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Gastric bypass surgery

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Gastric Bypass (GBP) refers to a group of similar operative procedures used to treat morbid obesity, a condition which arises from severe accumulation of excess weight as fatty tissue, and the resultant health problems ("co-morbidities") which occur. Bariatric surgery is the surgical treatment of morbid obesity, and includes the gastric bypass procedures as one of several classes of operations.

A gastric bypass consists of a division of the stomach into a small upper pouch and a much larger, lower "remnant" pouch, accompanied by re-arrangement of the small intestines to permit both pouches to remain connected. The manner in which the intestines are reconnected gives rise to several variations of the procedure. The operation leads to a marked reduction in the functional volume of the stomach, accompanied by an altered physiological and psychological response to food. Weight loss is typically dramatic, and co-morbidities are markedly reduced.

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Co-Morbid Conditions

Obesity becomes life-threatening when it causes health problems, which are a consequence of its mechanical or metabolic effects. These co-morbidities may in turn lead to severe deterioration of health, shortened life expectancy, and impaired enjoyment of lifestyle.

Major co-morbidities include:

Atherosclerotic Cardiovascular Disease (ASCVD). Obesity is associated with the occurrence of hypercholesterolemia, hypertriglyceridemia, and is a factor in the occurrence of atherosclerosis, the deposition of fats within the walls of the blood vessels. This leads to conditions such as coronary artery disease, congestive heart failure, and "hardening of the arteries". This group of conditions is a leading cause of death in the United States.

Diabetes Mellitus Type 2 Also called adult-onset diabetes, this form of diabetes occurs mostly in middle and older ages, and is up to 40 times as likely in those who are severely overweight. It is associated with ASCVD, kidney failure, blindness, nerve damage, and amputations of the extremities, and is also a leading overall cause of death in the United States. Dysmetabolic Syndrome X, a pre-diabetic condition frequently associated with obesity, is accompanied by elevated levels of insulin in the blood, and a high incidence of early development of coronary heart disease.

Essential Hypertension or "high blood pressure", is much more common in obese individuals. It can lead to early development of ASCVD, as well as to kidney disease. Weight loss is considered to be an important feature of treatment.

Obstructive Sleep Apnea (OSA) Persons with this condition tend to suffer from airway obstruction when asleep, as the muscles relax and the weight and bulk of tissues collapses the throat passages. An observer notices loud snoring, frequent periods when breathing ceases (apneas), and episodes of restlessness and partial awakening. The afflicted patient is often unaware of the nature of the problem, but may notice frequent awakening at night, dry mouth, a sense of having slept poorly, daytime drowsiness and fatigue, or inappropriate sleeping (such as at work, in meetings, or while driving). This condition has a significant associated mortality.

Gastroesophageal Reflux Disease (GERD) is characterized by regurgitation (reflux) of acid and gastric contents into the esophagus, and sometimes into the back of the throat. Gastric acid and bile are very corrosive to the lining membrane of the esophagus, and cause it to become inflamed (esophagitis) and sometimes scarred (esophageal stricture). Reflux which occurs while sleeping can lead to sudden coughing and choking at night, a burning sensation in the throat (pyrosis), and inhalation of acid and stomach contents into the lungs, with the risk of hoarseness, bronchitis, pneumonia, lung abscess and lung scarring. GERD is often associated with development of asthma, and causation of asthmatic attacks, and may also be aggravated by OSA.

Gall-Bladder Disease is much more likely in obese individuals, being associated with formation of gallstones, usually composed of crystallized cholesterol, within the gallbladder. Although readily treatable by removal of the gallbladder (cholecystectomy), it may lead to life-threatening problems such as obstruction of the ducts from the liver, jaundice, and inflammation of the pancreas (gallstone pancreatitis).

Liver Disease is present in some degree in 90% of persons who undergo bariatric surgery, usually a manifestation of the metabolic effects of obesity on the liver. This may take the form of large fat globules within the liver cells (steatosis), chronic inflammation of the liver (steatohepatitis), and in a few instances, cirrhosis of the liver. The latter condition may lead to liver failure and the need for a liver transplant.

