmural drainage/necrosectomy

1. Open surgical necrosectomy - last resort, highest morbidity. Reserved for failure of all minimally invasive approaches.

Pseudocyst

• Fluid collection >4 weeks with defined wall, no necrosis
• Asymptomatic pseudocysts - observe, most resolve spontaneously
• Symptomatic (pain, early satiety, obstruction, infection) - endoscopic transmural drainage preferred (EUS-guided cystogastrostomy), or percutaneous drainage

Systemic Complications

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8. CHRONIC PANCREATITIS - KEY POINTS FOR WARD CALLS

• Pain is chronic, progressive, postprandial, epigastric radiating to back
• Serum amylase/lipase may be normal in established chronic pancreatitis (burnt-out exocrine function)
• Look for: steatorrhea, weight loss, diabetes mellitus ("pancreatic diabetes")
• CT findings: pancreatic calcifications, ductal dilation, parenchymal atrophy
• Exocrine insufficiency: Treat with pancreatic enzyme replacement therapy (PERT) - lipase ≥40,000-50,000 IU per meal, with acid suppression (PPI)
• Pain management: Stepwise - paracetamol > NSAIDs > tramadol > opioids; adjuncts include pregabalin, celiac plexus block
• Endoscopic/surgical: ERCP for ductal stones/strictures; Puestow procedure (lateral pancreaticojejunostomy) for dilated duct with pain

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9. QUICK REFERENCE - CASUALTY CHECKLIST

ACUTE PANCREATITIS - CASUALTY PROTOCOL

□ IV access x2 + bloods: lipase, amylase, CBC, CMP, LFTs, CRP, triglycerides, ABG
□ Abdominal USS (all patients - gallstones)
□ Start IV Lactated Ringer's 250-500 mL/hr, titrate to UO >0.5 mL/kg/hr
□ NPO + antiemetics
□ IV analgesia (ketorolac ± opioid)
□ Urinary catheter for strict I/O monitoring
□ Calculate BISAP score
□ If BISAP ≥3 or SIRS: Consider ICU/HDU transfer
□ CT with contrast ONLY IF: diagnostic uncertainty, clinical deterioration at 48-72h
□ NO prophylactic antibiotics
□ Reassess at 48h: SIRS status, BUN trend, fluid balance, organ function
□ Nutrition: Start oral/NG feeds as soon as tolerated; do NOT wait for amylase normalisation
□ If gallstone etiology: plan cholecystectomy before discharge
□ If cholangitis: URGENT ERCP within 24h

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10. CURRENT GUIDELINES - 2024/2025 UPDATES

• LR preferred over NS for fluid resuscitation
• Enteral > parenteral nutrition - start early
• No prophylactic antibiotics in AP or necrotizing pancreatitis
• Step-up approach for infected necrosis with delayed (≥4 weeks) intervention
• Cholecystectomy during index admission or within 2-4 weeks for biliary pancreatitis
• ERCP only for cholangitis or persistent biliary obstruction

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• Mild AP (interstitial edematous): <1% mortality
• Moderate AP: ~3-8%
• Severe AP (organ failure >48h): 20-40%
• Infected necrotizing pancreatitis: up to 30-50%