Acute pancreatitis

• Acute pancreatitis is defined as an acute condition presenting with abdominal pain and is usually associated with raised pancreatic enzyme levels in the blood or urine as a result of pancreatic inflammation.
• Acute pancreatitis may recur.

Etiology and pathogenesis

• Gallstones
• Alcoholism
• Post ERCP
• Abdominal trauma
• Following biliary, upper GI or cardiothoracic surgery
• Ampullary tumors
• Drugs (corticosteroids, azathioprine, asparaginase, valproic acid, thiazides, oestrogens)
• Hyperparathyroidism
• Hypercalcaemia
• Pancreas divisum
• Autoimmune pancreatitis
• Hereditary pancreatitis
• Viral infections (mumps, coxsackie B)
• Malnutrition
• Scorpion bite
• Idiopathic

Pathogenesis

Activation of pancreatic pro enzymes (inactive enzymes)

Activation leads to auto digestion of the pancreas

Mechanisms of activation of pro enzymes

(1) Obstruction of the main pancreatic duct or terminal CBD

(a) Gall stones 

(b) Alcohol thickens ductal secretions.

    • Also increases duct permeability to enzymes

(2) Chemical injury of acinar cells

• Examples—thiazides, alcohol, triglyceride (> 1000mg/dl)

(3) Infectious injury of acinar cells

• Examples—CMV, mumps, coxsackie virus

(4) Mechanical injury of acinar cells

• Examples—seat belt trauma, posterior penetration of duodenal ulcer

(5) Metabolic activation of pro enzymes (e.g. hypercalcemia ischemia, shock)

Trypsin is important in the activation of pro enzymes.

(1) Proteases damage acinar cell structure.

(2) Lipases and phospholipases produce enzymatic fat necrosis.

(3) Elastases  damage vessel walls and produce hemorrhage.

(4) Activated enzymes also circulate in the blood.

Clinical features

• Sudden onset of upper abdominal pain which is referred to back. Pain may be relieved or reduced by leaning forward.
• Vomiting and high fever, tachypnoea with cyanosis.
• Tenderness, rebound tenderness, guarding, rigidity and abdominal distension, severe illness.
• There may be mild jaundice (due to cholangitis)
• Features of shock and dehydration.
• Oliguria
• Grey turner’s , Cullen’s sign
• Haematemesis/malaena due to duodenal necrosis, gastric erosions, decreased coagulability/ DIC

Investigations

• Serum amylase is very high or shows rising titre.
• Serum lipase more specific than amylase.
• LFT: Serum bilirubin, albumin, PT, alkaline phosphatase.
• Blood urea and serum creatinine
• Blood glucose
• Serum calcium level
• Arterial PO2 and PCO2 level to assess pulmonary insufficiency (or ARDS)
• Urinary lipase estimation
• Total count, haematocrit
• Peritoneal tap fluid shows high amylase and protein level
• Plain X-ray shows:

1. Sentinel  loop- of dilated proximal small bowel.
2. Distension of transverse colon with collapse of descending colon (colon cut off sign)
3. Air-fluid level in the duodenum.

• USG  and CT abdomen
• MRI
• MRCP
• CXR for effusion and ARDS

Sentinel  loop- of dilated proximal small bowel

Colon cut off sign

Treatment

• Mild attack:

I.V fluid resuscitation

Observation

• Severe attack:

Patient should be admitted to ICU

a. NPO until clinically improved

b. Aggressive fluid resuscitation with crystalloid solutions

c. Meperidine or fentanyl for pain

d. Nasogastric suction if vomiting severe

e. Oxygen

• If gallstones are the cause of an attack or if the patient has jaundice, cholangitis or dilated CBD, urgent ERCP should be done within 72 hrs of the onset of symptoms.
• Antibiotics are not indicated.
• Some evidence shows that prophylactic antibiotics ( i.v cefuroxime, imipenem or ciprofloxacin plus metronidazole) can prevent local and septic complication but the duration of use should not exceed 14 days.

Complications

a. Pancreatic necrosis
(1) Systemic signs occur earlier than usual.
(2) Higher fever than usual: sinus tachycardia
(3) Greater degree of neutrophilic leukocytosis
(4) Peripancreatic infections occur in 40% to 70% of cases.

b. Pancreatic pseudocyst (20%)
(1) Collection of digested pancreatic tissue around pancreas
(2) Abdominal mass with persistence of serum amylase longer than 10 days
(3) Treatment
(a) If  less than 5cm, observe and follow with CT scan.
                   Most resolve without surgical intervention.
(b) If greater than 5cm, percutaneous drainage with CT or ultrasound guidance

c. Pancreatic abscess

(1) Clinical and laboratory findings
(a) Abdominal pain
(b) High fever due to sepsis
     Usually gram-negative infections such as E. coli or Pseudomonas
(c) Neutrophilic leukocytosis
(d) Persistent hyperamylasemia
(2) Diagnosis
(a) CT scan shows multiple radiolucent bubbles in retroperitoneum
(b) CT-guided aspiration of abscess identifies organisms.
(3) Treatment
(a) Surgical drainage
(b) Imipenem- cilastin

 d. Pancreatic ascites
(1) Usually caused by leaking of a pseudocyst
(2) Peritoneal fluid has high amylase level.
(3) Usually resolves spontaneously

e. May develop acute respiratory distress syndrome or disseminated intravascular coagulation (DIC)

f. Pancreatic calcifications