clavien_atlas_of_upper_gastrointestinal_and_hepato-pancreato-biliary_surgery2007-10-01_3540200045_springer

904 SECTION 6 Pancreas

Planned Repeated Necrosectomy

Gregory G. Tsiotos, Michael G. Sarr

STEP 1

The operation begins with a systematic, comprehensive, manual and visual exploration of the entire pancreas as well as an exploration to delineate the extent of necrosis in both paracolic gutters, the root of the small bowel mesentery below the transverse mesocolon, and the suprapancreatic retroperitoneal tissues. CT is the guide to locating all areas of necrosis.

Entrance into the lesser omental sac is through the gastrocolic ligament (as opposed to through the transverse mesocolon), as this approach provides superior access to the pancreatic bed not hindered by risking injury to the middle colic or right colic vessels. Although necrosis often presents through the left mesocolon when the pancreatic body and tail are involved or through the right mesocolon when the head and uncinate are involved, any approach from below the mesocolon for a complete pancreatic necrosectomy offers suboptimal exposure and risks inadvertent surgical trauma and incomplete necrosectomy. We believe that exposure via the gastrocolic ligament is especially important for necrosis of the body and tail, except when the necrotizing process involves predominantly the head and uncinate process of the pancreas or when previous pancreatic surgery has obliterated the lesser sac.

Probing the gastrocolic ligament bluntly with a finger will usually identify the cavity containing the necrosis in the lesser sac. Once the finger finds the cavity, the space is unroofed in a controlled fashion, with care to protect the gastroepiploic arcade and vessels in the transverse mesocolon.

STEP 2

The actual necrosectomy should be carried out by manual, blunt dissection as the technique of choice. Gentle “scooping out” of the putty-like necrosis is sufficient in most cases. Sharp necrosectomy (using knife or scissors) is specifically condemned, especially in the vicinity of the splenic and superior mesenteric veins and in the area of the middle colic vessels. All devitalized tissue amenable to blunt debridement should be removed. The initial necrosectomy offers the best possible exposure, and thus every attempt at a complete and safe necrosectomy should be pursued at this time.

STEP 3

When the necrotic material must be accessed through the gastrocolic ligament, extreme care should be taken to avoid injury to the transverse colon and its mesentery, which is often shrunken, thickened, less immobile, and involved in the obliterated lesser sac region.

When necrotic tissue remains adherent to viable tissue, blunt avulsion or sharp dissection away from the viable tissue may cause bleeding that is difficult to control. These areas will auto-separate from the viable tissue at the time of planned reexploration 2 or more days later. Similarly, inflamed, friable, hypervascular, but viable tissues are not disturbed to minimize blood loss.

During removal of a piece of necrosis, a band or straw-shaped bridge of tissue may span the now defined cavity. Although the tendency is to avulse this persistent bridge of tissue, the surgeon should avoid the urge to do so, because this usually represents a blood vessel, often with persistent flow. Any uncontrolled, active bleeding during

necrosectomy may be difficult to control in this inflamed peripancreatic space. Similarly, ligation or suture closure of a major blood vessel will then be subject to pseudoaneurysm formation; the overall goal of the necrosectomy should be to evacuate all necrosis without inducing hemorrhage.

STEP 4

The peritoneum overlying both paracolic gutters should be incised to visualize and expose the retroperitoneal tissues, especially if the CT shows extension of the “inflammation” in these regions; simple palpation can be deceiving as to the presence or absence of peripancreatic fat necrosis, especially in the obese patient. These spaces, if involved, should be unroofed either medially to their colonic mesenteries, or, if more extensive, via a lateral approach with medial mobilization of the colon. The root of the small bowel mesentery and the suprapancreatic area (e.g., periesophageal and periaortic regions) are other locations where the necrotizing process can be concealed as it dissects along the superior mesenteric vessels.

After the necrosectomy, we irrigate the debrided areas extensively to remove devitalized tissue, inflammatory exudate, and residual bacteria using the Water-Pik irrigator (Surgiluv, Model 201, Stryker, Kalamazoo, MI), because it provides a controlled pressure system of blunt, liquid debridement and irrigation.

STEP 5

When areas of questionable viability are noted which remain adherent to viable areas, we return the patient to the operating room 2days later for a repeat operative exploration and necrosectomy under a general anesthesia. In these patients after the initial necrosectomy, the debrided areas are packed with moistened sponges; if exposed, the splenic or superior mesenteric vessels are protected by interposition of a layer of nonadhesive dressing such as Adaptic (Johnson & Johnson, Kalamazoo, MI) or a thin layer of silastic sheeting. Soft, closed-suction drains are positioned on top of the gauze packing to evacuate free fluid that might otherwise accumulate and increase intra-abdominal pressure.

Abdominal wall closure proceeds with a zipper sewn to the fascia. This not only speeds opening and closure during any planned operative re-debridements, but also maintains the abdominal domain between debridements, facilitating a delayed primary wound closure and pulmonary ventilation. We specifically avoid sewing the zipper to the skin, because this allows the fascia to retract laterally, making later fascia closure more difficult or impossible. Reoperation is planned for 48h after the current procedure and proceeds as described above. The zipper is opened and the abdomen fully reexplored in a systematic fashion. Additional necrosectomy and blunt debridement is performed as needed. The process is repeated at 48-h intervals until the necrotizing process has been arrested as evident by cessation of suppuration and absence of necrosis. If at the first necrosectomy a complete necrosectomy is performed as is usually possible when the necrosectomy occurs >21days after onset of pancreatitis, then the abdomen is closed without planned reexploration.

STEP 6

When convinced that all necrotic debris has been removed, the abdomen is closed over drains. We prefer soft, closed-suction silastic drains, which minimize risk of pressure necrosis of adjacent structures. We avoid large stiff “sump” drains with large holes, because with our technique of late (rather than early) first necrosectomy, followed by planned reoperations, only minimal particulate matter remains in the region and large bore drains are unnecessary.

The drains should be positioned away from major vessels and from direct contact with the colon or small bowel. We are very liberal in the number of drains placed, with at least one drain in each anatomic area of necrosis. Drains are routed below the liver and posterior to the hepatic flexure on the right and posterior to the splenic flexure inferior to the lower pole of the spleen on the left. A gastrostomy tube for gastric decompression and a needle catheter jejunostomy for eventual enteral feeding are inserted.

At final closure, the zipper is removed, and the abdominal wall is closed with nonabsorbable suture. The skin remains packed open.

Gently insert the nephroscope along the Amplatz sheath to enter the cavity. Again the initial step is to lavage/aspirate cavity to allow the pus-filled cavity to

run clear.

Once devitalized tissue is identified, loose material is removed carefully using forceps.

Use soft grasping forceps to avoid trauma.

Adherent material is left in situ for removal at a subsequent exploration; over zealous debridement may result in major hemorrhage.