Venous Thromboembolic Disease (VTE) affects the legs, and causes swelling, thickening and discoloration of the skin, and ulceration of the skin. This condition begins with damage to the veins of the legs, associated with formation of blood clots (thrombophlebitis), often associated with an injury, a pregnancy (even use of birth-control pills or hormones), or a surgical operation. When a newly formed blood clot breaks loose, and floats through the veins to the heart and lungs, it is called a pulmonary embolus. This may sometimes be fatal within minutes. More commonly, the blood clot remains in place locally, and heals by becoming a scar, which permanently damages the vein. Once damaged, the veins cannot fully function to return blood to the heart, and increased venous pressure in the legs causes swelling, impaired circulation in the skin, and sometimes skin breakdown. Obesity is a major risk factor in development of VTE, and may also aggravate the increased venous pressure in the legs.

Degenerative Disc Disease is a progressive "wearing-out" of the cartilage disks between the vertebral bones of the spine. It occurs more often and earlier in life in obese persons, due to the markedly increased mechanical stress on the disks from the extra weight. Its most common sign is chronic low back pain, which may be disabling. This condition is also associated with sciatica, lumbar spondylosis, and spinal stenosis.

Degenerative Disease of the Weight-Bearing Joints, or osteoarthritis, affecting the hips, knees, ankles and feet, occurs earlier in life, and in greater degree, in obese individuals, due to the mechanical stresses of excess weight. Joint pain, loss of mobility, and joint replacement surgery are much more likely in obese persons.

Surgical Indications

Gastric Bypass is indicated for the surgical treatment of morbid obesity, a diagnosis which is made when the patient is seriously obese, has been unable to achieve satisfactory and sustained weight loss by dietary efforts, and is suffering from co-morbid conditions which are either life-threatening or a serious impairment to the quality of life.

In the past, serious obesity was interpreted to mean weighing at least 100 pounds more than the "ideal body weight", an actuarially determined body weight at which one was estimated to be likely to live the longest, as determined by the life insurance industry. This criterion failed for persons of short stature.

In 1991, a Consensus Panel of physicians was sponsored by the National Institutes of Health, and its recommendations have set the current standard for consideration of surgical treatment, the Body Mass Index (BMI). The BMI is defined as the body weight (in kilograms), divided by the square of the height (in meters). The result is expressed as a number usually between 20 and 70, in units of kilograms per square meter.

The Consensus Panel of the National Institutes of Health (NIH) recommended the following criteria for consideration of bariatric surgery, including gastric bypass procedures:

  1. People who have a body mass index (BMI) of 40 or higher. Or,
  2. People with a BMI of 35 or higher with one or more related comorbid conditions.
The Consensus Panel also emphasized the necessity of multidisciplinary care of the bariatric surgical patient, by a team of physicians and therapists, to manage associated co-morbidities, nutrition, physical activity, behavior and psychological needs. The surgical procedure is best regarded as a tool which enables the patient to alter lifestyle and eating habits, and to achieve effective and permanent management of their obesity and eating behavior.

Since 1991, major developments in the field of bariatric surgery, particularly laparoscopy, have outdated some of the conclusions of the NIH panel. In 2004, a Consensus Conference was sponsored by the American Society for Bariatric Surgery (ASBS), which updated the evidence and the conclusions of the NIH panel. This Conference, composed of physicians and scientists of many disciplines, both surgical and non-surgical, reached several conclusions, amongst which were:

Surgical Techniques

The gastric bypass, in its various forms, accounts for a large majority of the bariatric surgical procedures performed. It is estimated that 140,000 such operations were performed in the United States in 2005. An increasing number of these operations are now performed by limited access techniques, termed "laparoscopy".

Laparoscopic surgery is performed using several small incisions, or ports, one of which conveys a surgical telescope connected to a video camera, and others permit access of specialized operating instruments. The surgeon actually views his operation on a video screen. The method is also called limited access surgery, reflecting both the limitation on handling and feeling tissues, and also the limited resolution and two-dimensionality of the video image. With experience, a skilled laparoscopic surgeon can perform most procedures as expeditiously as with an open incision — with the option of using an incision should the need arise.

The Laparoscopic Gastric Bypass, Roux-en-Y, first performed in 1993, is regarded as one of the most difficult procedures to perform by limited access techniques, but use of this method has greatly popularized the operation, with benefits which include shortened hospital stay, reduced discomfort, shorter recovery time, less scarring, and minimal risk of incisional hernia.

Essential Features

The gastric bypass procedure consists in essence of:

—Creation of a small,(15-30 ml/1-2 tbsp) thumb-sized pouch from the upper stomach, accompanied by bypass of the remaining stomach (about 400 ml and variable). This restricts the volume of food which can be eaten. The stomach may simply be partitioned (typically by the use of surgical staples), or it may be totally divided into two parts (also with staplers). Total division is usually advocated, to reduce the possibility that the two parts of the stomach will heal back together ("fistulize"), negating the operation.

