Pancreatic Resections

Malignancy is the most frequent indication for pancreatic resection. When the malignancy is located in the head of the pancreas, a pancreaticoduodenectomy (Whipple procedure) is typically performed, which involves an en bloc resection of the pancreatic head and entire duodenum. Four anastomoses (gastroenteric, bilioenteric, enteroenteric, and pancreaticoenteric) are required to reestablish gastrointestinal (GI) tract continuity. The degree of physiologic perturbation secondary to an uncomplicated pancreaticoduodenectomy is moderate, primarily involving fluid shifts between intra- and extravascular compartments. Self-suctioning Jackson-Pratt (JP) drains are usually placed adjacent to the pancreatic and biliary anastomoses allowing rapid identification of an anastomotic leak. Stents may be placed through the anastomoses to promote patency. Major complications are often related to the integrity of the anastomoses and usually occur between 5 and 10 days postoperatively. It is important that the intensivist know the specific location of each drain or tube, all of which should be illustrated in the patient’s record.

Mortality rates in centers performing more than 18 to 24 cases per year are less than 5% as compared to 10% to 15% for centers with < 5 cases per year.

Postoperative bleeding occurs in 5% to 7% of patients and is the most frequent complication that necessitates an immediate return to the operating room. Although bleeding is frequently considered to be an immediate postoperative complication only, in reality about half of major bleeding episodes occur after the first day. These late bleeds may be associated with a pseudoaneurysm and consideration should be given to assessing and managing those using angiographic techniques.

Distal pancreatectomy for tumors in the tail of the pancreas does not typically require a pancreaticoenteric anastomosis as exocrine secretions continue to empty antegrade into the duodenum. Because the vasculature of the spleen is intimately associated with the tail of the pancreas, the spleen and distal pancreas are most often removed en bloc. Endocrine insufficiency is uncommon with the Whipple procedure or distal pancreatectomy. However, patients who undergo total pancreatectomy will immediately become diabetic. These patients also require pancreatic exocrine supplementation to aid food digestion once enteral nutrition is started.

Hepatic Lobectomy

Resection of 50% or more of hepatic parenchyma may result in hyperbilirubinemia, jaundice, hypoglycemia, hypoalbuminemia, hypophosphatemia, and hypokalemia. Jaundice and hypoglycemia are the most common sequelae of large hepatic resections. Jaundice usually peaks between 3 and 4 days postoperatively and should be investigated if it persists beyond 10 days. Hypoglycemia is often severe enough to warrant intravenous infusion of 10% dextrose. Liver regeneration involves rapid cell division as early as 24 to 72 hours after resection. This is an adenosine triphosphate (ATP)–dependent process that often results in severe hypophosphatemia and may cause reversible cardiac dysfunction, hypoventilation, or impaired immunity. Monitoring and aggressive repletion of serum phosphate levels are necessary to prevent such complications. The most serious complication of major liver resections, however, is fulminant hepatic failure—that is, hepatic metabolic and synthetic failure. This occurs more frequently in patients with underlying primary liver disease (e.g., cirrhosis) or those who have been exposed to hepatotoxic drugs. Drug metabolism, anesthetic clearance, and the production of clotting factors II, VII, IX, and X will be significantly altered after large hepatic resections. Large infusions of plasma are often required to prevent bleeding complications early on. Although hepatic clearance of lactate may be impaired in these patients, persistently elevated lactate levels in the posthepatectomy patient should be considered indicative of hypoperfusion until proven otherwise.

Esophagogastrectomy

There are three principal open surgical approaches to esophageal resection and the postoperative course and associated complications differ depending on which technique is employed. Common to all of the procedures is an upper midline laparotomy incision through which the distal esophagus and proximal stomach are mobilized. After resection of the diseased portion of the esophagus, GI continuity is restored by anastomosing the tubularized stomach to the proximal esophagus. This anastomosis may be accomplished either through a thoracotomy or a left cervical incision depending on the extent of the resection. In general, complications following esophageal resection are more common than in other abdominal or thoracic operations, occurring in 10% to 25% of cases. Pulmonary complications may be related to the incisional pain from the thoracotomy or to loss of the lower esophageal sphincter, which predisposes the patient to aspiration of gastric contents. Many patients with esophageal carcinoma present initially with malnutrition and chronic obstructive airway disease as comorbid conditions that complicate the postoperative care. Pleural effusions are common after these procedures and occasionally require chest tube placement to maximize lung inflation. The most feared surgical complication after esophagectomy is an anastomotic leak, which occurs more commonly in cervical anastomoses than thoracic anastomoses. Whereas a leak occurring from a cervical anastomosis is usually well tolerated and easily managed, leakage from intrathoracic esophageal anastomoses often leads to mediastinitis and is associated with a higher mortality rate. Frequent assessment of the drains and wound is imperative to help identify early signs of anastomotic failure. Persistent tachycardia is a sensitive, though not specific, indicator of anastomotic leak. A change in the quality or quantity of drain effluent or the development of wound cellulitis can be an early harbinger of a leak.

