Complications of Gastric Bypass and Repair
Robert B. Lim
Introduction
The Roux-en-Y gastric bypass (RYGB) is one of the most commonly performed surgical procedures today in the United States. With around 30% of the world’s total population being obese, combined with the fact that the surgery has become safer and its outcomes have improved, there doesn’t seem to be a foreseeable decrease in the near future of the surgery’s exponential growth. At its current pace, a full 700 million people by the year 2015 will have a body mass index (BMI) over 40 kg/m2. Such a BMI significantly reduces life expectancy and is associated with many weight related co-morbidities. Consequently bariatric surgery is no longer seen as just a cosmetic weight loss procedure but rather as a way to manage the metabolic derangement of obesity. Currently the most effective way to treat obesity is with surgery. It is clear now that the best chance to treat the obesity-related risk of early mortality is with surgical care of this metabolic disease. Gastric banding and the sleeve gastrectomy are other forms of weight loss surgery (WLS) that are gaining popularity; and while those operations are associated with less mortality than the RYGB, they don’t seem to have the same amount of weight loss or co-morbidity resolution as does the RYGB. Moreover, there are expanding indications for the use of the RYGB, to include pediatric patients to improve outcomes from other surgeries like hip replacement and organ transplant, and for type II diabetes in the patients whose BMI would heretofore not qualify them for surgery. Indeed it is likely, therefore, that most general surgeons during their career will encounter a patient who has undergone an RYGB.
Unfortunately, there is no universal acceptance of the best way to perform this procedure. No one truly knows, for example, the optimal pouch size or roux limb length for superior weight loss with the least amount of complications. Fortunately, while the total number of procedures has increased over the past decade, the incidence of death and major complications has significantly decreased. The American College of Surgeons (ACS) and the American Society of Metabolic and Bariatric Surgeons (ASMBS), using guidelines like that of the Betsy Lehman Center recommendations on weight loss surgery (WLS), have gone to great lengths to define the criteria and benchmarks that mark safe practices and establish Centers of Excellence for those providers and institutions who want to perform WLS. Centers of Excellence, in turn, rely on and report their outcomes on the National Surgical Quality Improvement Program (NSQIP) database. In this manner, the bariatric societies are better able to police themselves, define exactly what the goals are for surgical weight loss, and set up multidisciplinary teams and resources to help prevent and manage the complications of surgical weight loss as well as provide lifelong support to the patient for the unique problems of bariatric surgery and obesity management (see Table 1).
The complications discussed in this chapter are the ones that historically have caused some providers to be fearful of managing RYGB patients (see Table 2). It is important to note, though, that with thoughtful management using a multidisciplinary team and early recognition of the complications of RYGB, the rates of mortality, major complications, hospital readmission, and prolonged hospitalization have all substantially decreased over the past 5 years. Because of this, the use of RYGB is even more likely to increase and the need for general surgeons to help identify and manage these complications will also increase.
Table 1 Elements of a Multidisciplinary Surgical Weight Loss Team | ||||||||||||||||||||
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Table 2 Complications of Roux-en-Y Gastric Bypass | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Early Complications (Within 30 Days)
Gastrointestinal Leak
Open or laparoscopic, handsewn, circular stapled or linear stapled, anastomotic leaks occur at a rate of 0.7% to 5.1%. It is the most feared complication of the RYGB, not just because it is the most common reason bariatric surgeons face legal action. The presence of a leak can unfortunately result in a mortality rate as high as 30% and can increase morbidity up to 55%. The incidence of gastrogastric fistula, gastrointestinal bleeding, thrombo-embolic events, wound infection, respiratory failure, and mortality each were at least four times more likely to happen in those patients who had a leak postoperatively. Most leaks occur within the first 28 days after an operation, with the majority of these occurring in the first 7 days. With revisional surgery, the rate can be as high as 35%. Tissue ischemia is the most prominent risk factor for leaks. They can occur if there is tension from the roux limb on the anastomosis or if the vascular supply of the gastric pouch or roux limb is compromised during dissection. Leaks are also more likely to occur in male patients over the age of 50 and by bariatric surgeons who have performed less than 75 procedures.
Patients with leaks may be asymptomatic. The most specific physical signs of a leak are sustained tachycardia above 120 and respiratory compromise. But patients can also present with abdominal pain, nausea, diaphoresis, fever, and a “feeling of doom.”