—Re-construction of the GI tract to enable drainage of both segments of the stomach. The technique of this reconstruction produces several variants of the operation, which differ in the lengths of small bowel used, the degree to which food absorption is affected, and the likelihood of adverse nutritional effects.

Variations of the Gastric Bypass

Loop Gastric Bypass

The first use of the gastric bypass, in 1967, used a loop of small bowel for re-construction. Although simpler to create, this approach allowed corrosive juices from the small bowel to enter the gastric pouch, sometimes causing severe inflammation and ulceration of either the stomach or the lower esophagus. It was soon abandoned by its originators, in favor of less troublesome techniques, but has recently been employed again by a few surgeons, as the "Mini-Gastric-Bypass", mainly to simplify the challenge of reconstruction, when performed laparoscopically. Although mini-gastric bypass has been asserted to have a low complication rate, there are now multiple reports in the medical literature of serious long-term complications with the technique, necessitating major revisional surgery.

Gastric Bypass, Roux en-Y (Proximal)

This variant is the most commonly employed gastric bypass technique, and is by far the most commonly performed bariatric procedure in the United States. It is the operation which is least likely to result in nutritional difficulties. The small bowel is divided about 18 inches below the lower stomach outlet, and is re-arranged into a Y-configuration, to enable outflow of food from the small upper stomach pouch, via a "Roux limb". In the proximal version, the Y-intersection is formed near the upper (proximal) end of the small bowel. The Roux limb is constructed with a length of 80 to 150 cm (30 to 60 inches), preserving most of the small bowel for absorption of nutrients. The patient experiences very rapid onset of a sense of stomach-fullness, followed by a feeling of growing satiety, or "indifference" to food, shortly after the start of a meal.

Gastric Bypass, Roux en-Y (Distal)

The normal small bowel is 600 to 1000 cm (20 to 33 feet) in length. As the Y-connection is moved farther down the Gastrointestinal tract, the amount of bowel capable of fully absorbing nutrients is progressively reduced, in pursuit of greater effectiveness of the operation. The Y-connection is formed much closer to the lower (distal) end of the small bowel, usually 100 to 150 cm (40 to 60 inches) from the lower end of the bowel, causing reduced absorption (mal-absorption) of food, primarily of fats and starches, but also of various minerals, and the fat-soluble vitamins. The unabsorbed fats and starches pass into the large intestine, where bacterial action may act on them to produce irritants and malodorous gases. These increasing nutritional effects are traded for a relatively modest increase in total weight loss.

Physiology of the Gastric Bypass

The gastric bypass reduces the size of the stomach by well over 90%. A normal stomach can stretch, sometimes to over 1000 ml, while the pouch of the gastric bypass may be 15 ml in size. The Gastric Bypass pouch is usually formed from the part of the stomach which is least susceptible to stretching. That, and its small original size, prevents any significant long-term change in pouch volume. What does change, over time, is the size of the connection between stomach and bowel, and the ability of the small bowel to hold a greater volume of food. Over time, the functional capacity of the pouch increases; by that time, weight loss has occurred, and the increased capacity serves to allow maintenance of a lower body weight.

When the patient ingests just a small amount of food, the first response is stretching of the wall of the stomach pouch stimulates nerves which tell the brain that the stomach is full. The patient feels a sensation of fullness, as if he/she had just eaten a large meal -- but with just a thumbful of food. Most persons do not stop eating, simply in response to a feeling of fullness, but one rapidly learns that subsequent bites must be eaten very slowly and carefully, to avoid increasing discomfort, or even vomiting.

Normally when we eat, food passes out of the stomach into the duodenum, after about 30 minutes. When it reaches the lower end of the duodenum, a new hormonal message is generated, telling the brain that enough food has been eaten. The person with a normal GI tract experiences this hormone release as a sense of satisfaction or "satiety" — a feeling of indifference toward eating any more. Recently, a hormone called ghrelin has been discovered, which may have something to do with this effect.

The gastric bypass, when the bowel is re-arranged, moves this portion of the bowel to connect it with the small gastric pouch. The Gastric Bypass patient, within just a few minutes, and before she can eat more than a small amount, begins to get a feeling like "who cares", and comfortably decides not to eat any more.

