Pancreatectomy

Anatomy and Physiology

Anatomy of the Pancreas

The pancreas is an oblong glandular abdominal organ that has both endocrine and exocrine functions. The organ lies in the retroperitoneum while crossing the body of L1 and L2 along the posterior aspect of the abdominal wall. The pancreas lies in a transverse plane between the C loop of the duodenum while the tail of the pancreas touches the hilum of the spleen. The pancreas is divided into five regions, which consist of a head, uncinate process, neck, body, and tail. The head of the pancreas is the widest part of the organ, while the uncinate lies underneath the body of the pancreas, coming off the posteromedial area of the pancreatic head and curving just posterior to the superior mesenteric artery and vein. The head of the pancreas lies just to the right of the superior mesenteric vessels, and it is attached to the second and third portions of the duodenum. The uncinate process lies adjacent to the third and fourth portions of the duodenum. The uncinate is absent in some people, can vary in size and thickness, and has also been noted to encircle the superior mesenteric vessels in others. 

The neck begins at the passage of the superior mesenteric vessels and spleno-portal vein confluence posterior to the gland. The neck is the thinnest portion of the pancreas and can be crushed in blunt trauma by being compressed against the second lumbar vertebrae, which sit just posterior to the neck. The gastroduodenal artery runs in a superior to inferior fashion just to the right of the neck of the pancreas. The body of the pancreas is covered anteriorly by the omental bursa, which separates the stomach from the pancreas. The body lies just to the left of the aorta. The tail of the pancreas is the most mobile aspect of the gland. The tail usually rests in the hilum of the spleen or just below in the majority of people.[1]

Anatomy of the Pancreatic Ductal System and Embryology

Beginning as an outpouching from the primitive endoderm foregut, the pancreas is formed by the fusion of ventral and dorsal pancreatic buds. The inferior portion of the pancreatic head and the uncinate process develop from the ventral bud while the body and tail arise from the dorsal bud. This bud fusion allows the two ductal systems also to fuse together. The main pancreatic duct of Wirsung arises from the ventral bud, while the dorsal duct gives rise to the accessory duct of Santorini. The fusion of the two ducts occurs in the head of the gland.

The majority of pancreatic enzymes are drained through the main pancreatic duct, which then drains out the common channel, which is formed after the meeting of the common bile duct and main pancreatic duct. The common channel length is variable in many patients. The superior and anterior portions of the pancreatic head are drained by the accessory duct of Santorini, with the remaining portions of the pancreas being drained by the main pancreatic duct of Wirsung. After the main pancreatic duct and common bile duct join, they enter into the 2nd portion of the duodenum and drain through the ampulla of Vater. The ampulla is surrounded by a muscular ring called the sphincter of Oddi, which controls the flow of bile and pancreatic fluid into the duodenum. This sphincter is under strict neural and hormonal control. It is very sensitive to cholecystokinin, which is produced in the duodenum and causes relaxation of the sphincter. There is often a second duct that drains into the duodenum, called to the minor papilla. The minor papilla is actually located superior to the Ampulla of Vater in the wall of the duodenum. There are multiple congenital variations in the bile and pancreatic ductal systems; these are discussed elsewhere. 

Arterial, Venous, and Lymphatic supply of the Pancreas

Arterial Supply of the Pancreas

• The vascular supply of the pancreas is very complex and is derived from both the celiac artery and the superior mesenteric artery. The common hepatic artery and splenic artery both arise from the celiac trunk. The common hepatic artery gives rise to the gastroduodenal artery (GDA); the GDA then gives rise to the right gastroepiploic artery after which it continues inferiorly becoming the anterior and posterior superior pancreaticoduodenal arteries. The superior mesenteric artery supplies both the inferior anterior and posterior pancreaticoduodenal arteries. These two superior and inferior pancreaticoduodenal arteries supply the pancreatic head, 2nd, and 3rd portions of the duodenum. The rich blood supply to this area is what allows duodenal sparing pancreatic surgery to be performed. The remaining portions of the pancreas are supplied by the splenic artery and superior mesenteric artery. The splenic artery runs along the superior aspect of the pancreas and gives off many branches. Three named arteries arise from the splenic artery, which runs perpendicular across the pancreatic body and tail. These arteries are named from medial to lateral- the dorsal, great, and caudal pancreatic arteries. These three arteries help form collateralization between the splenic artery and the inferior pancreaticoduodenal arteries. Overall, the pancreas has a rich blood supply, which must be taken into account when planning any surgical procedure involving this gland. High-quality CT imaging is a must, not only to view the pathological disease process (i.e., cancer or lesion) but to have an excellent visualization of the vessels during surgical planning. This could make the cancerous lesion unresectable. While there can be some disagreement regarding the exact definition of a borderline resectable lesion, in general, these all involve vascular determination, including- abutment of the superior mesenteric artery, celiac artery, or hepatic artery, all less than 180 degrees or have very small areas that are occluded along the portal vein, the superior mesenteric vein that may possibly have the need for reconstruction. Tumors that circumferentially encase the celiac artery, hepatic artery, or the superior mesenteric artery greater than 180 degrees or have complete occlusion of the superior mesenteric vein or portal vein with no possibility of reconstruction are considered locally advanced and surgically unresectable.[2] CT imaging also provides the surgeon with the chance to review any anatomical variants that may be present. A replaced right hepatic artery is the most common arterial variant, with the artery arises from the superior mesenteric artery. This variant is found in roughly 15% of the population. The replaced artery runs posterior and superior to the superior mesenteric artery and then posterior to the portal vein along the right side of the porta hepatis. Accidental injury to this artery can result in liver ischemia or cause a newly formed anastomosis to fail. Another anatomical variant is a replaced left hepatic artery, which occurs in less than 10% of the population. The replaced artery arises from the left gastric artery, travels along the superior aspect of the lesser omentum, and can be involved in pancreatic body tumors on rare occasions. 

