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Nurse Practitioner:
doi: 10.1097/01.NPR.0000357248.01247.1e
Bonus Content: SURGICAL CARE

Bariatric surgery: Putting the squeeze on obesity

Budd, Geraldine M. RN, CRNP, FNP-C, PhD; Falkenstein, Kathleen RN, CRNP, PNP-C, PhD

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At Drexel University, Philadelphia, Pa., Geraldine M. Budd is an assistant professor of the doctoral program, and Kathleen Falkenstein is an assistant professor, College of Nursing and Health Professions.

The prevalence of obesity is increasing in the United States and globally due to an environment that encourages large portions of energy-dense food and reduced levels of physical activity.1,2 Currently, 32.2% of American adults are obese.1 In recent years, severe and morbid obesity in adults increased fourfold and fivefold, respectively, while childhood obesity tripled.3 Obesity is associated with multiple comorbid conditions, including type 2 diabetes, hypertension, heart disease, sleep apnea, joint impairment, increased inflammatory markers, cancers, and multiple psychosocial impairments.4 The risk of disease and mortality rises with increasing levels of body mass index (BMI). Extreme obesity is of particular concern, as multiple and serious negative effects occur in the cardiovascular, respiratory, metabolic, musculoskeletal, urinary, and reproductive systems.3 Obesity is calculated using BMI and includes three categories: class 1 (between 30 and 34.9 kg/m2), class 2 (between 35 and 39.9 kg/m2), and class 3 obesity (greater than 40 kg/m2).5

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Surgical treatment of obesity is accepted as a definitive therapy.6-8 From 1993 to 2004, the number of weight loss surgeries performed in the United States increased by 100%.9 When compared to behavioral and pharmacologic treatment of obesity, bariatric surgery (BS) offers significantly more weight loss, improvement in comorbidities, and reduced mortality.5,8,10-12 The increasing frequency of BS requires that NPs be knowledgeable about the risks and benefits of the surgery and be able to provide long-term management of these patients once the immediate postoperative period is over.

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Common procedures

Four main bariatric procedures are currently available (see Bariatric surgical procedures). The procedures fall into two categories: (1) restrictive types that reduce the size of the stomach, slow gastric emptying, and produce early satiety, and (2) malabsorptive procedures that divert food from a large portion of the digestive tract. There are different types, methods, and complications of each procedure (see Types of BS). The restrictive and malabsorptive Roux-en-Y gastric bypass (RYGB) and the restrictive laparoscopic adjustable gastric banding (LAGB) are most common in the United States. Less commonly performed procedures include vertical banded gastroplasty and primarily malabsorptive biliopancreatic diversion (BPD).

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Surgery criteria

Indications for BS include patients with a BMI of 40.0 kg/m2 or greater or between 35.0 and 39.9 kg/m2 with comorbidities. Patients with a BMI less than 35 kg/m2 and conditions that could be ameliorated or improved with significant weight loss may be considered possible candidates, despite the lack of data substantiating risk-to-benefit ratio.19 Candidates should be motivated, well informed, and have acceptable operative risks.20 Selecting appropriate patients and matching them with the most appropriate type of surgical procedure should be a priority, as decisions were historically based on insurance coverage or ability to pay, patient preference, or the surgeon's ability to perform one operation or another.21

In all cases, BS should be considered only after the failure of a comprehensive nonsurgical weight loss program that integrates diet, exercise, and behavioral modification.9,20 Although behavioral and pharmacological programs typically result in only 3% to 10% loss of body weight, the response increases with the duration of the treatment. Even a small amount of weight loss can demonstrate health benefits.6 Prior to surgery, candidates should undergo medical, surgical, psychiatric, and nutritional assessment so that severity of disease, risk for complications, motivation for behavior change, and nutrition education needs can be analyzed.

BS should not be performed in adolescents until both skeletal and developmental maturity is achieved. Additionally, adolescent surgeries should only be performed by surgeons who have extensive experience with such treatment in adults and a multidisciplinary team that possesses pediatric skills related to surgery, dietetics, and psychological management.22 The practitioner must balance the risk-to-benefit ratio before considering surgery in the older adult. In patients over 60 years of age, the primary objective of surgery is to improve quality of life, as the surgical procedure alone is unlikely to increase lifespan.