In clinically stable patients with sustained tachycardia, the management can begin with a workup for the common causes of postoperative tachycardia to include myocardial infarction, pulmonary embolism (PE), surgical bleeding, and hypovolemia. Anxiety, pain, and rebound tachycardia should also be considered as possible etiologies. Evaluation of the tachycardia, though, should be completed in an expeditious manner.
A leak can be confirmed by an upper gastrointestinal (UGI) series or a computed tomography (CT) scan with oral contrast given just before the study. The UGI studies are done typically first using gastrografin to identify larger leaks, then with thin barium to detect smaller leaks. CT scans have the advantage of being able to identify associated fluid collections, internal hernias, and abscesses. Unfortunately, neither study is particularly specific for identifying leaks at the gastrojejunostomy; and they are unreliable for detection of a leak at the jejunojejunostomy. Because of the associated major complications of a leak and the unreliability of radiologic studies, if tachycardia rate of more than 120 beats/min persists despite a normal workup, it is prudent to proceed with surgical exploration despite an otherwise “good” clinical picture.
Some small, contained leaks can be treated without an operation, with management consisting of nasogastric decompression, “nothing by mouth” (NPO) status, total parenteral nutrition (TPN), and percutaneous drainage of the leak. When the drainage output decreases, a leak study can be repeated and if none is found, then enteral feeding can be started.
If the patient becomes hemodynamically unstable, or their tachycardia is accompanied by respiratory distress, the appropriate therapy is usually urgent exploration. Leaks can be found intra-operatively by using insufflation, or methylene blue and endoscopy may also help. If a leak is found, primary repair should be done, along with an abdominal washout and wide drainage. The use of biologic sealants has not proved to be an effective way to treat leaks. The repair of the leak should be done after freshening the edges of the leak and in two layers, with the inner layer being absorbable interrupted sutures and the outer layer being permanent suture via interrupted seromuscular bites. One should probably avoid a running suture because when the edema subsides, the running suture may become loose. If the leak cannot be found, then it is reasonable to simply wash out, debride, and widely drain the area in an effort to contain the leak. One should also consider placement of a nasogastric tube past the gastrojejunostomy anastomosis to help control the leak and placement of a gastric tube in the remnant stomach for delivery of postoperative nutrition and medications. Postoperatively, systemic inflammatory response syndrome (SIRS) should be anticipated and the patient will most likely need management in an intensive care setting.
In any situation, it is most important to have a high clinical suspicion for a leak. A negative exploration is far less damaging than a leak that is allowed to continue on for days.
Bleeding
Hemorrhage after RYGB occurs 0.8% to 4.4% of the time. The most common site is usually at the staple lines, and the use of fibrin sealants or staple line reinforcers at the time of the initial operation may have some benefit. If the patient presents with hematochezia,
hematemesis, or even melena, then intraluminal bleeding should be suspected and endoscopy may help diagnose and treat the hemorrhage. Extraluminal bleeding may present with increased bloody drainage output if drains are used or more subtly with an ileus. Bleeding that occurs within several hours after the operation is more likely to require operative intervention than bleeding that occurs several days later. If there are signs of hemodynamic instability, it is more appropriate to proceed quickly with operative intervention to include intraoperative endoscopy rather than delay treatment with studies to localize the source.
hematemesis, or even melena, then intraluminal bleeding should be suspected and endoscopy may help diagnose and treat the hemorrhage. Extraluminal bleeding may present with increased bloody drainage output if drains are used or more subtly with an ileus. Bleeding that occurs within several hours after the operation is more likely to require operative intervention than bleeding that occurs several days later. If there are signs of hemodynamic instability, it is more appropriate to proceed quickly with operative intervention to include intraoperative endoscopy rather than delay treatment with studies to localize the source.
When bleeding does occur, 85% of the patients can be successfully managed without surgery. Initial management includes fluid resuscitation, discontinuation of any anticoagulation, correction of an abnormal coagulation profile, and, possibly, red blood cell transfusion. Hypotension, tachycardia, and a decreasing hematocrit despite the aforementioned management, though, require endoscopic and/or surgical intervention.