Venous, Lymphatics, and Innervation of the Pancreas

• Venous drainage of the pancreas usually mirrors the arterial supply of the gland. The veins are usually located anteriorly to the arteries, while the pancreatic ducts are anterior to both arteries and veins. The venous drainage goes into the superior mesenteric vein, inferior mesenteric vein, splenic vein, or portal vein. Like the arterial system to the body and tail, three major veins drain these areas. The inferior pancreatic, caudal, and great pancreatic veins all drain directly into the splenic vein. These veins are of great importance when a spleen preserving distal pancreatectomy is performed as all these branches must be divided and ligated. 
• Lymphatic drainage of the pancreas aligns with the vessels supplying the gland. Metastatic disease from the pancreas is present in up to 70% of patients in their lymph nodes. The pancreas' lymphatic system consists of five main groups referred to as the anterior, posterior, superior, inferior, and splenic lymph nodes. The superior half of the pancreatic head drains into the superior lymph nodes while the inferior portion of the pancreatic head drains into the inferior lymph nodes. The pancreatic head also drains to a portion of nodes located at the right side of the celiac and superior mesenteric arteries. The pancreatic body is divided into a superior and inferior portion for lymph drainage; the superior aspect drains into the superior nodes while the inferior portion drains into inferior pancreatic, superior mesenteric, and also para-aortic lymph nodes. The tail of the pancreas drains directly into the splenic lymph nodes.
• Both sympathetic and parasympathetic nerves innervate the pancreas. The nerves follow the pathway of the vessels that supply the pancreas. The vagus nerve is the parasympathetic innervation which comes from the celiac plexus. The vagus nerve is mainly a sensory nerve in its function. The sympathetic innervation begins in the thoracic spinal cord then runs through the greater and lesser splanchnic nerves. Pancreatic pain is mainly transmitted through the celiac plexus; this is why a celiac nerve block can be used as a treatment for chronic pain in the setting of locally advanced cancer. 

Physiology

The pancreas performs both endocrine and exocrine functions. The endocrine portion only contributes 1% to 2% of the gland's function, while the majority of the pancreas is used for exocrine function.[3] The endocrine portion is responsible for glucose homeostasis, while the exocrine function is involved with the secretion of enzymes involved in digestion. The exocrine pancreas has a functional unit called an acinus. The acinus ultimately has cells that drain zymogen granules that subsequently drain into the main pancreatic duct. The acinar cells secrete either amylases, lipases, or proteases. Stimulation for the secretion of these enzymes is due to the parasympathetic system, secretin, and CCK. Usually, around 50% of the pancreatic acinar cells have to be damaged before there is an effect on their digestion function.[4] The acinar cell can secrete each of these enzymes, which ultimately appears as an alkaline fluid that is colorless and has no odor. The pancreas drains between 1 to 2 liters of exocrine fluid per day, which has an alkalotic pH due to the high bicarbonate concentration in the fluid. As pancreatic stimulation increases, so do the rate of bicarbonate, but chloride concentration decreases. 

The islets of Langerhans perform the pancreatic endocrine function. There are nearly one million islets in the normal functioning adult pancreas. These islets consist of 5 cell types- alpha cells that secrete glucagon, beta cells that secrete insulin, delta cells that secrete somatostatin, epsilon cells that secrete ghrelin, and F or PP cells that secrete pancreatic polypeptide.[5] The hormones are released in a balanced mixture into the portal vein in reaction to changes in the plasma levels.[6] 

The majority of the endocrine cells are located in the islet cell periphery, while the beta cells are located in the center and comprise 70% of the islet mass. Alpha cells are predominantly seen in the islet cells in the superior aspect of the pancreatic head, body, and tail; it accounts for 10% of the islet mass. Delta cells are like beta cells, which are present in all islets throughout the pancreas. Delta cells make up only 5% of the islet cell mass. PP cells are mostly seen in the islets in the pancreas' head and account for 15% of the islet mass. Endocrine and exocrine functions are extremely complex, so surgical planning for the patient must take into account the physiological function of the pancreas that will remain. Some patients may require exogenous administration of pancreatic digestive enzymes after surgery or insulin administration with frequent glucose monitoring. Roughly 20 % of the pancreas volume is needed in the remnant to avoid endocrine or exocrine insufficiency. This may not be the case for a more diseased or older fat replaced pancreas.

Indications

Indications regarding laparoscopic vs open pancreatectomy are relatively the same but rely heavily on the surgeon's experience and their comfort level with the technique. 

