Indications and Patient Selection for Bariatric Surgery

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Rifat Latifi, Eric J. DeMaria and Harvey J. Sugerman Introduction

Approximately 97 million adults in the United States are overweight or obese; 32.6 % are overweight, defined as a body mass index (BMI) of 25-29.9 kg/m2, while 22.3% are obese with a BMI >30 kg/m2. Morbid obesity, or clinically severe obesity is defined as 100 lb. above ideal body weight, or a BMI >35 kg/m2. Severe obesity (more than 244 lb. for men or more than 225 lb. for women) has been estimated to be present in 4.9% (2.8 million) of men and 7.2% (4.5 million) of women in the United States. As the BMI increases, so does the mortality rate from all causes, especially from cardiovascular disease, which is 50%-100% above that of persons who have BMI in the range 20-25 kg/m2.

Pathophysiology of Morbid Obesity Syndrome

Morbid obesity is a potentially deadly syndrome that is a harbinger of multiple other diseases and disorders, affecting every organ and system of the body, and as such it is associated with several significant clinical conditions.

Cardiovascular Related Problems

Cardiovascular dysfunction in morbidly obese patient is common and is manifested as hypertension, coronary artery disease, and increased complications following coronary artery bypass et cetera. Heart failure may be the consequence of left ventricular hypertrophy and hypertension, left ventricular eccentric hypertrophy, or right ventricular hypertrophy. In addition prolonged Q-T interval and sudden death occur more commonly in morbidly obese patient. Furthermore, patients with hypoventilation syndrome have higher cardiac filling (pulmonary artery and pulmonary capillary wedge) pressures that are higher than pressures in patients with congestive heart failure (CHF), although clinically they are not in CHF. Other problems such as dysrhythmias, ischemic stroke, deep vein thrombosis and pulmonary embolus are common in-patients with morbid obesity.

Respiratory Insufficiency

Respiratory insufficiency of obesity (Pickwickian syndrome) is associated with obesity hypoventilation syndrome and obstructive sleep apnea syndrome (multiple nocturnal awakenings, loud snoring, falling asleep while driving, daytime somnolence). In addition to high filling pressure, most of these patients have abnormal pulmonary function tests.

Metabolic Complications

The relationship of central obesity to the constellation of health problems known as "the metabolic syndrome" or "syndrome X" is well established. It is thought at the present that increased visceral fat increases glucose production that subsequently causes hyperinsulinism and eventually development of type II diabetes mellitus. It has been also established that increased glucose and insulin levels are responsible for polycystic ovary syndrome (Stein-Leventhal syndrome) with ovarian cysts, hirsutism, and amenorrhea as well as non-alcoholic steatohepatitis (NASH) which may progress to liver cirrhosis. Type II diabetes mellitus can cause significant morbidity as it may lead to renal failure, peripheral neuropathy and retinopathy. Other metabolic complications are hypertension, elevated triglycerides, cholesterol and in increased frequency of formation of gallstones.

Increased Intra-Abdominal Pressure

Increased intra-abdominal pressure is well documented in morbidly obese patients and is manifested as stress overflow urinary incontinence, gastroesophageal reflux, nephrotic syndrome, increased intracranial pressure leading to pseudotumor cerebri, hernias, venous stasis, probably hypertension and pre-eclampsia, as well as the nephrotic syndrome. Pseudotumor cerebri is hypothesized to be secondary to an increased intra-abdominal pressure and intra-thoracic pressure with decreased venous drainage from the brain.

Other Co-Morbid Conditions

Hypercoagulapathy, female hormonal dysfunction such as amenorhea, dysmen-orrhea, infertility, hypermenorrhea, increased incidence of breast cancer, uterine, colon, prostate and other cancers and debilitating joint disease involving hips, knees, ankles, feet and lower back are common in these patients. In addition, obese patients clearly experience a multitude of difficulties related to social acceptance in society, work-related problems, body image, reduced mobility, sexual dysfunction and other psychosocial problems that add more pathology to this chronic and deadly disorder. The difficulties in diagnosing and treating surgical conditions in obese patients such as peritonitis, necrotizing panniculitis, necrotizing fasciitis, diverticu-litis, necrotizing pancreatitis and other intra-abdominal infectious catastrophes are significant.