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Effectiveness

Weight loss after BS depends on the procedure and outcome. Overall, the greatest weight loss is seen after 1 year. Thereafter, weight increases to some degree.8,10,12,16,23,24 The Swedish Obese Subjects (SOS) study found that after 10 years, the average weight loss from baseline was 25% after gastric bypass, 16% after vertical banded gastroplasty, and 14% after gastric banding. When compared with a control group, patients in this study had lower incidence of diabetes, hypertriglyceridemia, and hyperuricemia. The study demonstrated an overall mortality reduction of 24.6%.24 In another study, a 50% overall reduction in mortality compared with control subjects was reported.11 Cause-specific mortality was reduced by 94% for diabetes, 71% for coronary artery disease, 62% for other circulatory diseases, and 55% for cancer.

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Postoperative complications

While BS is relatively successful, it is a technically difficult surgery that can be associated with a number of complications.25 Major complications occur in approximately 10% of surgeries.13,21,25

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Respiratory complications

Analyses of large population-based databases have consistently found respiratory disorders to be the most frequent complications of bariatric procedures.26 Unrecognized obstructive sleep apnea (OSA) is thought to influence peri- and postoperative morbidity and mortality.27 Postoperative respiratory complications can result from the central effect of pain medications weakening the pharyngeal muscles. In an obese patient, this may cause airway collapse and mimic a sleep apneic event. Thus, all patients must be preoperatively screened for OSA. If diagnosed, continuous positive airway pressure should be used postoperatively. Atelectasis, which can further reduce lung compliance and result in the development of postoperative pneumonia, should be prevented with early ambulation and incentive spirometry. Laparoscopic procedures typically produce less respiratory complications, as they are associated with less postoperative pain, decreased opioid use, and earlier ambulation when compared with open procedures.27

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Thrombophlebitis and pulmonary embolus
Figure. Bariatric su...
Figure. Bariatric su...
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Due to increased femoral and iliac vein stasis occurring during the procedure, laparoscopic bariatric procedures have a relatively high risk for venous thromboembolism.27 In all procedures, the presence of OSA may further increase the risk of thromboemboli because of associated polycythemia. Prevention includes evaluation for preoperative inferior vena cava filter placement, intraoperative heparin infusions, sequential compression devices, prolonged postoperative anticoagulation, and postoperative warfarin.27

Pulmonary embolus occurs in 1% to 2% of BS cases, producing a mortality of 20% to 30%.26 Patients present with profound hypoxia, hypotension, and signs of sepsis. Treatment is to rule out other abdominal complications and immediately begin anticoagulation therapy.13

Table. Types of BS...
Table. Types of BS...
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Abdominal pain

Leaks of the anastomosed site or staple line are the most common cause of postoperative (up to 7 to 10 days) abdominal pain. Some patients may not have abdominal pain, but present with tachycardia as the only indicator of a suspected leak.13,25,28 In patients undergoing LAGB, the most frequent complications are band malfunction or malposition. In patients undergoing RYGB, the complications are anastomosis (leaks, strictures, ulcers), bowel mobilization (strictures, adhesions, internal hernia), or portal vein injury. Early suspicion of a leak after RYGB or BPD/DS should prompt an urgent radiologic evaluation including a barium swallow or abdominal computed tomography (CT) scan.25 A large case series of 63 patients with leaks after RYGB reported that most were not detected by CT imaging and required surgery (63%), with a morbidity and mortality of 53% and 10%, respectively.29 Therefore, there is a very low threshold for urgent reexploration.13,25,26,29

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Bleeding

Bleeding in the early postoperative period (72 hours) is usually due to either an intraoperative complication or anastomotic ischemia.28 Endoscopy should be avoided postoperatively, as transient obstruction from a clot at the jejuno anastomosis site increases the risk of perforation at the gastric anastomosis or remnant.25,28

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Wound complications

Laparoscopic approaches to BS substantially reduced the incidence of wound infections. Fascial dehiscence, however, occurs in up to 1% of patients and is managed surgically. As reapproximation has a high failure and complication rate, mesh repairs are performed.26 Wound infections are treated by opening the wound and allowing it to heal by secondary intention.28 If cellulitis occurs, antibiotics are necessary.