Total Pancreatectomy 

• Malignant tumors of the pancreatic head with involvement in the left pancreas
• Unable to obtain tumor-free R0 resections at the pancreatic margin
• Unable to perform pancreatic anastomosis after pancreaticoduodenectomy 
• Recurrent pancreatic cancer in the remnant pancreas
• Removal of the remaining pancreas after Whipple complication (bleeding or leak)
• multifocal intraductal papillary mucinous neoplasm (IPMN) in all parts of the pancreas
• multifocal neuroendocrine tumors of the pancreas with a history of  multiple endocrine neoplasias  
• Hereditary pancreatic cancer or Family history (controversial)
• Intractable pain due to chronic pancreatitis or multiple bouts of recurrent acute pancreatitis[7]

Distal Pancreatectomy

• Benign or malignant tumors involving the body or tail of the pancreas located to the left side of the superior mesenteric vein
• Chronic pancreatitis confined to the body or tail
• Pseudocyst involving the tail of the pancreas
• Trauma to the distal pancreas 
• Ductal disruption or stricture +/- pancreatic fistula in body or tail

Central Pancreatectomy 

• Benign or borderline lesions located in the neck or proximal body of the pancreas
• Enucleation of the lesion unable to be performed at the neck/proximal body
• Trauma-related injury to the neck/proximal body
• Among other considerations will need a distal pancreatic tail >5 to 6 cm to make pancreatic conservation worth the risk[8]

Contraindications

Absolute Contraindications to Open and Laparoscopic

• Medical comorbidities that prohibit operative intervention
• Poor functional status
• Bleeding coagulopathy

Laparoscopic Technique

• Severe obesity (surgeon experience level dependent)
• Previous major abdominal surgeries (adhesive disease)
• Advanced malignancy 
• Involving vascular structures (surgeon experience level dependent)
• Unable to tolerate pneumoperitoneum

Total Pancreatectomy

• Lesions that are amenable for removal with sparing of pancreatic tissue by another resection type

Central Pancreatectomy

• Pancreatic cancer (inability to remove all cancer and lymphatic involvement)

Distal Pancreatectomy

• Pancreatic lesions that are not able to be fully removed with a distal pancreatectomy or achieve an R0 resection. 

Equipment

• Sterile drapes, gowns, and gloves
• Operating room with surgical instruments, sutures, and staplers
• Cell saver machine
• If laparoscopic case (video monitors, straight or angled camera lenses, multiple laparoscopic instruments- scissors, graspers, and dissectors, laparoscopic staplers, energy devices, and sutures) 
• Ultrasound 
• Code cart
• Anesthesia
• Arterial and Venous lines
• Foley catheter
• Closed suction drains 
• Surgical loupes

Personnel

• Anesthesia team
• OR personnel (nurses and scrub techs)
• Surgeon
• First assistant 
• Skilled Ultrasonographer ( if there is not an OR room ultrasound immediately available for the surgeon's use)
• Cell saver technician

Preparation

An elective pancreatic surgical candidate must undergo a strict preoperative evaluation. A thorough history and physical examination must be performed on all patients. Current medical conditions and past surgical procedures must be taken into account when planning for surgery. The patient's current presenting signs and symptoms and past family history of cancer must all be included in the assessment. All pancreatic surgery should be performed in carefully selected patients. Preoperative labs, imaging, and overall status should be reviewed. Patients undergoing cancer resections should have preoperative Ca19-9 check for three reasons: 

1. If elevated confirming concern for malignancy
2. If exceedingly high raise suspicion for disseminated disease
3. A starting point to be utilized as a reference for post-operative monitoring

The vast majority of patients will undergo preoperative endoscopic ultrasound with biopsy.  Once the diagnosis of the pancreatic disease has been established, the proper steps must be taken to determine if the patient is a surgical candidate. The surgical planning team should undertake preoperative medical and cardiac clearance. In the preoperative planning phase, the patient’s cardiac and respiratory function should be medically optimized to help avoid any postoperative morbidity or mortality. These two body systems carry some of the biggest risk factors for postoperative complications after major abdominal surgery. The patient's nutritional status should be evaluated, as this has also been a marker of postoperative outcomes. Chronic pancreatitis and pancreatic cancer patients often have differing degrees of malnourishment. Multiple formulas and lab measures are used, but the clinician's clinical judgment of the patient should be the most important factor. Any signs of preoperative malnutrition should be addressed and managed accordingly.

Imaging

• CT imaging is an extremely valuable tool for the evaluation of pancreatic lesions. The CT can provide the precise location of the lesion, size, and, most importantly, any involvement of any surrounding structures. CT imaging can really help determine the resectability of the tumor. A pancreatic CT protocol involves triphasic cross-sectional imaging with arterial, late arterial, and venous phases. This type of imaging allows identification of the majority of pancreatic cancers in the delayed arterial phase/venous phase, as many are hypovascular in nature. However, the arterial phase can identify many other pancreatic lesions, as well.[9] CT imaging has a reported sensitivity ranging from 76-92% for diagnosing pancreatic cancer and surgical resectability up to 90%.[10] 

• Endoscopic ultrasound can be used in the preoperative and operative settings. The ultrasound can be used to look for vascular invasion and resectability of the mass. Endoscopic is best used to obtain a tissue biopsy. Endoscopic ultrasound is very useful in small pancreatic lesions such as cysts. Another useful advantage for ultrasound is the use of helping diagnose nodal involvement and metastatic diseases, such as with large lymph nodes in the celiac or mediastinal positions. 

• MRI also has a role in diagnosing pancreatic lesions. MRI is an excellent modality for determining pancreaticobiliary anatomy and pathology. MRCP can identify pancreatic duct abnormalities, such as strictures. It is better overall at identifying the biliary and pancreatic ductal systems. MRI is becoming more popular for diagnosing and following lesions post-operatively as well. 

