Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

STEP 4: POSTOPERATIVE CARE

The patient will be monitored for adequate analgesia. This can be quite challenging in patients who have had large doses of narcotics preoperatively. Assuming we have used intraoperative epidural anesthesia, this problem is less significant because analgesia is better achieved with this modality.

In the first 24 hours, we monitor for hemorrhage and hyperglycemia. Glycosuria may be mistaken for euvolemia.

A nasogastric tube is used, and this is removed on the first postoperative day and a liquid diet is begun. If tolerated, this is advanced to a regular diet.

During the first 3 to 5 days postoperatively, we monitor for evidence of endocrine or exocrine insufficiency and treat these as necessary with either enzyme supplementation or insulin. It should be noted that the actual degree of functional derangement will not be fully appreciated until the patient has resumed a full diet and is tolerating food well.

The process of reducing and finally eliminating narcotic use will require weeks or months of effort after discharge.

STEP 5: PEARLS AND PITFALLS

We have added the use of the interrupted 2-0 Prolene around the circumference of the head of the pancreas in the Frey procedure. We use a large needle and make an effort to place sutures deeply to achieve adequate hemostasis. Ischemia to the duodenum is extremely unlikely.

The actual amount of tissue removed during the excavation will differ based on the size of the inflammatory mass preoperatively.

Note that the significant difference between the two procedures is that the body of the pancreas is not divided in the Frey procedure as it is in a Beger procedure. Avoiding this step will make less likely any significant encounter with the superior mesenteric vein/portal vein complex. In the inflammatory changes, which are seen in chronic pancreatitis, the plane between the pancreas and these delicate structures is treacherous and therefore best avoided. Comparisons of outcome in these procedures have been identical in large series.

Because an amount of pancreatic parenchyma has been removed, one can anticipate a percentage of patients who will sustain functional derangements as a result of this procedure.

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SELECTED REFERENCES

1. Di Sebastiano P, Di Mola F, Friess H: Management of chronic pancreatitis: Conservative, endoscopic and surgical. In Blumgart LH (ed): Surgery of the Liver, Biliary Tract and Pancreas, 4th ed. Philadelphia, Saunders, 2007, pp 728-740.

2. Buchler M, Friess H, Bittner R, et al: Duodenum preserving pancreatic head resection: Long term results. J Gastrointest Surg 1997;1:13-19.

3. Frey CF, Amikura K: Local resection of the head of the pancreas combined with longitudinal pancreaticojejunostomy in the management of patients with chronic pancreatitis. Ann Surg 1994;220:492-507.

C H A P T E R 49

PYLORUS-SAVING

PANCREATICODUODENECTOMY

William H. Nealon

STEP 1: SURGICAL ANATOMY

All pancreatic surgery requires an understanding of the anatomic relationships in the lesser sac. After either an upper midline or a bilateral subcostal (chevron) incision, one enters the lesser sac by dissecting along the avascular plane at the points of attachment of the gastrocolic omentum to the transverse colon (Figure 49-1). The proper plane is between the anterior and posterior leaflets. This is my favored point of entry. The alternative entry is by transversely dividing and ligating the vascular structures embedded in the omentum while preserving the gastroepiploic vessels located along the greater curvature of the stomach.

Upon entering the lesser sac, one will encounter varying amounts of adhesions between the posterior wall of the stomach and the anterior surface of the pancreas. These fetal adhesions do not imply prior inflammatory events. Considerable dense adhesions may be encountered in pathologic states.

FIGURE 49–1

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The pancreas is essentially encased in a sandwich of major blood vessels. The vena cava and aorta occupy the posterior surface in the midline. The splenic artery courses along the superior surface from the aorta toward the tail. The splenic vein occupies the posterior superior surface of the body and tail of the pancreas. It meets the superior mesenteric vein, which is oriented vertically in the groove created by the uncinate process in the posterior aspect of the head of the pancreas and the right lateral and anterior components of the head. The confluence of these two veins constitutes the portal vein, which traverses this uncinate groove and emerges to join the bile duct and the hepatic artery in the hepatoduodenal ligament (see Figures 49-1, 49-3, and 49-4).

The superior mesenteric artery is located in a plane posterior and slightly medial to the superior mesenteric artery. The common hepatic artery, another branch of the celiac trunk (along with the splenic artery and left gastric artery), courses along the superior border of the head of the pancreas to join the hepatoduodenal ligament. Its first branch is the typically miniscule right gastric artery. Just distal is the more substantial gastroduodenal artery, which emerges at a right angle to the hepatic artery from its inferior surface and courses beneath the pylorus. After sending the right gastroepiploic artery in the plane between the inferior aspect of the pylorus and the superior surface of the head of the pancreas, the gastroduodenal artery pierces the head of the pancreas (see Figures 49-4 and 49-5).

The anterior superior and the posterior superior pancreaticoduodenal arteries also arise from branches of the gastroduodenal artery. These arteries form an arch medial to the C-loop of the duodenum, and they collateralize with branches of the anterior and posterior inferior pancreaticoduodenal arteries, which are branches of the superior mesenteric artery. Small branches from these arteries provide blood supply to the duodenum (see Figures 49-3 through 49-6).

