Anatomy - Necrosectomy and continuous closed irrigation in infected hemorrhagic-necrotizing pancreatitis

Incidence/Etiology

For the first occurrence of acute pancreatitis, the incidence in Western Europe is approximately 30 cases per 100,000 inhabitants per year.

75–80% of all cases in Western cultures are caused by biliary or alcohol toxicity, 10% are idiopathic.

10% show rare causes such as hypercalcemia, hypertriglyceridemia, tumor (cystic), pancreas divisum, dysfunction of the sphincter of Oddi, or are drug-induced or hereditary.

Clinical Presentation

Acute pancreatitis is characterized by abdominal pain accompanied by an increase in amylase and/or lipase to at least three times the normal level.

The course of acute pancreatitis varies from mild self-limiting (80%) to severe necrotizing form (20%).

The clinically severe form is associated with pancreatic tissue necrosis, a high rate of organ complications, and high mortality. Long-term pancreatic damage is expected in survivors.

The most severe clinical form shows early systemic organ complications with SIRS, sepsis, multi-organ failure, and very high mortality.

Since even in severe acute pancreatitis, very different clinical courses can be observed, the new Atlanta classification groups patients with regression of severe symptoms within the first week into an intermediate group.

Atlanta Classification

• Atlanta (1993)

 2 groups: mild – severe

• Modified Atlanta (2012)

 3 groups:

mild acute pancreatitis:

(¡) no organ failure

(¡¡) no local or systemic complications

moderately severe acute pancreatitis:

(¡) organ failure that resolves within 48 hours (transient organ failure) and/or

(¡¡) local or systemic complications without persistent organ failure

severe acute pancreatitis: persistent organ failure (> 48h)

(¡) single organ failure

(¡¡) multiple organ failure

Prognosis

Advances in the understanding of pathophysiology and modern, interdisciplinary intensive care management of life-threatening organ complications have significantly increased the success rate of therapy.

A proven infection of pancreatic necrosis is an absolute indication for surgery/intervention.

Through modern stage-appropriate therapy using available interventional and surgical methods in specialized centers, the mortality of necrotizing pancreatitis can be reduced to about 15–20%.

The reduction in mortality is primarily due to improved intensive care monitoring and therapy in the early phase, as well as the latest possible surgical intervention, since particularly surgery in the early phase of the disease (within the first 14 days) is associated with very high morbidity and mortality and should therefore be avoided whenever possible according to international consensus.

The quality of life for most patients is good after discharge from the hospital, and almost 90% of patients can return to work. Only with persistent alcohol consumption is there a mortality rate of about 10% in the following years, even after initially good recovery.

The pancreas, composed of lobules, has a reddish-gray color, is 14 – 18 cm long, and weighs 65 – 80 grams. It is located at the level of the 1st and 2nd lumbar vertebrae and extends wedge-shaped from the epigastric region to the left hypochondriac region. Due to its developmental history, the organ is in close proximity to the upper abdominal organs and vessels.

The pancreas is encased in capsule-like connective or fatty tissue and is divided into three sections: head, body, and tail. While a somewhat firmer connective tissue plate is located in the posterior head area, the gland is otherwise loosely connected dorsally with the connective tissue. As a retroperitoneal organ, the gland is covered with peritoneum on its anterior surface.

The widest part of the gland is the head of the pancreas, which – located to the right of the spine – fits into the loop formed by the duodenum. Both the anterior and posterior surfaces of the duodenum can be overlaid by glandular tissue to varying extents here. The head encompasses with its caudal portion (uncinate process) from behind the superior mesenteric vein, occasionally also the artery. The groove located in the uncinate process and the remaining part of the pancreatic head is referred to as the pancreatic notch.

The part of the pancreas located at the level of the 1st lumbar vertebral body, with a width of about 2 cm, represents the transition area from the head to the body and lies over the superior mesenteric vessels. From a surgical perspective, this section is also referred to as the neck of the pancreas.

The elongated body of the pancreas runs obliquely upwards over the 1st and 2nd lumbar vertebrae, bulges ventrally into the omental bursa, and arches towards the splenic hilum, with the transition into the tail occurring without precise anatomical demarcation. Dorsal to the body are the aorta, the inferior vena cava, and the superior mesenteric artery and vein, alongside the spine.

The tail of the pancreas forms the pointed continuation of the glandular body and extends to or into the splenorenal ligament.

The pancreas can be configured in various shape variants, including oblique, S-shaped, transverse, and L-shaped. A horseshoe shape and an inverted V-shape have also been described. The transitions between the shape variants are fluid.

Topographically, the pancreas has the following relationships to adjacent organs and retroperitoneally located conduits:

• ventrally, the omental bursa and the posterior surface of the stomach
• to the right, there is a close relationship between the head and the duodenal loop
• to the left, there is a close relationship to the splenic hilum
• the posterior wall of the pancreas touches at the level of the head the portal vein, the superior mesenteric artery and vein, and the common bile duct, at the level of the body the splenic artery and vein, the inferior mesenteric vein, the inferior vena cava, and the abdominal aorta, at the level of the tail the left kidney

The approximately 2 mm thick ductus pancreaticus traverses the organ in its longitudinal extension near the posterior surface and receives numerous short glandular ducts that enter it perpendicularly along its path. In about 77% of cases, the ductus joins with the ductus choledochus at the papilla duodeni major in the posterior wall area of the descending part of the duodenum; in the remaining cases, the openings of both ducts are located close to each other. The ductus pancreaticus accessorius, an accessory duct, is often only rudimentarily developed or completely absent. If present, it opens at the papilla duodeni minor.

The arterial supply of the pancreas is provided by the superior pancreaticoduodenal artery, which originates from the common hepatic artery, and the head of the pancreas is additionally supplied by the inferior pancreaticoduodenal artery, which comes from the superior mesenteric artery. While the blood supply of the head is relatively constant, the body and tail have a variable vascular supply: short arteries originating from the splenic artery and branches of the transverse pancreatic artery.

The venous drainage from the head of the pancreas occurs via the superior mesenteric vein, while the body and tail belong to the drainage area of the splenic vein.

The lymphatic vessels of the pancreas run parallel to the blood vessels to all lymph nodes located in the immediate vicinity of the pancreas. The peripancreatic lymph nodes (1st station) are closely attached to the gland, sometimes even superficially present in the glandular parenchyma. At the upper edge of the organ, there is a chain of lymph nodes extending from the splenic hilum to the hepatoduodenal ligament, with additional lymph nodes located ventrally and dorsally between the pancreatic head and duodenum, at the lower edge of the pancreas, and in the caudal region. Other relevant lymph nodes are located near the celiac trunk, the superior mesenteric artery and vein, and on both sides of the aorta (2nd station or collecting lymph nodes).