• PET scans have conflicting evidence for the regular use in diagnosing and staging of pancreatic disease. The sensitivity depends on the lesion's size, so it is susceptible to miss small areas of disease. Elevated serum glucose levels can cause false negatives and cause missed metastatic disease. When CT and PET scans are combined, this can increase the overall accuracy while increasing the sensitivity and specificity, especially for lesions that were missed on CT imaging.[11] Overall, more useful in finding and confirming occult disease post-resection with CA 19-9 increases.[12]

Technique or Treatment

Laparoscopic vs. Open Techniques

• Over the course of the last decade, significant advances have been made with minimally invasive techniques for the management of benign or malignant processes. In the past laparoscopic techniques were only used for diagnostic staging of pancreatic cancer. Many surgeons are now using either robotic or laparoscopic techniques to perform central, distal, or enucleation resections on the pancreas. Laparoscopic techniques offer the patient less postoperative pain, shorter hospital stay, less intraoperative blood loss, quicker return to daily activities, less postoperative ileus, and overall fewer surgical complications. Laparoscopic techniques are very complicated and should only be undertaken by surgeons with advanced training in minimally invasive surgical techniques. The surgeon must be comfortable with laparoscopic ultrasound techniques, laparoscopic staplers, controlling bleeding laparoscopically, and suturing with an intracorporeal technique. 

• If the patient is scheduled for a pancreatic procedure due to a malignant lesion, the patient usually undergoes a diagnostic laparoscopy first. This is performed by the use of a Veress needle for the creation of pneumoperitoneum or by a Hasson technique for cutdown to the fascia with the placement of the trocar under direct visualization of the fascia. After the placement of an infraumbilical or supraumbilical trocar, the camera can be placed into the abdomen with direct visualization of the anatomy. Separate trocars can then be placed under direct vision with the camera. After the other 5mm working ports are placed, graspers can be used to explore the abdomen making sure there is no unseen metastatic disease noted to the peritoneum, liver, or surrounding structures. More biopsies or peritoneal washings can be taken at this time. Once no metastatic disease has been established, the laparoscopic technique can continue, or the team can convert to open for the resection or proceed in a minimally invasive fashion if this is their usual surgical technique. 

Open Techniques

• The following will describe the usual set up for an open pancreatic surgical operation. The remaining techniques will describe the exact operative maneuvers for completing the case. 

• All preoperative imaging was reviewed. Informed consent was obtained. The patient will be transferred to the operating room and placed on the operating room table in the supine position. The majority of the patients undergo a spinal block for postoperative pain control via the anesthesia team. The patient will undergo general anesthesia with endotracheal intubation. Depending on patient factors, as well as surgeon and anesthesiologist's judgment and comfort level, an aline and/or central line may be placed.  A formal timeout is called verifying the correct patient, positioning, procedure to be performed, and preoperative antibiotics. The patient will receive a pre-incision antibiotic. A Foley catheter will be placed. The patient's abdomen will then be prepped and draped in the usual sterile fashion from the nipples to the suprapubic region. Diagnostic laparoscopic, as previously described, is undertaken first.  If negative, then proceed with a midline incision extending from the subxiphoid region to the supraumbilical region is performed using a # 10 blade scalpel. A subcostal/Chevron incision can also be performed. Once into the abdomen, the falciform ligament should be ligated and taken down for later use if needed. After entering into the abdomen, a multitude of surgical retractors can be used, such as a Bookwalter, Omni -Tract, or Thompson retractor sets. Exploring the abdomen should again be performed to definitely rule out any metastatic disease findings by inspecting the liver, small bowel, transverse colon, mesentery, diaphragm, and peritoneum. The gastrocolic ligament should be entered near the transverse colon to open the lesser sac for visualization of the pancreas. The pancreas is then exposed to the surgical resection that is going to be performed. The exact maneuvers and techniques for the listed pancreatic surgery are listed below. 