A relationship between obesity and a low-grade systemic inflammatory state has been established and is manifested with elevated proinflammatory cytokines interleukin 6 (IL-6) and C-reactive protein which are thought to contribute to cardiovascular morbidity. Elevated C-reactive protein levels have been associated with increased risk of myocardial infarction, stroke, peripheral arterial disease, and coronary heart disease.

Indications for Surgical Treatment of Morbid Obesity

The causes of severe obesity are multifactorial. However, the chronic imbalance between energy intake and energy expenditure is the most common cause. Genetic and other environmental factors play an important role too.

The published success rate for all medical approaches including diet, pharmaco-therapy and behavioral modification for morbid obesity is dysmal. It has been estimated that over 95% of morbidly obese patients subjected to medical weight-reduction programs regain all of their lost weight, as well as additional excess weight, within two years of the onset of therapy.

Because of the very high failure rate of all non-surgical attempts to correct morbid obesity including diet, behavior modification, hypnosis, voluntary incarceration, jaw wiring and intragastric balloons, the presence of morbid obesity by itself may be an indication for surgical correction. Based on medical evidence, the surgical treatment of patients with BMI >40 kg/m2 or BMI> 35 kg/m2 with co-morbid conditions, has emerged as definitive therapy. Recently, bariatric surgery has gained acceptance among surgeons, physicians and the lay public. The presence of any endocrine disorder that may be responsible for obesity, albeit extremely rare, should be treated first.

Preoperative Patient Evaluation

One of the most important factors in the success of bariatric surgery is appropriate selection of patients. It is clear that surgery is the best method thus far to induce significant weight loss in morbidly obese patients. Yet at the same time the patient should understand that surgery alone is not enough, and that this procedure requires life-long commitment of the patient, their family and their physicians. As recommended by the NIH panel, a patient is a candidate for surgery if he/she has failed nonoperative attempts to lose weight, is motivated and is not addicted to drugs or alcohol. The patient must understand the magnitude of their problem and be able follow the postoperative dietary and other regimens.

Morbidly obese patients requesting bariatric surgery need to be evaluated by their primary medical doctor and bariatric surgical team that consists of a dedicated and experienced surgeon, dietitian, and a nurse. A psychologist and or psychiatrist specializing in behavior modifications should be available for consultation. A very frank conversation(s) between the surgeon and patient and family is most important.

Patients need to understand clearly all phases of the treatment, the procedure itself, and possible complications. While it is a very important step, the surgery itself is probably the easiest phase of what will be lifetime changes for these patients. Only when the patient understands all the intricacies of the procedure, the course of postoperative care and is deemed to be a proper candidate for surgical treatment, should one proceed with surgery. In today's information age when the procedure may be seen on the internet, many patients are much more sophisticated and informed about the operation, the existing expertise, method and techniques of the operation. As part of the preoperative evaluation, the surgeon should perform a careful physical examination and take a complete medical history. Most of the patients have co-morbid diseases and those need to be sought out carefully. In our practice, the surgical team is often the first to suspect the diagnosis of sleep apnea syndrome. Furthermore, the dietary habits, social situation and motivation for the operation should be questioned as well as the history of obesity in the family. Basic laboratory work-up should include a complete blood count, full chemistry panel, iron, B12, thyroid panel, arterial blood gases on room air, EKG, a chest X-ray and urinalysis. If history indicates the suspicion for existence of sleep apnea, the patient should undergo a sleep study. Many morbidly obese patients are seen for the first time after they are involved in trauma situation after falling asleep while driving. These patients should

Table 2.1. Criteria for patient selection for bariatric surgery*

Weight

45 kg or 100% above desirable weight Body mass index>40 kg/m/2

Body mass index >35 kg/m/2 with coexisting morbidities Failure of non-surgical methods of weight reduction Absence of endocrine disorders responsible for morbid obesity Psychological stability Lack of drugs and alcohol abuse

