Necrotizing pancreatitis: Diagnose, treat, consult

MANAGING COMPLICATIONS OF PANCREATIC NECROSIS

Necrotizing pancreatitis is a defining complication of acute pancreatitis, and its presence alone indicates greater severity. However, superimposed complications may further worsen outcomes.

Infected pancreatic necrosis

Infection occurs in approximately 20% of patients with necrotizing pancreatitis and confers a mortality rate of 20% to 50%.¹⁹ Infected pancreatic necrosis occurs when gut organisms translocate into the nearby necrotic pancreatic and peripancreatic tissue. The most commonly identified organisms include Escherichia coli and Enterococcus species.²⁰

This complication usually manifests 2 to 4 weeks after symptom onset; earlier onset is uncommon to rare. It should be considered when the systemic inflammatory response syndrome persists or recurs after 10 days to 2 weeks. Systemic inflammatory response syndrome is also common in sterile necrotizing pancreatitis and sometimes in interstitial pancreatitis, particularly during the first week. However, its sudden appearance or resurgence, high spiking fevers, or worsening organ failure in the later phase (2–4 weeks) of pancreatitis should heighten suspicion of infected pancreatic necrosis.

Imaging may also help diagnose infection, and the presence of gas within a collection or region of necrosis is highly specific. However, the presence of gas is not completely sensitive for infection, as it is seen in only 12% to 22% of infected cases.

Before minimally invasive techniques became available, the diagnosis of infected pancreatic necrosis was confirmed by percutaneous CT-guided aspiration of the necrotic mass or collection for Gram stain and culture.

Antibiotic therapy is indicated in confirmed or suspected cases of infected pancreatic necrosis. Antibiotics with gram-negative coverage and appropriate penetration such as carbapenems, metronidazole, fluoroquinolones, and selected cephalosporins are most commonly used. Meropenem is the antibiotic of choice at our institution.

CT-guided fine-needle aspiration is often done if suspected infected pancreatic necrosis fails to respond to empiric antibiotic therapy.

Debridement or drainage. Generally, the diagnosis or suspicion of infected pancreatic necrosis (suggestive signs are high fever, elevated white blood cell count, and sepsis) warrants an intervention to debride or drain infected pancreatic tissue and control sepsis.²¹

While source control is integral to the successful treatment of infected pancreatic necrosis, antibiotic therapy may provide a bridge to intervention for critically ill patients by suppressing bacteremia and subsequent sepsis. A 2013 meta-analysis found that 324 of 409 patients with suspected infected pancreatic necrosis were successfully stabilized with antibiotic treatment.^21,22 The trend toward conservative management and promising outcomes with antibiotic therapy alone or with minimally invasive techniques has lessened the need for diagnostic CT-guided fine-needle aspiration.

Hemorrhage

Spontaneous hemorrhage into pancreatic necrosis is a rare but life-threatening complication. Because CT is almost always performed with contrast enhancement, this complication is rarely identified with imaging. The diagnosis is made by noting a drop in hemoglobin and hematocrit.

Hemorrhage into the retroperitoneum or the peritoneal cavity, or both, can occur when an inflammatory process erodes into a nearby artery. Luminal gastrointestinal bleeding can occur from gastric varices arising from splenic vein thrombosis and resulting left-sided portal hypertension, or from pseudoaneurysms. These can also bleed into the pancreatic duct (hemosuccus pancreaticus). Pseudoaneurysm is a later complication that occurs when an arterial wall (most commonly the splenic or gastroduodenal artery) is weakened by pancreatic enzymes.²³

Prompt recognition of hemorrhagic events and consultation with an interventional radiologist or surgeon are required to prevent death.

Inflammation and abdominal compartment syndrome

Inflammation from necrotizing pancreatitis can cause further complications by blocking nearby structures. Reported complications include jaundice from biliary compression, hydronephrosis from ureteral compression, bowel obstruction, and gastric outlet obstruction.

Abdominal compartment syndrome is an increasingly recognized complication of acute pancreatitis. Abdominal pressure can rise due to a number of factors, including fluid collections, ascites, ileus, and overly aggressive fluid resuscitation.²⁴ Elevated abdominal pressure is associated with complications such as decreased respiratory compliance, increased peak airway pressure, decreased cardiac preload, hypotension, mesenteric and intestinal ischemia, feeding intolerance, and lower-extremity ischemia and thrombosis.

Patients with necrotizing pancreatitis who have abdominal compartment syndrome have a mortality rate 5 times higher than patients without abdominal compartment syndrome.²⁵

Abdominal pressures should be monitored using a bladder pressure sensor in critically ill or ventilated patients with acute pancreatitis. If the abdominal pressure rises above 20 mm Hg, medical and surgical interventions should be offered in a stepwise fashion to decrease it. Interventions include decompression by nasogastric and rectal tube, sedation or paralysis to relax abdominal wall tension, minimization of intravenous fluids, percutaneous drainage of ascites, and (rarely) surgical midline or subcostal laparotomy.