Total Pancreatectomy

• A total pancreatectomy requires exposure of the entire organ. The hepatic flexure is mobilized as needed to allow for a full kocherization of the duodenum extending to the aorta. This complete Kocher maneuver allows full visualization of the head of the pancreas with a direct view of the retroperitoneal attachments. The surgeon can then place their hand behind the head of the pancreas to palpate for any masses involving the superior mesenteric artery meaning that an R0 resection could not be obtained). The gastrohepatic ligament can then be dissected with full circumferential exposure of the common bile duct. The gallbladder can then be dissected from the fossa with separation from the liver bed. The cystic artery and cystic duct can then be fully dissected with clip ligation and division.
• After removal of the gallbladder from the liver bed, confirmation of a replaced or accessory right hepatic artery can be confirmed. The celiac axis can be identified with dissection of this lymph node station. The gastroduodenal artery can then be identified and clamped. The transverse mesocolon can then be examined for the middle colic vein. This can be traced to the inferior aspect of the pancreas to the location of the superior mesenteric vein. The superior mesenteric vein and portal vein confluence can then be safely dissected using a blunt right-angled instrument. After careful dissection, a Penrose drain can be placed between the dissection plane of the portal vein and superior mesenteric vein. Next, the proximal jejunum can be located 10 to 15 cm distal to the ligament of Treitz. This area can be divided using a linear GIA stapler. The mesentery can then be taken down at the bowel edge using a ligature device.
• The newly created jejunal limb can be placed into the supracolic compartment at the defect of the ligament of Treitz. The defect can be closed to prevent any internal hernia formation. The porta hepatis can then be identified with transection of the hepatic duct, just proximal to the ligated cystic duct. The portal vein and hepatic artery can be identified posteriorly. Care must be taken not to injure these structures. The gastroduodenal artery can be further dissected then ligated with the removal of the clamp. At this point, a pylorus-preserving pancreaticoduodenectomy can be performed or the standard pancreaticoduodenectomy. For the pylorus-preserving technique, the second portion of the duodenum can be dissected with the division of the duodenum 3 cm distal to the pylorus. If the standard technique is to be used, the terminal branches of the right and left gastric arteries can be ligated and then divided at the antrum and body of the stomach.
• The vagus nerve should be identified, division of the antrum of the stomach can be performed just distal to the vagus nerve (typically located at the third crossing vein proximal to the pylorus). The spleen and left colon at the splenic flexure can then be further mobilized. The short gastric arteries can then be taken down using a ligature energy device. The spleen and its surrounding attachments can then be fully mobilized along with the retroperitoneal attachments of the spleen and pancreas. The dissection is then carried from the medial aspect of the pancreas toward the spleen. The beginning of the splenic artery and the confluence of the superior mesenteric vein- splenic vein junction should be identified. The splenic artery and vein can then be ligated at the origin of the arterial take off from the celiac trunk. The small draining veins from the pancreas and duodenum can then be identified and ligated as they enter the portal vein and superior mesenteric vein. The uncinate process can then be removed from the posterior attachments of the portal vein, superior mesenteric artery, and superior mesenteric vein. The venous vessels of the pancreatic head are then taken down with careful dissection and ligation. After fully dissecting out the head from the portal vein and superior mesenteric vein venous branches, attention is turned to the superior mesenteric artery.
• The superior and inferior pancreaticoduodenal arteries can then be identified, ligated, and divided. The pancreas can then be skeletonized from the superior mesenteric artery attachments. The pancreas can then be removed and passed off the table for marking of the margins and sending specimens from the bile duct, duodenal, and uncinate margins. After the margins are confirmed, reconstruction is performed. The biliary enteric anastomosis can then be created using the distal end of the jejunum. An end to side anastomosis is performed from the distal common hepatic duct to the proximal loop of the jejunum. This anastomosis is performed in one layer using interrupted 5-0 PDS suture. The ligated falciform ligament can be wrapped around the biliary anastomosis; depending on if the pylorus-preserving technique was performed or the standard technique, the proximal stomach anastomosis can be performed.
• If pylorus preservation was done, the duodenojejunostomy could be placed 20 cm distal to the newly created biliary enteric anastomosis. If the standard technique was performed, then a gastrojejunostomy can be created 20 cm distal to the hepaticojejunal anastomosis using either stapled anastomosis or hand sewn with an inner layer of 3-0 PDS and outer layer of 3-0 silk suture. The anastomosis should all then be checked for leaking. A ray-tech can be placed around the posterior aspect of the biliary anastomosis to look for bile spillage. After confirming all anastomosis are intact and open, the decision can be made to place feeding access with either a gastrostomy tube or distal feeding jejunostomy tube. Closed suction Jackson pratt drains can then be placed in the areas of the newly created anastomosis with placement on the anterior abdominal wall. They can be sutured in place with 3-0 Nylon. 

Central Pancreatectomy

• A central pancreatectomy allows the surgeon to conserve pancreatic parenchyma if the given lesion is operable with this technique. Central pancreatectomy allows much more conservation of the pancreas with postoperative long-term diabetes outcomes, only being 11 to 12% versus 20 to 50% of distal pancreatectomy patients. The exocrine function is also maintained at a much higher rate with central pancreatectomy, with only 10% of patients requiring supplementation versus 27% of distal pancreatectomy patients. Central pancreatectomy also preserves the entire biliary anatomy and avoids splenectomy. Central pancreatectomy is not indicated for pancreatic cancer as margins that remain may harbor malignancy, and lymph node harvest is not as sufficient. Surgical intervention for central pancreatectomy is only reserved for benign or potential borderline lesions and is thus probably the least likely utilized pancreatic resection surgery. The distal pancreas must have 5 to 6 cm of remaining parenchyma. 

• After the entire pancreatic neck, body, and tail are exposed, the neck of the pancreas can be mobilized. The superior splenic vessels can remain intact and do not require ligation. Several of the small vessels running on the neck of the pancreas may need to be ligated for adequate mobilization of this area. The proximal portion of the pancreas can be transected using a stapler with a reinforced staple line. As with other pancreatic transections, the distal part of the pancreas can have two stay sutures placed to help control hemostasis before the transection occurs. The gland can then be transected with a scalpel or energy device. The margins are then sent immediately to pathology to confirm a negative margin. The distal remnant pancreas can then be drained either into the stomach or into the small bowel. If a pancreaticogastrostomy is the choice for drainage, then the pancreatic body must be mobilized off the splenic vessels for better mobilization to the stomach. The pancreas must be mobilized enough for the pancreas to be delivered into the stomach. This is done by making an anterior and posterior gastrotomy. The pancreatic remnant is then placed into the stomach without any added tension to either structure. The posterior stomach can then be sewn to the pancreatic parenchyma into the capsule with either 3-0 PDS or silk suture in a simple interrupted fashion or running technique. The anterior portion of the stomach is then closed in two layers with underlying PDS suture and silk for the outer layer. A drain is then left next to the newly created anastomosis. A jejunal limb can be used for the pancreaticojejunal anastomosis for the pancreatic remnant. The jejunum can be transected 15 to 20 cm distal to the ligament of Treitz. A limb of jejunum approximately 35 to 40 cm long can be passed through the mesocolon opening to lay beside the pancreatic remnant without any tension. The distal jejunum continuity can be restored with a jejunojejunostomy anastomosis. The pancreatic duct to jejunum anastomosis can be performed with an end to side anastomosis. The anastomosis can be created in two layers; the first layer is created by sewing the jejunal serosal layer to the pancreatic capsule in a running fashion. The pancreatic duct is sewn to the jejunum by first making a small enterotomy in the jejunum. The pancreatic duct is then sewn directly to the mucosa with either 5-0 PDS or vicryl. A small feeding tube can be placed through the jejunal wall and placed inside the pancreatic duct to help aid as a stent for the duct. The anterior pancreatic to jejunum anastomosis is then completed using a running 5-0 prolene suture. A drain is left near the anastomosis and pancreatic stump. The proximal pancreas can also be anastomosed to this portion of the jejunum if the stapled edge is felt to be too thick for a secure staple line or if it is thought this area may have a pancreatic duct stricture. This allows the head of the pancreas to drain and may save the patient from developing a pancreatic fistula if the stump were to break down. This anastomosis is performed in the manner as the previously created pancreaticojejunostomy.[13][14][15]

Distal Pancreatectomy

• When performing a distal pancreatectomy, the surgeon usually knows if this is being performed for a malignant process. If there is a malignant tumor of the distal pancreas, the spleen cannot be preserved. Suppose the resection is for a benign distal pancreatic lesion. The spleen can be preserved. We will discuss both techniques below. 