Deep Venous Thrombosis (Dvt)/Pulmonary Embolism (Pe)
PE accounts for 50% of the deaths in the perioperative period, making it the most common cause of mortality after an RYGB. The rates of DVT after RYGB can be as high as 1.3%, while PE can occur up to 3.0% of the time. Obesity is believed to be a prothrombotic state, and thus RYGB patients should be considered at high risk for the development of DVTs and PEs.
Unfortunately, there is no quality data identifying the best forms of DVT/PE prophylaxis, especially when considering the risk of surgical bleeding complications. Moreover, there is no consensus in the practice of experienced weight loss surgeons. The use of anticoagulants with sequential compression devices starting before the operation and continuing until the patient is ambulatory is perhaps most common. For patients at increased risk for DVT/PE, extended prophylaxis should also be considered. The use of inferior vena cava (IVC) filters in patients, who are at the highest risk for a DVT/PE, has not proved definitively to be superior to current anticoagulation strategies. Consultation with a hematologist and a vascular surgeon to help prevent venous thromboembolic events should be considered in the patients with the highest risk.
Cardiovascular Complications
Cardiovascular events are the second most common cause of death in the postoperative period, accounting for 33% of such deaths. Fortunately, the overall incidence of a cardiac ischemic event after WLS is less than 1%. Still, RYGB candidates should be evaluated preoperatively for their cardiovascular risk and this may include consultation with a cardiologist. The patient’s long-term cardiac risk, on the other hand, does reduce with successful weight loss and is considered one of the benefits of bariatric surgery.
Pulmonary Complications
The rate of pulmonary complications has decreased significantly since the early 1990s. Atelectasis is still relatively common after RYGB with a rate of 8.4% after laparoscopic surgery, and this is probably higher after open procedures. But the incidence of other pulmonary complications, like pneumonthorax, pneumonia, pleural effusion, and respiratory failure, is less at 4.5%. The risk factors for pulmonary complications are those patients with chronic lung disease, those on Medicare, male gender, and patients over the age of 50. Early ambulation, use of incentive spirometry, and recognition of patients with sleep apnea can help reduce the incidence of these complications. One should be suspicious of pulmonary complications and be ready to provide ventilatory support with an experienced anesthesia provider, should the need arise, because the obese patient can be very difficult to intubate. Despite its decreased incidence, respiratory failure remains the third most common cause of mortality after RYGB. In the long-term, persistent vomiting or reflux after RYGB can be due to a stenosis, and these patients are at increased risk for aspiration pneumonia.
Late Postoperative Complications (After 30 Days)
Stenosis
Stenosis or an anastomotic stricture occurs at a rate of 8% to 19%, regardless of surgical technique, but they seem to be more common after stapled anastomoses, especially at the gastrojejunostomy. They usually occur within the first few months after surgery; and early on, patients may complain of nausea, pain, and regurgitation of saliva. If the stenosis progresses, it can lead to vomiting and the inability to tolerate oral intake. Stenosis is thought to be caused by ischemia at the anastomostic site or by tension on the Roux limb, but it can also be a consequence of marginal ulcers. If that is the case, then a stricture can occur at any time after surgery. If the stenosis is significant enough, the patient may require hospitalization, intravenous fluid resuscitation, and correction of nutritional deficiencies.
Endoscopic balloon dilation should be the first step in correction of this problem; and, while highly successful, some patients may require more than one procedure. There is also a small risk of perforation. Moreover, repeated failed attempts may result in swelling at the anastomotic site, making successful dilation by another provider more difficult. If possible, therefore, patients should be transferred to a facility whose endoscopists are well-versed with dilation. If dilation fails to treat the stenosis, then one should consider revising the anastomosis; but again, ideally, a surgeon with experience in revisional weight loss procedures should be the one to do this. If the stricture occurs at the jejunojejunostomy, then it is less likely to be amenable to endoscopic repair, and surgical revision should be considered.
Gallstone Formation
Gallstones can develop in up to 38% of the patients after RYGB. The incidence of stone formation can be reduced to about 2% with the use of ursodiol, which is generally recommended for use until about 6 months after the operation. There is no data that suggests use beyond this time period. The development of gallstones is multifactorial and can be related to vagus nerve disruption during surgery or changes in calcium concentration and bile salt/cholesterol ratio due to the malabsorption aspect of the surgery. Because gallstone incidence is so high, some surgeons elect to remove the gallbladder during the time of their weight loss operation, especially if stones are seen preoperatively.
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