To gain the maximum benefit from this physiology, it is important that the patient eat only at mealtime, 2 to 3 meals daily, and avoid snacks and grazing between meals, which can effectivly "bypass the bypass". This requires a change in eating behavior, and alteration of long-acquired habits for finding food. The Gastric Bypass is a powerful tool for enabling change in eating behavior to a healthy form.

In almost every case where weight gain occurs late after surgery, capacity for a meal has not greatly increased. The real cause of regaining weight is eating between meals, usually high-caloric snack foods. There is no known operation which can completely counteract the adverse effects of destructive eating behavior.

Complications

Any major surgery involves the potential for complications — adverse events which increase risk, hospital stay, and mortality. Some complications are common to all abdominal operations, while some are specific to bariatric surgery. A person who chooses to undergo surgery should know about these risks and has implicitly accepted them.

Mortality

Mortality occurs in about 0.5% of patients, after GBP. Mortality is affected by complications, which in turn are affected by pre-existing risk factors such as degree of obesity, heart disease, obstructive sleep apnea, diabetes mellitus, and history of prior pulmonary embolism. It is also affected by the experience of the operating surgeon: the "learning curve" for laparoscopic bariatric surgery is estimated to be about 100 cases, and inexperienced surgeons have been shown,in several studies, to have a significantly higher rate of complications and mortality. Unfortunately, the way a surgeon becomes experienced in dealing with problems is mostly to have problems to deal with.

Complications of Abdominal Surgery

Infection

Infection of the incisions, or of the inside of the abdomen (peritonitis, abscess) may occur, due to release of bacteria from the bowel during the operation. Nosocomial infection, such as pneumonia, bladder or kidney infections, and sepsis (bloodborne infection) are also possible. Effective short-term use of antibiotics, diligent respiratory therapy, and encouragement of activity within a few hours after surgery, can reduce the risks of infections.

Hemorrhage

Many blood vessels must be cut, to divide the stomach and to move the bowel. Any of these may later begin bleeding, either into the abdomen (inra-abdominal hemorrhage), or into the bowel itself (gastrointestinal hemorrhage). Transfusions may be needed, and re-operation is sometimes necessary. Use of blood thinners, to prevent venous thromboembolic disease, may actually increase the risk of hemorrhage slightly.

A hernia is an abnormal opening, either within the abdomen, or through the abdominal wall muscles. An internal hernia may result from surgery, and re-arrangement of the bowel, and is mainly significant as a cause of bowel obstruction. An incisional hernia occurs when a surgical incision does not heal well; the muscles of the abdomen separate and allow protrusion of a sac-like membrane, which may contain bowel or other abdominal contents, and which can be painful and unsightly. The risk of abdominal wall hernia is markedly decreased in laparoscopic surgery.

Abdominal surgery always results in some scarring of the bowel, called adhesions. A hernia, either internal or through the abdominal wall, may also result. When bowel becomes trapped by adhesions or a hernia, it may become kinked and obstructed, sometimes many years after the original procedure. Usually an operation is necessary, to correct this problem.

Venous Thromboembolism

Any injury, such as a surgical operation, causes the body to increase the coagulation of the blood. Simultaneously, activity may be reduced. There is an increased probability of formation of clots in the veins of the legs, or sometimes the pelvis, particularly in the morbidly obese patient. A clot which breaks free and floats to the lungs is called a pulmonary embolus, a very dangerous occurrence. Commonly, blood thinners are administered before surgery, to reduce the probability of this type of complication.

Complications of Gastric Bypass

Anastamotic Leakage

An anastamosis is a surgical connection, between the stomach and bowel, or between two parts of the bowel. The surgeon attempts to create a water-tight connection, by connecting the two organs with either staples or sutures, either of which actually makes a hole in the bowel wall. He relies on the healing power of the body, and its ability to create a seal like a self-sealing tire, to succeed with the surgery. If that seal fails to form, for any reason, fluid from within the gastrointestinal tract can leak into the sterile abdominal cavity, and give rise to infection and abscess formation. Leakage of an anastamosis can occur in about 2% of gastric bypass procedures, usually at the stomach-bowel connection. Sometimes leakage can be treated with antibiotics, and sometimes it will require immediate re-operation. It is usually safer to re-operate, if an infection cannot be definitely controlled immediately.