• Distal Pancreatectomy with splenectomy - Once the pancreas has been exposed via entry into the lesser sac by dividing the gastrocolic ligament as previously discussed, the splenic flexure and colon can be further mobilized. The exposure can be from a lateral to medial approach with mobilization of the pancreas and spleen from the retroperitoneum and vasculature with transection of the pancreas, or it can be performed with a medial to lateral approach with transection of the pancreas at the confluence of the superior mesenteric vein and splenic vein and then complete the dissection laterally. Either technique can be used for distal pancreatectomy. 

• The spleen can then be mobilized by taking down the splenocolic ligament to help further mobilize the splenic flexure. Gentle medial retraction can be applied to the spleen to aid in mobilization. The short gastric arteries can be ligated using an energy device, and the stomach can be further retracted superiorly and medially to the right upper quadrant. Of note, the surgeon may utilize a stapler for the division of the short gastrics near the gastroesophageal junction if there is not adequate space between the stomach and spleen to avoid the possibility of thermal injury to the stomach.  Once the entire distal pancreas and the splenic vasculature are completely visualized, pancreatic transection can be performed, ranging from the neck to the distal tail. If the transection will be performed on the neck of the pancreas, the middle colic vein is an excellent landmark for finding the superior mesenteric vein. The neck of the pancreas can then be carefully dissected from the retroperitoneal attachments, superior mesenteric vein, and splenic vein. The pancreas can then be resected using either a scalpel or a stapler device with reinforcement. If the scalpel technique is used, first place superior and inferior stay sutures on the pancreas to help aid with hemostasis. Once the pancreas is transected, the identification of the main pancreatic duct must occur. The end of the duct can then be oversewn using 3-0 silk sutures in a figure of eight technique. The remaining pancreatic parenchyma is then oversewn using several U stitches with pledgets. The splenic artery can then be ligated. Prior to ligation, the splenic artery can be temporarily clamped, and palpation of the common hepatic artery can be palpated to ensure that it has not been accidentally ligated. If pulsation is present in the hepatic artery, the splenic artery can be divided using a vascular stapler load or double ligated with a 2-0 silk or prolene suture. After splenic inflow is taken away, the spleen can be decompressed, and the remaining attachments to the splenic artery and vein from the pancreas can then be divided. The splenic vein can then be either ligated with 2-0 silk suture, or a stapler load can be fired across the vein. When ligating the splenic vein, care should be used not to leave the vein longer than needed as this can help prevent thrombosis of the splenic vein remnant. The thrombosis can migrate into the superior mesenteric vein and cause outflow issues with the possible compromise of the small bowel. The spleen can then be mobilized to the midline, and the remaining attachments are taken down. The specimens can then be passed off the operative field to be sent to pathology. The falciform ligament, which was ligated earlier, can be used to cover the ligated splenic artery stump and the distal pancreatic transection site. Hemostasis can be achieved. The decision to leave a drain is surgeon dependent. 

• Distal Pancreatectomy with Spleen Preservation - Can be performed when the known distal pancreatic mass is benign. The spleen should be preserved if possible to avoid asplenia and post-splenectomy sepsis. The surgical technique to manage spleen preservation can be performed in two different manners. The Warshaw technique involves avoiding ligation of the left gastroepiploic and short gastric arteries on the initial dissection. If the Warshaw technique is chosen, the splenic artery and vein can be ligated. Splenic infarction with necrosis is one of the most common complications after performance of the Warshaw technique, but late-onset left-sided portal hypertension can also be seen as well.[16] Another technique for splenic preservation involves diligent dissection. The ligation of the small splenic arteries and veins that supply and drain the pancreas with preservation of the splenic artery and vein has less postoperative end results of splenic infarction and formation of gastric varices.[17][18] The initial steps of the distal pancreatectomy are performed in the same manner. For preservation with intact splenic vessels, the pancreas is divided, and the splenic vessels can then be encircled using vessel loops. The small branches can then be individually ligated, and the splenic artery and vein can be divided using either a staple load or suture ligation. The transected pancreas can then be passed off the operative field. To perform the Warshaw technique, the vessels are divided at the transected portion of the pancreas and at the distal portion near the splenic hilum. The specimen is then passed off the field with the pancreas and vessels on the superior aspect. The spleen must be checked for signs of ischemia immediately after this technique. Adequate perfusion is usually confirmed with intraoperative ultrasound as well.

