pancreatitis%20-%20acute
PANCREATITIS - ACUTE
Acute pancreatitis is inflammation of the pancreas that occurs suddenly.
Abdominal pain is the most prominent symptom of acute pancreatitis.
It is diagnosed by at least two of the following: Characteristic abdominal pain, serum lipase and/or amylase levels ≥3 times the upper limit of normal and characteristic abdominal imaging findings.
Mild acute pancreatitis does not have any organ failure or local or systemic complication.
Moderately severe acute pancreatitis has the presence of local or systemic complication and/or transient organ failure in <48 hours.
Severe acute pancreatitis has single or multiple organ failure persistent in >48 hours.

Pancreatitis%20-%20acute Diagnosis

Diagnosis

Acute pancreatitis is diagnosed by at least 2 of the following:  

  • Characteristic abdominal pain
  • Serum lipase and/or amylase levels ≥3x the upper limit of normal
  • Characteristic abdominal imaging findings

Idiopathic Pancreatitis

  • Pancreatitis without established etiology after initial lab work-up and imaging tests  
  • Perform at least 2 ultrasound exams to exclude a biliary etiology, and a magnetic resonance cholangiopancreatography (MRCP) and/or endoscopic ultrasound for prevention of recurrent pancreatitis

Classification

Classification Systems of Acute Pancreatitis

2012 Revised Atlanta Criteria 

  • Mild: Without organ failure or local or systemic complication
  • Moderately severe: Presence of local or systemic complication and/or transient organ failure <48 hours
  • Severe: Single or multiple organ failure persistent >48 hours

Determinant-based Classification

  • Mild: Without organ failure and (peri)pancreatic necrosis
  • Moderate: Presence of transient organ failure and/or sterile (peri)pancreatic necrosis
  • Severe: Persistent organ failure or infected (peri)pancreatic necrosis
  • Critical: Persistent organ failure and infected (peri)pancreatic necrosis

Assessment

Initial Assessment

Predicting the severity of acute pancreatitis during the early part of disease is warranted to minimize complications and to obtain the most benefit from treatment

  • All patients should undergo assessment of the following parameters immediately upon admission:
    • Clinical evaluation, with emphasis on the presence of organ failure, or any cardiovascular, respiratory or renal dysfunction
    • Determination of body mass index (BMI), Acute Physiology and Chronic Health Evaluation (APACHE) II score
      • APACHE score should be calculated on admission and every day for the 1st 72 hours following admission
      • The Bedside Index of Severity of Acute Pancreatitis (BISAP) is a recently developed simple prognostic scoring system for predicting severe acute pancreatitis with similar accuracy to the APACHE II score for predicting mortality; criteria include BUN >8.9 mmol/L, impaired mental status, SIRS, age >60 years old, pleural effusion on radiography
    • Chest X-ray should be obtained
  • Clinical exam within the 1st 24 hours of admission is specific but lacks specificity in determining severity and therefore should be supported by objective measures
  • A severe attack is likely in patients who have the following features:
    • Clinical impression of severity
    • BMI >30, pleural effusion
    • APACHE II score >8

24 Hours After Admission

  • Clinical assessment and documentation of organ failure should be repeated
    • APACHE II score to assess the worst values in the 1st 24 hours
    • CRP may be useful based on time of onset of symptoms
    • Glasgow score may be applied
  • A severe attack is likely in patients who have the following features:
    • Clinical impression of severity
    • APACHE II score >8
    • Glasgow score ≥3
    • CRP >150 mg/L
    • Persisting organ failure

48 Hours After Admission

  • Clinical state, Glasgow score and CRP all contribute to the assessment of severity
  • Contrast-enhanced CT may also be used to assist in staging severity
  • A severe attack is likely in patients who have the following features:
    • Clinical impression of severity
    • Apache II score >8
    • Glasgow score ≥3
    • CRP >150 mg/L
    • Persisting organ failure for >48 hours
    • Multiple or progressive organ failure

Physical Examination

  • Physical findings will depend on the severity of an acute pancreatitis attack

Vital Signs

  • Blood pressure may increase transiently, then decrease with third-space fluid losses
  • Tachycardia, tachypnea and fever are usually present

Abdominal Findings

  • Patient may exhibit guarding and tenderness especially in the upper abdomen
  • Bowel sounds are often decreased
  • Ecchymoses on the flanks or in the periumbilical area may be seen

Other Findings

  • Dyspnea which may be secondary to congestive heart failure, pleural effusion or atelectasis
  • Shallow respirations with limited diaphragmatic excursion
  • Mental status changes eg hallucinations, disorientation and coma
  • Physical exam may reveal findings related to the underlying cause of pancreatitis
    • Hepatomegaly and spider angiomas in alcoholic patients
    • Xanthomas and lipemia retinalis in hyperlipidemic patients

