Acute Pancreatitis

Acute inflammation of the pancreas that is subclassified by severity into:

The Glasgow Criteria are adverse prognostic factors:

  • Admission
    • Age >55
    • WCC >15 1,000/mm3
    • Glucose >10 mmol/L
    • AST >250 U/L
  • Within 48 hours
    • ↓ In Hct >10%
    • ↑ In urea >1.8 mmol/L
    • Calcium <2 mmol/L
    • PaO2 <60 mmHg

Epidemiology and Risk Factors

Pathophysiology

Aetiology

Precipitants include:

  • Biliary obstruction
    35-40%.
    • Gallstones
    • Malignancy
  • Drugs
    • Alcohol
      35%.
    • Antibiotics
      • Metronidazole
      • Nitrofurantoin
      • Erythromycin
      • Tetracyclines
      • Sulphonamides
    • Diuretics
      • Furosemide
      • Thiazides
    • Toxins
      • Methyl alcohol
      • Scorpion venom
      • Organophosphates
  • Metabolic
    • Hyperlipidaemia
    • Hypercalcaemia
      • Hyperparathyroidism
    • DKA
    • ESRD
  • Infections
    • Viral
      • HIV
      • EBV
      • Mumps
    • Bacteria
      • Mycoplasma
      • Legionella
      • Campylobacter
    • Parasites
      • Ascariasis
  • Immune
    • Polyarteritis nodosa
    • SLE
    • TTP
  • Pregnancy
  • Trauma
  • Iatrogenic
    • Postoperative

An enjoyable mnemonic for some of these causes is:

  • Idiopathic

  • Gall stones
  • Ethanol
  • Trauma

  • Steroids
  • Mumps
    And other viruses.
  • Autoimmune
  • Scorpions
  • Hyperlipidaemia
  • ERCP
  • Drugs

Clinical Manifestations

Diagnostic Approach and DDx

Investigations

Laboratory:

Amylase has been replaced by lipase, and has little current role in the diagnosis of pancreatitis.

  • Blood
    • Lipase
      90% sensitive and specific for acute disease.
      • Elevations from non-pancreatic causes are typically <3× ULN
    • LFTs
      For biliary obstruction.
    • Triglycerides
      >1000 mg/dL diagnostic of hypertriglyceridaemic pancreatitis, absent other causes.
    • Calcium

Imaging:

  • Contrast CT
    • Pancreatitis
      Loss of normal contrast enhancement.
    • Necrosis
  • Ultrasound
    • Usually limited by bowel gas
    • Cannot quantify necrosis
    • Provides assessment of biliary tree
      CBD dilation most important finding.
    • May provide guidance for needle aspiration

Management

Surgical management of pancreatitis is associated with very high mortality; supportive treatment is first line and and surgical management should only be resorted to if it is otherwise unavoidable.

Resuscitation:

  • C
    • Volume resuscitation
      • Aggressive volume resuscitation required for offsetting distributive shock and correcting hypovolaemia
      • >10mL/kg associated with ↑ ARDS and ↑ abdominal compartment syndrome
    • Haemodynamic support

Specific therapy:

Carbapenems have exceptional penetration into pancreatic tissue, and are effective against most culprit organisms.

  • Pharmacological
    • Antibiotics
      • Low threshold for IV antibiotics if suspecting infected collection
      • Prophylactic antimicrobials may have a role in severe disease
    • NSAIDs
      Appropriate post-ERCP in mild gallstone pancreatitis as analgesics and may ↓ severity.
    • Insulin/dextrose
      If hypertriglyceridaemia.
      • Goal is to promote anabolism
      • Effect achieved when enough insulin is provided such that the BSL does not rise in the face of dextrose infusion
  • Procedural
    • Open necrosectomy
      • Infected collections should be managed non-operatively for >4 weeks to allow fibrous walls and liquefaction to occur
      • Indications for surgery usually are other abdominal complication, e.g.:
        • Perforation
        • Bleeding
        • Mesenteric ischaemia
    • Needle aspiration
    • For gallstone pancreatitis:
      • Cholecystectomy
        Indicated due to high (up to 90%) rate of recurrence.
        • Mild cases can proceed immediately
        • More severe disease should be stabilised first
      • ERCP
        • ↓ Morbidity and mortality in mild gallstone pancreatitis
    • Plasmapheresis
      For hypertriglyceridaemia, with very little supportive evidence.

Supportive care:

Feeding:

  • Maintains gut mucosal barrier
  • Corrects nutritional deficiencies
    Many patients malnourished on presentation.
  • ↓ Risk of secondary infection of necrotic pancreatic tissue
  • G
    • Feeding
      • If non-intubated:
        • Oral diet as clinically tolerated
      • If intubated:
        • EN should be started once resuscitation finished
        • PN indicated only if EN fails or is contraindicated
          EN ↓ infection, organ failure, and mortality compared with PN.
        • NJ feeding may be preferable to NG to avoid ↑ pancreatic secretion
      • If hypertriglyceridaemic:
        • Zero-fat diet initially
        • Low-fat diet once triglycerides normal

Disposition:

Marginal and Ineffective Therapies

Prophylactic antifungal therapy is not recommended.

Various therapies aimed at generally ↓ pancreatic exocrine function are without evidence, and include:

  • Octreotide
  • Somatostatin
  • H2-antagonists
  • Atropine
  • Calcitonin
  • Glucagon
  • Fluorouracil

Interventions aimed to ↓ protease secretion are also without evidence, and include:

  • Aprotinin
  • Gabexate mesilate

Anaesthetic Considerations

Complications

  • Death
    5-10% mortality in severe disease.
  • B
    • ARDS
  • C
    • Shock
      • Distributive
      • Hypovolaemic
  • G
    • Abdominal compartment syndrome
    • Pancreatic cysts
      Do not merit surgical intervention unless:
      • Gastric outflow obstruction
      • Biliary obstruction
    • Infected necrosis
      • Usually arise at 10-14 days
      • Carbapenem or tazocin preferable for good solid organ penetration
    • Pancreatic abscess
      Infected collections are a major contributor to morbidity and mortality.
      • Usually arise at 4 weeks
      • Amenable to percutaneous drainage

Prognosis

Poor prognostic signs:

  • Pancreatic necrosis
    • Pancreatic head necrosis is as severe as whole pancreatic necrosis
    • Pancreatic tail necrosis usually has a good prognosis

Key Studies

  • WATERFALL (2022)
    • 249 of a planned 744 patients from Spain, France, Italy, and Mexico with acute pancreatitis
    • Aggressive vs moderate fluid resuscitation
      • Aggressive group:
        • 20mL/kg bolus
        • 3mL/kg/hr infusion for 48 hours
      • Moderate group:
        • 10mL/kg bolus
        • 1.5mL/kg/hr for 20 hours
    • Stopped early for harm in the aggressive group
      • ↑ Severity of pancreatitis

References

  1. de-Madaria E, Buxbaum JL, Maisonneuve P, et al. Aggressive or Moderate Fluid Resuscitation in Acute Pancreatitis. New England Journal of Medicine. 2022;387(11):989-1000.