• Distal Pancreatectomy with islet cell autotransplantation - Over the last 10 to 15 years, this technique has become much more commonly performed after total pancreatectomy for chronic pancreatitis. Total pancreatectomy removes all endocrine and exocrine function from the patient. Autotransplantation allows the patient to have an endocrine function even after the removal of the pancreas. Patient selection and decisions on who will really benefit from autotransplantation are key factors that must be discussed. Patients must undergo testing to validate adequate islet cell number and function. There are multiple contraindications to performing total pancreatectomy with islet autotransplantation: if the patient has an active substance abuse, pancreatic cancer, or poorly controlled psychiatric illnesses. If the patient is determined to be a candidate for total pancreatectomy with islet autotransplantation, the transplantation can occur during the same operative intervention. After the pancreas is removed, it is placed on the back table for preparation. The pancreas is placed into ice-cold water with antibiotic solution and the preservation solution. The gastroduodenal and splenic arteries are then injected with a preservation solution. The pancreatic duct can then be cannulated on the table with an injection of a preservation solution with a mixture of different enzymes. The gland is injected until fully distributed throughout the parenchyma. The pancreas can then be cut into small 5 mm sections. The sections can then be placed into a Ricordi digestion chamber. The chamber can then be shaken. The chamber solution can then undergo microscopy for adequate islet cell count and application of human albumin with centrifugal treatment. The specimen can then be prepared for injection into the portal vein system. To avoid any portal vein thrombosis or portal hypertensive complications, the specimen can be injected with heparin running intravenously. The goal of this treatment is to have the patient remain insulin-free. Studies have shown that up to one-third of patients remain insulin-free while another one third will have a partial function of their islet cell transplantation. The overall goal of total pancreatectomy with islet autotransplantation is to relieve the patient of chronic pain and to reserve their endocrine function to avoid chronic insulin use.[19][20]

Trauma-Related Pancreatectomy

• Pancreatic injury can occur due to blunt or penetrating trauma. Surgical intervention usually depends on ductal injury and hemorrhage control in the operating room. CT imaging is of great importance for diagnosing pancreatic injuries. Patients can usually be managed non-operatively if a ductal injury can either be ruled out with MRCP or with stent placement via ERCP.[21]

• Pancreatic organ injury scale (AAST):

• Grade 1 - Hematoma- major contusion without duct injury, parenchymal loss, or a superficial laceration without duct injury

• Grade 2 - Hematoma- major contusion of the gland without duct injury tissue loss, or a major laceration without duct injury or tissue loss. 

• Grade 3 - Laceration with transection of the distal gland or parenchymal injury with duct injury

• Grade 4 - Laceration to the proximal gland to the right of the superior mesenteric vein with transection or parenchymal injury

• Grade 5 - Laceration with massive disruption of the pancreatic head

Management 

• As with any trauma-related injury to the patient, the overall goal is to control hemorrhage and avoid further gastrointestinal spillage into the abdomen. The surgeon must have complete exposure of the entire gland. This is described above for access to the lesser sac. A full Kocher maneuver should be performed to visualize the entire pancreatic head and uncinate process. If a large hematoma is noted around the C loop of the duodenum, an ng tube can be passed post-pyloric to help guide dissection. The majority of pancreatic injuries involve minor contusions, hematomas near or on the gland, and at times lacerations to the capsule. These injuries only require hemostasis and drain placement. Repairing a capsule laceration without duct injury can lead to pseudocyst formation. Drainage of the pancreas is usually better tolerated for the patient. The drains should be left in place for at least 10 days so that fistula formation can be recognized. 

• Grade 1 and 2 injuries can usually be managed with MRCP to look for ductal injury or ERCP with stent placement if duct injury is found. If a grade 1 or 2 is discovered while in the operating room, wide local drainage and hemostasis is the usual management. Grade 3 injuries are hard to differentiate from lower grade injuries. Nonoperative management of grade three injuries is controversial in the literature. Stenting has a role in management, but it is not the sole management. If the injury is found during exploratory laparotomy and there is a high probability of injury, but there is no obvious ductal involvement to the head, then wide local drainage should be the management approach. If the high probability of injury is noted to the body and tail can be treated with distal pancreatectomy. 

• Grade 4 injuries to the pancreatic head and neck are some of the most challenging to manage. If the identification of the duct can not be performed in this area, wide local drainage with post-op ERCP should be performed. If the injury to the proximal neck is found, you must consider the patient's overall medical history if known. This will determine if they can tolerate an extended distal pancreatectomy with resection of more than 80% of the gland. If a large destructive injury is noted to the head, wide local drainage should be performed and resuscitation to allow time for thought for the best overall reconstruction options for the patient. Discussion with an expert in the field is recommended. 

• Grade 5 injuries to the head of the gland are very tough to manage and carry heavy patient morbidity and mortality if not managed correctly. Pancreaticoduodenectomy (Whipple) is rarely indicated in a trauma setting. Patients in extremis in the operating room with pancreatic injuries should have damage control performed with hemorrhage control and then be taken to the surgical ICU for resuscitation. Indications for this to be performed are massive destruction of the pancreatic head, avulsion injury to the ampulla of Vater, or intrapancreatic bile duct or proximal pancreatic bile duct injury. When these injuries are found, they should be managed in a staged manner. The patient’s physiological status should be optimized prior to proceeding with a large reconstruction. 