Intestinal and Reoperative Abdominal Surgery

Because reoperative abdominal surgery is frequently performed to treat intestinal obstruction, these topics are presented together. Physiologic derangements, such as severe dehydration, contraction alkalosis, hypokalemia, and intravascular fluid redistribution, frequently accompany intestinal obstruction. Reasonable preoperative attempts to correct these abnormalities are warranted to avoid substantial postoperative problems. Reoperative abdominal surgery may be prolonged and may involve significant blood loss. It is not uncommon for an extensive lysis of adhesions to take between 4 and 8 hours and for the bowel to be drained of several liters of luminal fluid. Postoperative intra-abdominal infection or fistula formation may occur because of iatrogenic enterotomies or anastomotic leaks. In general, the morbidity following surgery for intestinal obstruction approaches 25% to 30%. Advanced age, delay in operative intervention, and other comorbid conditions have been shown to be associated with increased complication rates. Malignant obstruction and obstruction caused by radiation enteritis also result in higher morbidity and mortality rates. Massive small bowel resection may be required if a large portion of the intestine has been infarcted. If this is necessary, short-gut syndrome (usually defined as less than 100 cm of remaining small bowel in the presence of a competent ileocecal valve) may result.

Abdominal compartment syndrome (ACS) may occur in the postoperative setting when the abdominal fascia is closed but the viscera continue to swell secondary to ongoing resuscitation and inflammation. In such cases, reopening of the incision is often necessary with eventual closure days to weeks later.

Fluid Management

Fluid losses during abdominal surgery are proportional to the extent of surgical dissection, length of operation, blood or extravascular fluid lost during surgery, and presence or absence of infection or fever. Although formulas exist that attempt to define “ideal” maintenance fluids for patients undergoing major abdominal surgery, they are based on an estimation of the degree of evaporative or insensible losses associated with laparotomy. For a standard midline incision, this is usually estimated to be 1 liter per hour while the abdomen is open. This is only an approximation, however, and is not a substitute for fluid management guided by urine output, estimated blood loss, acid-base status, hemodynamic data, and clinical assessment of perfusion (Chapter 86).

Like other patients undergoing major surgery, patients undergoing major abdominal surgery sustain a stress or inflammatory response that causes fluid redistribution from the intravascular to the extravascular fluid compartment (the so-called third space) (Chapter 86). The presence of peritonitis may add dramatically to fluid loss into the peritoneum both intraoperatively and postoperatively.

Glomerular filtration rate decreases as the intravascular volume declines. This effective hypovolemia along with elevated levels of circulating catecholamines, aldosterone, and antidiuretic hormone (seen in the surgical stress response) enhances tubular resorption of Na⁺ and water in an effort to maintain intravascular volume.

Postoperative fluid management is best approached by considering maintenance fluids separate from all other fluid requirements. Early in the postoperative course, patients require a maintenance IV fluid rate that is generally 1 to 2 mL/kg/h. These fluids should be isotonic crystalloids unless salt restriction is indicated such as in cirrhotic patients. Controversy exists as to whether maintenance fluids in the immediate postop period ought to contain dextrose. Supplemental fluids, including those required to replace measured and insensible losses, should be administered as needed in response to measured physiologic abnormalities such as hypotension, oliguria, low cardiac filling pressures, and so on. The choice of crystalloid or colloid depends on the resuscitative philosophy of the intensivist. Too aggressive of a volume resuscitation may contribute to or cause profound tissue edema. As this edema progresses in various organs it can cause decreased bowel motility, pulmonary congestion, impaired wound healing, and decreased mobility from limb edema. A large randomized, prospective trial in a heterogeneous ICU population demonstrated no difference in 28-day outcomes between patients resuscitated with crystalloid versus colloid.

Measured losses include blood or ascites from drains and GI contents from nasogastric (NG), intestinal, or pancreaticobiliary tubes and stomas. Unmeasured losses include ongoing third space losses and evaporative losses resulting from fever and open wounds. Use of abdominal vacuum dressings in patients whose abdomens have been left open allow accurate measurement of abdominal fluid. Because a precise determination of insensible loss may be difficult, monitoring surrogates of end-organ perfusion (e.g., urine output) and acid-base status plus hemodynamic monitoring are recommended to guide fluid replacement therapy accurately (Chapter 86, Figure 86.3 and Tables 86.3 and 86.4).

Pain Control

Appropriate and effective pain management can help prevent postoperative pulmonary complications and decrease demands on the cardiovascular system. Historically, parenteral opioids have been the mainstay in providing postoperative pain relief (Chapter 87). Patient-controlled analgesia delivered parenterally or locally via subcutaneously placed catheters has been shown to be more effective than intermittent opioid dosing by care providers. Caution must be exercised when continuous or basal rate patient-controlled opioids are used, however, as the incidence of respiratory depression is higher than with intermittent dosing alone.

Neuraxial analgesia has emerged as the preferred method of pain control for patients undergoing major abdominal operations (Chapter 87). This method allows delivery of opioid, local anesthetic, or both directly to receptors surrounding the spinal cord. Because much lower serum concentrations of opioid result, less respiratory and central nervous system depression is observed. Active participation by patients in their own respiratory care—for example, performing deep breathing exercises with an incentive spirometer and coughing—is crucial in the postoperative period. Patients with epidural analgesia have been shown to more easily and effectively participate in these postoperative respiratory maneuvers and, as a result, can be mobilized earlier. Complications of epidural analgesia are rare and include infection, bleeding into the epidural space, postspinal headaches, and hypotension (Figure 87.2).

Nonsteroidal anti-inflammatory drugs are also useful in postoperative pain management because they have no respiratory or central nervous system depression. Some can be administered parenterally (ketorolac or ibuprofen) in patients who are receiving nothing by mouth.

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