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Stenosis/stricture

Stenosis post-RYGB may occur at anastomotic sites. These partial obstructions may be treated with endoscopic balloon dilation; however, there is a 2.1% perforation rate.25 Stenoses that occur beyond 2 months are usually due to marginal ulceration. Reducing risk factors (avoiding corticosteroids, NSAIDs, smoking) and treating with proton pump inhibitors may reduce ulcers and prevent restenosis.25 For narrowing associated with LAGB, balloon deflation may help ease stenosis without substantially increasing the lumen diameter.30 Irreversible stenosis associated with LAGB is almost always a result of band slippage or erosion. Revision or removal of the band is generally recommended.

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Long-term complications

The most common long-term complications found in postoperative BS patients are abdominal pain, diarrhea, suboptimal weight loss, nutritional deficiencies, and psychosocial maladjustments. Although more common in malabsorptive/restrictive RYGB and procedures that are strictly malabsorptive, clinicians should be aware of those patients who are at highest risk and monitor all bariatric postsurgical patients closely.

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Abdominal pain

Right upper quandrant abdominal pain, dyspepsia, or nausea after eating are the most common presenting symptoms with symptomatic cholelithiasis. Most closely associated with the early and rapid period of weight loss, this problem occurs in 3% to 50% of patients who undergo BS.9,25 Often, the gallbladder is removed during the surgery. However, this may not be reimbursed by insurance carriers. As gallstones result from the excessive metabolism of fats and the subsequent breakdown of cholesterol into crystals, the use of bile salts (ursodiol) prophylatically can reduce the risk of stone formation.31 Patient compliance, however, may not occur due to the frequent dosing.25 In addition, drug interactions may occur when ursodiol is taken with lipid-lowering drugs, antacids containing aluminum, or oral contraceptives. Diagnostic workup includes abdominal ultrasound and occasionally a CT scan either to detect gallstones or to more clearly visualize the abdominal cavity. Surgical referral is necessary.

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Diarrhea

Diarrhea can have several underlying causes. The diagnostic workup should be in concordance with the degree of symptoms. Differential diagnoses include malabsorption, bile salt diarrhea, or dumping syndrome. Surgery may exacerbate irritable bowel syndrome and food intolerances, or cause bacterial overgrowth. The priority is to ensure that the patient is not experiencing metabolic or nutritional complications, then to ascertain the underlying cause. In nonsevere cases, empiric therapy with antibiotics/probiotics for bacterial overgrowth may mitigate benign symptoms.25

Dumping syndrome is a constellation of procholinergic symptoms resulting from ingestion of simple carbohydrates. While most gastric bypass patients experience this within the first 18 months, 5% to 10% of patients will have chronic dumping syndrome.25 Salivation, nausea, vomiting, diarrhea, tachycardia, and dizziness can be severe and frightening. As an adverse reaction of procedures such as RYGB, dumping syndrome is generally self-limited and subsides in 1 to 2 hours after the high carbohydrate load. Educating patients that certain foods produce a painful and uncomfortable reaction can serve as a motivator for dietary adherence.9 Basic dietary teaching includes avoiding sweets, consuming food slowly with carbohydrates mid meal, and avoiding liquids while eating.

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Persistent or recurrent vomiting

Vomiting could be a problem that develops or is aggravated by medications, vitamin supplements, and dehydration. Providers must evaluate intake and stress the importance of small portions and chewing food thoroughly. Persistent or recurrent vomiting may be a chronic problem due to eating habits or a sign of adhesions, obstruction, an anatomical stricture, or an internal hernia.13 Vomiting due to adhesions and obstruction manifests as ingested food without bile. Diagnosis is enhanced with an abdominal CT scan. Surgical referral is required. In patients with either a VBG or LAGB, vomiting can be due to tight banding, gastroesophageal dilatation, or gastric prolapse.14 A UGI or endoscopy, laparoscopy, and possible revision to RYGB may be necessary.25