• The main goal of managing the pancreatic injury is to identify if there is a pancreatic duct injury. The duct can be either oversewn or stapled. While in the operating room, if the patient's status allows further time, feeding access should be placed at the initial laparotomy.[22][23]

Complications

The following are the potential complications:

• Postoperative pancreatic complications can be some of the most feared complications in surgery. The complications can gravely affect the patient if not diagnosed and managed in a quick manner.
• Postoperative fistulas are one of the most common complications occurring after pancreatectomy. Each surgical procedure described above has a risk for the possible development of a fistula. Some reports have a fistula rate occurring as high as 20-60%. The majority of the reported fistulas are grade A and management consists of continued drainage as most of these types of fistulas will heal without other intervention. Occasionally a patient may need a percutaneous drain placed into a small fluid collection (grade B). Rare patients requiring ICU care for sepsis and multisystem organ failure of their pancreatic leak (grade C complications), but when recognized, need swift surgical intervention, which may end in completion pancreatectomy save the patient.  Pancreatic fistula is a serious complication and can greatly impact patient recovery and overall health.[24][25][26] Postoperative diabetes development s is another serious complication after pancreatic surgery if a large portion of parenchyma is removed. It usually occurs less than 10% of the time. Diabetes that occurs after total pancreatectomy is referred to as pancreatogenic diabetes. Total pancreatectomy may also lead to liver steatosis, exocrine insufficiency with steatorrhea, retinopathy, increased neuropathy, and increased cardiovascular disease.[27]
• Splenic infarction can occur after ligation of the splenic vessels during the Warshaw procedure. This at times leads to the development of an abscess. Ligation of the splenic vessels can also result in gastric varices formation.
• Delayed gastric emptying is a variable post-op complication that can occur in up to 50% of patients. It is diagnosed when there is significant nasogastric tube output. Delayed emptying can prolong the hospital stay and make the patient have a poor life quality until resolution. Prokinetics offer mixed results for potential relief of the motility issue. 
• An anastomotic leak from the newly created anastomotic sites is a major cause of postoperative complications. Multiple studies have been performed which show that regardless of the technique for the creation of the anastomosis there is still a large risk for a leak.[28]
• Intra Abdominal hemorrhage after pancreatic surgery can occur from multiple different etiologies. Early in the post-op course, it is likely due to the operative failure of hemostasis. The latter portion of the postoperative course is seen with pancreatic leaks causing erosion into a vascular structure or causing a breakdown to an anastomotic site.[29]
• Wound complications are also another complication that can occur following surgery. This is a broad topic as many patients have different pathologies but undergo pancreatic surgery. Patients with poor nutrition or those undergoing preoperative biliary stenting or other endoscopic biliary procedures have higher rates of wound complications and well as patients with diabetes and obesity.

Clinical Significance

Pancreatic surgical resections are a collective group of highly complex surgical procedures for multiple different diagnoses. The surgical resection that fits your patient's needs must be well thought out after accurately diagnosing the patient and their pancreatic lesion. The proper diagnosis and surgical technique can lead to excellent cure rates of both malignant and benign disease. Pancreatic surgery must be performed with excellent skill and attention to detail as the postoperative complications carry a heavy toll on the patient's hospital course and quality of life. Pancreatic surgery has had many advancements over the course of the last several years. Minimally invasive techniques are becoming more popular, which helps to decrease overall pain, hospital stay, and the patient can return to work faster.

Enhancing Healthcare Team Outcomes

Pancreatectomy may be performed laparoscopically or with an open technique and is most often indicated in the presence of benign or malignant tumors, chronic pancreatitis, and pancreatic trauma. Due to the unique anatomy and complex vasculature of the pancreas, surgical excision of the pancreas is extremely difficult. To improve the decision-making process, having interprofessional team meetings, including surgeons, anesthesiologists, nurses, and other OR personnel, is always advised.

Preoperative preparation is key in order to have successful pancreatic surgery. Intraoperatively, all team members must be in constant communication and adhere to the preoperative plan as well as monitor the patient’s vital signs to assess the need for blood, fluid, or vasopressor administration. Assessment of the patient continues in the postoperative period in intensive care units as this is when many surgical patients experience hemodynamic issues and also experience increasing amounts of pain as they awaken from anesthesia. As always, interprofessional communication enhances healthcare team outcomes and decreases morbidity and mortality.

Nursing, Allied Health, and Interprofessional Team Interventions

As mentioned above, an interprofessional team is needed in the partaking of a pancreatectomy. This team must always consist of the surgeon, an anesthesiologist or nurse anesthetist, surgical assistants or surgical scrub technicians, OR nurses, and other personnel, including the ICU nurses and doctors that will manage the patient postoperatively. While the surgeon will be the one to perform the actual pancreatectomy, the anesthesia specialist is responsible for keeping the patient asleep and minimizing the pain and discomfort that may be caused by the procedure. OR nurses and surgical scrub techs are strictly in charge of assisting the surgeon with whatever he or she needs, such as handing them instruments or repositioning the patient to better their view and access to the pancreas. ICU nurses will manage the patient vital signs by administering blood, fluids, and potentially vasopressors as in OR, but also manage the patient’s pain as they will be awake and especially in the case of total pancreatectomy close blood glucose monitoring is critical.

Nursing, Allied Health, and Interprofessional Team Monitoring

Each and every team member is responsible for monitoring the patient and being prepared for possible complications of the pancreatectomy. Whether laparoscopic or open, many of the complications are the same. Patients are at risk for the development of pancreatic fistula, postoperative diabetes, and splenic infarction. All of these complications, if not recognized and treated early, can severely affect the recovery of the patient. As the development of a pancreatic fistula can lead to malnutrition, skin excoriation, and infection, it is important to monitor the drain output, blood pressure, heart rate, respiratory rate, and white blood cell count, especially in the case of infection. While postoperative diabetes can also occur from pancreatectomy, it is essential to monitor blood glucose levels and assess the need for insulin as the patient may become insulin-dependent for life. In this case, diabetic education is extremely important both in the preoperative and postoperative settings. When blood flow to the spleen is compromised, the spleen can cause infarct and die, leading to infection. Signs and symptoms of infection are the key elements that all team members should be aware of.