Key anatomic features in pancreatic head resections are the network of tributaries projecting between the superior mesenteric vein/portal vein confluence and the uncinate process. These tributaries are located at the right lateral aspect of the veins. These tiny veins exit the pancreas at the mid-portion of the groove in which the major veins reside (see Figure 49-12).

Viewed in cross-sectional imaging, the uncinate process forms a C-shaped structure. The terminal posterior extent of the uncinate process projects in a medial direction as a ligamentous structure and contains a variable number of arterial branches from the superior mesenteric artery, which project at right angles to the major artery and provide blood supply to the uncinate process. Division of the tiny venous tributaries and the arterial branches are key steps in respective procedures. This uncinate margin is the most problematic in managing malignant tumors in the head of the pancreas (see Figure 49-13).

The pancreas is entirely retroperitoneal, and therefore operative procedures will require mobilization of the pancreas from its retroperitoneal position. The plane lateral to the C-loop of the duodenum is incised in nearly all procedures; this plane is avascular, and its mobilization is termed the Kocher maneuver. This exposes the vena cava and aorta, and it permits “bimanual palpation” of the head of the pancreas. The dissection may be easily extended to the fourth portion of the duodenum and the ligament of Treitz (see Figure 49-3).

The inferior border of the body of the pancreas is also avascular, although the inferior mesenteric vein may be encountered to the right of the spine (see Figure 49-4).

Peritoneum overlies the hepatoduodenal ligament. Dissection reveals the triad in gross anatomic terms, which corresponds to the microscopic portal triad—with portal, hepatic arterial, and biliary structures. The common bile duct is located in an anterior lateral position, and the hepatic artery is anterior medial. The portal vein is positioned in the posterior groove created by the apposition of these anterior structures (see Figure 49-5).

Although lymph nodes may be seen at a wide array of locations, there is a constant lymph node in the groove created by the lateral border of the second portion of the duodenum and the hepatoduodenal ligament. Dissection of this lymph node is necessary to fully visualize the proximal hepatic artery. Other common sites of lymph nodes are on the lateral aspect of the mid-portion of the hepatoduodenal ligament, in the fibrovascular bundle surrounding the right gastroepiploic complex, and on the superior border of the confluence of the head and body of the pancreas. Beneath this lymph node one finds the origins of the common hepatic artery and the splenic artery.

On the inferior border of the pancreatic head, just where the duodenum dives beneath the superior mesenteric vein and artery, one may dissect the peritoneum and visualize the superior mesenteric vein as it passes in a superior direction beneath the head of the pancreas.

The ligament of Treitz is a significant anatomic structure, and it can be accessed by lifting the transverse colon and omentum in an anterior direction. The ligament can be seen to the left of the spine.

The main pancreatic duct originates in the tail of the pancreas and traverses the length of the pancreas to exit in the duodenum through both main ampulla (Vater) and the accessory ampulla, which is located more proximally in the duodenum. The main pancreatic duct (Wirsung) and the minor or accessory duct (Santorini) fuse during fetal development at what is termed the genu or “knee” of the duct.

STEP 2: PREOPERATIVE CONSIDERATIONS

Establishment of the indications for pancreatic resection depends on imaging; pathologic confirmation; establishment that curative intent can be applied; and assessment of the medical status of the patient, including nutritional state.

In the case of cancer, it is not unusual to proceed to resection without pathologic confirmation. In this case, a very experienced pancreatic surgeon must make that determination based on strong evidence by imaging that malignant disease exists.

Resectability of pancreatic cancer in the head must be founded on the presence of metastatic disease (typically in the liver, but potentially many remote sites, as well) and the presence of what has been termed “locally advanced” disease. In the case of adenocarcinoma of the head of the pancreas, local invasion and/or encasement of the superior mesenteric artery or vein are the primary elements that establish this clinical stage. In several large series, local extension is responsible for establishment of unresectability in half of those deemed not to be operative candidates.

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Both chronic pancreatitis and cystic neoplasms such as intraductal papillary mucinous neoplasm (IPMN) are nonmalignant diagnoses that are treated appropriately with radical resection. Because pancreatic cancer may masquerade as chronic pancreatitis or coexist with it, a confirmation of that distinction is not possible. Suspicions to favor chronic pancreatitis are the presence of glandular calcification, the presence of a pancreatic mass in the absence of clinical jaundice, and the chronicity of symptoms. We favor making a strong effort to confirm the diagnosis of IPMN before proceeding to resection.

Because of the magnitude of the operative procedure, care must be taken to exclude significant cardiac, pulmonary, and renal disease and to determine the presence of diabetes mellitus. Nutritional needs must also be addressed before surgery.

STEP 3: OPERATIVE STEPS

1.INCISION

Midline/xiphoid to some distance below the umbilicus (Figure 49-2)

Self-retaining retractor such as Thompson retractors