*The 1991 National Institutes of Health Consensus be referred to the bariatric surgeon by the trauma team. The history and physical examination should identify the patients who need further work-up from a cardiovascular standpoint, such as those with hypoventilation syndrome or venous disease. While the choice of bariatric procedure recommended to the patient is based mainly on the local expertise and the tradition, we recommend mostly Roux-en-Y gastric bypass (RYGBP). Whether this procedure is performed laparoscopically or by an open technique, depends on the individual surgeon and patient request. Previous abdominal operations may be a relative contraindication to laparoscopy especially if the surgery was limited to upper abdomen, such as gallbladder surgery. The presence of hypoventilation syndrome is not a contraindication for laparoscopic surgery, especially when the surgeon and the anesthesia team monitor the patient carefully. While some had identified a large left lobe of the liver as a difficult problem, this is not a contraindication to laparoscopic gastric by-pass surgery, although it may be present a significant problem.

Effects of Weight Loss: What Can the Patient Expect?

There are many studies which document the reversibility of most co-morbid obesity conditions. Type II diabetes mellitus will resolve in 85% of patients so that they no longer require insulin or any oral hypoglycemic medication. Obstructive sleep apnea syndrome resolves completely when the respiratory disturbance index is <40 episodes/hour of sleep and improves significantly if >40 at 5 years after surgery. In addition, obesity hypoventilation resolves within 6 to 9 months after surgically induced weight loss with improvement in arterial blood gases, lung volumes and cardiac filling pressures. Cardiac function improves significantly following surgically induced weight loss. Systemic hypertension resolves in two-thirds to three-fourths of the patients who no longer need any anti-hypertensive medications or respond to a much smaller dose. There is a marked improvement in serum lipids following gastric bypass, as well as correction of urinary overflow incontinence in women. Gastroesophageal reflux disease (GERD) is no longer a problem in almost all patients immediately after GBP surgery as there is no acid or bile to reflux from the small gastric pouch; however, this can be a serious complication of vertical banded gastroplasty (VBG) necessitating conversion to GBP. Venous stasis ulcers will heal and lower extremity peripheral edema resolve following surgically induced weight loss, presumably as a result of decreased abdominal pressure on the inferior vena cava. Pregnancy may be a complication of bariatric surgery as women begin to ovulate and become fertile; unfortunately, their hirsutism will not go away with weight loss. It is recommended that women take contraceptive precautions for 1 year after bariatric surgery because of the potential risk of neural tube defects (spina bifida, etc.) with nutritional impairment during pregnancy. Pseudotumor cerebri has also been shown to resolve after surgically induced weight loss; these patients no longer suffer from constant headaches and pulsatile tinnitus and their opening cerebrospinal fluid (CSF) pressures normalize. Patients with degenerative joint disease involving the hips, knees, ankles and lower back will usually claim a marked decrease in pain and improved mobility following marked weight loss, but there are no studies documenting this impression to date. It may obviate the need, either temporarily or longer, for artificial joint replacement. There are no data to date evaluating the effect of major weight loss on non-alcoholic steatohepatitis (NASH), although the standard recommendation for these patients is to lose weight. Psychological evaluation has found a significant improvement in self-image and symptoms of depression, but one study has noted that the severity of depression may return to pre-surgical levels at 5 years after surgery in the absence of weight regain and may be associated with the risk of suicide.

The Reason(s) for Inadequate Weight Loss or Weight Regain Following Gastric Bypass Surgery

The average patient loses two-thirds of their excess weight, or about one-third of their preoperative weight, following a gastric bypass procedure. At five years after surgery, the average loss of excess weight is 60% and it is 50% at ten years. Better long-term weight loss may be seen following the partial biliopancreatic bypass or duodenal switch malabsorptive procedures although at the potential cost of malnutrition. Approximately 15% of patients will fail to lose more than 40% of their excess weight following a gastric bypass procedure. This percentage is much higher following banded gastroplasty procedures and, presumably, following laparoscopic gastric banding. In patients who have undergone either a stapled gastroplasty or gastric bypass, there is always a possibility of staple line disruption, especially if the patient states they are able to eat much larger quantities of food at a time. An UGI should determine if this complication has occurred and, should that be found, operative revision can be undertaken. Revisional procedures in bariatric surgery are associated with a higher frequency of complications, including anastomotic leak. The primary cause of failed weight loss following gastric bypass is the frequent ingestion of high fat junk (potato or corn chips) and fried foods (French fried potatoes) or the ability to tolerate high-density carbohydrates such as non-dietetic sodas, lemonade, cookies and ice cream. Dilation of the gastrojejunal stoma does occur but surgical revision does not lead to weight loss. Conversion to a malabsorptive distal gastric bypass is effective for improved weight loss but risks the development of protein-calorie malnutrition and steatorrhea with foul-smelling stools and fat-soluble vitamin deficiencies. It is thought that only patients with severe obesity co-morbidity (severe hypertension resistant to drug therapy, obesity hypoventilation or diabetes) who have failed a standard gastric bypass should be offered conversion to a malabsorptive procedure and then only after thoroughly informed consent as to its risks.