Laboratory Tests

Serum Amylase

  • Serum amylase is frequently requested because it is affordable and readily available
  • Serum amylase testing is not 100% sensitive or specific
  • Nonpancreatic diseases eg tumors, salivary gland diseases and renal insufficiency may also cause hyperamylasemia
  • A level 3x the upper limit of normal (ULN) is commonly set as being suggestive of acute pancreatitis, but this level is still not specific for the disease
  • Hyperamylasemia supports a diagnosis of acute pancreatitis, but cannot be used to confirm it
  • The degree of enzyme elevation does not correlate with disease severity

Serum Lipase

  • Some authorities maintain that serum lipase is a more specific and more reliable test than serum amylase because of its higher sensitivity and greater diagnostic window; also, nearly all lipase in the body originates from the pancreas, in contrast to amylase which may also be secreted by the salivary glands
    • Should be done in all patients in whom acute pancreatitis is suspected 
  • The enzyme is elevated starting on the 1st day of illness and remains elevated longer than serum amylase; cut-off value is 3x ULN
  • Sensitivity of serum lipase in diagnosing acute pancreatitis is considered similar to that of serum amylase
  • Like serum amylase, the degree of enzyme elevation does not correlate with disease severity
  • Certain nonpancreatic diseases may give rise to serum lipase elevations eg renal disease, acute cholecystitis, appendicitis, bowel obstruction, chronic pancreatitis

Other Tests

  • C-reactive protein (CRP) is a marker of inflammation and necrosis
    • Elevated levels (≥150 mg/L) at 48-72 hours after onset of disease are useful in disease stratification and determining disease severity
  • Complete blood count (CBC) usually shows leukopenia; hematocrit of >44% is a risk factor of pancreatic necrosis
  • Serum glucose and glucagon levels are frequently elevated
  • Liver function tests (LFTs), eg alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and bilirubin are often high, especially in gallstone pancreatitis
  • A serum triglyceride should be obtained if gallstones or a history of significant alcohol use is absent
    • If >1000 mg/dL, may be considered an etiology of acute pancreatitis
  • A serum procalcitonin level of ≥3.8 ng/mL within 96 hours after symptom onset indicates pancreatic necrosis while a blood urea nitrogen (BUN) level of >20 mg/dL is an independent predictor of mortality 

Imaging

Abdominal and Chest X-rays

  • Abdominal film may be used to exclude other causes of abdominal pain
    • May be normal in mild disease but in more severe disease may assist in assessing etiology or severity of pancreatitis
  • Gallstones and pancreatic stones may also be visualized on abdominal X-rays
  • Chest X-rays may reveal atelectasis, pulmonary infiltrates, pleural effusion or an elevated hemidiaphragm

Abdominal Ultrasound (US)

  • US should be examined at baseline (on admission or within the 1st 48 hours) in all patients with possible acute pancreatitis
  • US can demonstrate morphological changes in the pancreas 24-48 hours after disease onset and is useful in detecting presence or absence of biliary disease, ie gallstones and/or common bile duct stones
  • US cannot be used to evaluate severity of disease
  • Bowel gas, however, often precludes a good view of the pancreas

Abdominal Computed Tomography (CT) Scan

  • CT scan is not mandatory upon initial presentation of the patient, unless diagnosis is uncertain or there are important differential diagnoses that need to be excluded, eg mesenteric ischemia or secondary perforation peritonitis
    • Patients who will likely benefit from CT scanning are those with persisting organ failure, new onset of organ failure or new complication and patients with persistent pain and signs of sepsis
  • Contrast-enhanced CT (CECT) scan is used chiefly to establish the diagnosis and severity of acute pancreatitis, to search for complications of acute pancreatitis and to exclude other serious intra-abdominal conditions
    • Optimal timing is 72-96 hours after symptom onset in patients with severe acute pancreatitis 
  • The test is not useful for detecting gallstones

Magnetic Resonance Imaging (MRI)

  • Detects pancreatic necrosis as well as CT scan, but is better at detecting gallstones
  • An advantage of MRI over CT scan may be the lesser toxicity of gadolinium compared to contrast material
    • Preferred over CECT scan in young or pregnant patients to minimize exposure to radiation, patients with iodinated contrast allergy and in those with renal impairment or insufficiency 

Magnetic Resonance Cholangiopancreatography (MRCP) 

  • Recommended to check for occult common bile duct stones in patients with unknown etiology, ie if liver enzymes are elevated suggesting biliary obstruction and the common bile duct is either normal or not adequately visualized on ultrasound

Endoscopic Retrograde Cholangiopancreatography (ERCP)

  • ERCP only has role in severe acute pancreatitis when there is a confirmed acute biliary pancreatitis with concomitant cholangitis
    • In these cases, ERCP is done to remove common duct stones within 24 hours of admission

Prognosis

  • Prognostic factors that help in determining disease activity include presence of systemic inflammatory response syndrome (SIRS), level of hematocrit, BUN, or creatinine
    • An increase in the number of SIRS criteria during the 1st 24 hours of hospitalization as well as increase in the values of hematocrit, BUN, or creatinine elevates the risk of organ failure, pancreatic necrosis, and mortality
  • Persistent organ failure and high mortality are associated with severe acute pancreatitis thus the need for an ICU admission 
    • Risk of mortality is high in patients with persistent organ failure and infected necrosis
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