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Nutritional deficiencies

Vitamin deficiencies resulting from malabsorptive procedures can produce anemia, osteoporosis, peripheral neuropathy, Wernicke-Korsakoff syndrome, and, in the case of pregnant women, neural tube defects in offspring.28 Generally, patients with RYGB or BPD are at high risk of iron, calcium, vitamin D, thiamine, vitamin B12, and folate deficiencies. Restrictive surgical procedures also carry the potential for nutritional deficiencies due to reduced intake of vitamins and minerals. All post-BS patients should take daily vitamin supplements with minerals; this is especially important for those who have undergone malabsorptive procedures.32 Menstruating women are naturally at higher risk of iron deficiency, thus prophylactic iron supplementation is recommended. Gastrointestinal adverse effects may necessitate the ferrous sulfate be taken with food, requiring higher dosing or parenteral administration.

Calcium supplementation with calcium citrate rather than calcium carbonate is recommended because of decreased stomach acid.10 Vitamin D and vitamin B12 supplementation is recommended as well.10,32

Vitamin B1 (thiamine) requires an acid environment for absorption in the small intestine. Patients undergoing malabsorptive procedures are at risk of neurological complications due to deficiencies that occur around 3 months postoperatively.33 Thiamine deficiency can be prevented with daily multivitamins.

Protein-calorie malnutrition can occur either from an anastomotic stricture, protein malabsorbtion, or decreased protein intake or intolerance.9 Treatment depends on the cause and may possibly involve surgical dilatation of a stricture or total parenteral nutrition. In general, patients should be encouraged to eat fish, which is better tolerated than meat.10

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Suboptimal weight loss

As many as 25% to 30% of those who undergo BS obtain inadequate weight loss.26 In the first 3 months, patients generally lose weight quickly, but losses slow during months 3 through 12 and plateau at 1 year. According to investigators, patients often feel the surgery is not working.26 A contrast upper gastrointestinal series may be done to assure that operative integrity is appropriate. Weight regain at 2 to 3 years after surgery is also common. Suboptimal weight loss or weight regain should necessitate evaluation of both dietary adherence and surgical function. Referral for nutrition counseling during these periods can assist patients in developing lifelong dietary strategies.

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Patient management

Optimum care includes at least three postoperative surgical visits within the first year, opportunities for psychological counseling and a support group, and dietary and physical activity counseling in conjunction with a continuing relationship with a primary care provider.19

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Psychosocial follow-up

Most patients experience improvement in psychosocial functioning after BS.34 Quality of life and well-being improvements generally occur within 12 to 18 months. There are, however, reports of suicide and alcohol abuse in patients, as surgery and weight loss may uncover major difficulties in relationships or depressed mood as a result of multiple psychosocial adjustments.32 Careful presurgical psychological evaluation is recommended, as is postoperative support. A supervised support group should be available postoperatively, and patients should be encouraged to participate for at least 6 months.

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Pregnancy

Pregnancy is contraindicated for 18 months after BS due to continuing weight loss and nutritional requirements.9 Contraception counseling is required. Typically, the loss of excess weight after BS improves a woman's fertility. No adverse perinatal outcomes are associated with BS, and effects are generally ranked as positive. Reductions in obesity-related complications, such as gestational diabetes, macrosomia, and preeclampsia, are reported after BS.35 Some evidence indicates that the incidence of cesarean delivery is higher in women who undergo open or laparoscopic surgery, and these patients should be counseled accordingly.35

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Annual lab work

For the first year, the complete blood count (CBC), glucose, and creatinine should be evaluated every 3 months. Every 6 months, liver function tests, protein and albumin, iron, total iron binding capacity (TIBC), ferritin, vitamin B12, folic acid, calcium, and parathyroid hormone should be evaluated.9 Close analysis of the risk of bone loss should be considered using alkaline phosphatase, 24-hour urinary calcium, osteocalcin, and dual-energy X-ray absorptiometry. After the first year, annual testing should continue with CBC, glucose, creatinine, liver function tests, protein and albumin, iron, TIBC, ferritin, vitamin B12, folic acid, calcium, and parathyroid hormone.

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An effective treatment

BS is an effective treatment for morbid obesity and the attendant comorbidities, but it must be accompanied by lifestyles changes for long-term success. Comprehensive and collaborative long-term care is essential for optimum outcomes following bariatric surgery.32

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© 2009 Lippincott Williams & Wilkins, Inc.

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