Selected Readings

1. NIH Conference: Methods for voluntary weight loss and control. NIH Technology Assessment Conference Panel. Consensus Development Conference, 30 March to 1 April 1992. Ann Intern Med 1993; 119:764-70.

2. NIH Conference: Gastrointestinal surgery for severe obesity: Consensus Development Conference Panel. Ann Intern Med 1991; 115:956-61.

3. Johnson D, Drenick EJ. Therapeutic fasting in morbid obesity. Arch Intern Med 1977; 137:1381-2.

4. Sugerman HJ, Kellum JM JR, DeMaria EJ, Reines HD. Conversion of failed or complicated vertical banded gastroplasty to gastric bypass in morbid obesity. Am J Surg 1996; 171:263-9.

5. Sugerman HJ, Starkey JV, Birkenhauer RA. A randomized prospective trial of gastric bypass versus vertical banded gastroplasty and their effects on sweets versus non-sweet eaters. Ann Surg 1987; 205:613-24.

6. Hall JC, Watts JM, O'Brien PE, et al. Gastric surgery for morbid obesity. The Adelaide study. Ann Surg 1990; 211:419-27.

7. Schauer PR, Ikramuddin S, Ramanathan R, Gourash W, Panzak G. Outcomes after laparoscopic Roux-en-Y gastric bypass for morbid obesity. Ann Surg 2000; 232:515-29.

8. Pories WJ, Swanson MS, Macdonald KG. Long SV, et al. Who would have thought it? An operation proves to be the most effective therapy for adult-onset diabetes mellitus. Ann Surg 1995; 222:339-50.

9. Sugerman HJ, Fairman RP, Sood RK, Engle K, Wolfe L, Kellum JM. Long-term effects of gastric surgery for treating respiratory insufficiency of obesity. Am J Clin Nutr 1992; 55:597S-601S.

10. Sugerman HJ, Windsor ACJ, Bessos MK, Wolfe L. Abdominal pressure, sagittal abdominal diameter and obesity co-morbidity. J Int Med 1997; 241: 71-9.

11. Sugerman HJ, Baron PL, Fairman RP, Evans CR, Vetrovek GW. Hemodynamic dysfunction in obesity hypoventilation syndrome and the effects of treatment with surgically induced weight loss. Ann Surg 1988; 207:604-13.

12. Sugerman HJ, Brewer WH, Shiffman ML, et al. A multi-center, placebo-controlled, randomized, double blind, prospective trial of prophylactic ursodiol for the prevention of gallstone formation following gastric-bypass-induced rapid weight loss. Am J Surg 1995; 169:91-7.

13. Sugerman HJ, Kellum JM, Reines HD, et al. Greater risk of incisional hernia with morbidly obese than steroid dependent patients and low recurrence with pre-fascial polypropylene mesh. Am J Surg 1996; 17:80-4.

14. Sugerman HJ, Felton WL, Sismanis A, Salvant JB, Kellum JM. Effects of surgically induced weight loss on pseudotumor cerebri in morbid obesity. Neurology

15. Sugerman HJ, Felton WL III, Sismanis A, Kellum JM, DeMaria EJ, Sugerman EL. Gastric Surgery for pseudotumor cerebri associated with severe obesity. Ann Surg 1999; 229:634-42.

16. Sugerman HJ, DeMaria EJ, Felton WL III, et al. Increased intra-abdominal pressure and cardiac filling pressures in obesity-associated pseudotumor cerebri. Neurology 1997; 49:507-511.

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