Anastamotic Stricture

As the anastamosis heals, it forms scar tissue, which naturally tends to shrink ("contract") over time, making the opening smaller. This is called a "stricture". Usually, the passage of food through an anastamosis will keep it stretched open, but if the inflammation and healing process outpaces the stretching process, scarring may make the opening so small that even liquids can no longer pass through it. The solution is a procedure called gastroendoscopy, and stretching of the connection by inflating a balloon inside it. Sometimes this manipulation may have to be performed more than once, to achieve lasting correction.

Normally, the pyloric valve at the lower end of the stomach regulates the release of food into the bowel. When the Gastric Bypass patient eats a sugary food, the sugar passes rapidly into the bowel, where it gives rise to a physiological reaction called Dumping Syndrome. An affected person feels his heart beating rapidly and forcefully, breaks into a cold sweat, gets a feeling of butterflies in the stomach, and has a "sky is falling" type of anxiety. He usually has to lie down, and is very uncomfortable for about 30 to 45 minutes. Diarrhea may then follow. The dumping syndrome is a response to a behavior which the patient should not be doing anyway: eating sugary foods. It is not life-threatening, and may assist one in making healthier food choices.

Nutritional Deficiencies

After surgery your eating habits will change drastically due to the stomach size. It is very important to follow your surgeons instructions on food consumption. Most patients with a GBP excellent nutrition can be accomplished and maintained by the consumption of 4-6 small meals daily with adequate protein intake, and the use of complete vitamin and mineral supplements. A guideline to Gastric bypass diet will help guide you from surgery to recovery to living a fuller healthy life through better nutrition.

Proteins are essential food substances, contained in foods such as meat, fish and poultry, dairy products, soy, and eggs. With reduced ability to eat a large volume of food, gastric bypass patients must focus on eating their protein requirements first, and with each meal. Proximal GBP rarely leads to protein deficiency, if this simple precaution is followed. Distal GBP is more likely to lead to protein deficiency, particularly if fat intake is excessive, and the position of the Y-connection is far downstream.

The profound weight loss which occurs after bariatric surgery is due to taking in much less energy (calories) than the body needs to use every day. Fat tissue must be burned, to offset the deficit, and weight loss results. Eventually, as the body becomes smaller, its energy requirements are decreased, while the patient simultaneously finds it possible to eat somewhat more food. When the energy consumed is equal to the calories eaten, weight loss will stop. Proximal GBP typically results in loss of 60 to 80% of excess body weight, and very rarely leads to excessive weight loss. The risk of excessive weight loss is slightly greater with Distal GBP.

Vitamins are normally contained in the foods we eat, as well as any supplements we may choose to take. The amount of food which will be eaten after GBP is severely reduced. Supplements should therefore be taken, to completely cover minimum daily requirements of all vitamins and minerals. Absorption of most vitamins is not seriously affected, after Proximal GBP, although Vitamin B-12 may not be well-absorbed in some persons. Sub-lingual preparations of B-12 will provide adequate absorption. After the Distal GBP, fat-soluble vitamins A, D and E may not be well-absorbed, particularly if fat intake is large. Water-dispersed forms of these vitamins may be indicated, on specific physician recommendation.

All versions of the GBP bypass the duodenum, which is the primary site of absorption of both Iron and Calcium. Iron replacement is essential in menstruating females, and supplementation of iron and calcium is preferable in all patients. Ferrous sulfate is poorly tolerated. Alternative forms of iron (fumarate, gluconate, chelates) are less irritating and probably better absorbed. Calcium carbonate preparations should also be avoided; calcium as citrate or gluconate, 1200 mgm as calcium, has greater bio-availability independent of acid in the stomach, and will likely be better absorbed.

Complication Rate

In experienced hands, the overall complication rate of this type of surgery is approximately 10%. Many complications do not prolong hospitalization significantly. These rates are comparable to those for most major abdominal operations.

Results and Health Benefits of Gastric Bypass

Weight loss of 65 to 80% of excess body weight (the amount by which actual body weight exceeds actuarial ideal body weight) is typical of most large series of Gastric Bypass operations reported. The medically more significant effects are a dramatic reduction in co-morbid conditions: — Hypercholesterolemia is corrected in over 70% of patients. — Essential Hypertension is relieved in over 70% of patients, and medication requirements are usually reduced in the remainder. — Obstructive Sleep Apnea is markedly improved with weight loss, so that most patients are asymptomatic, and often do not even snore, within one year. — Diabetes Mellitus, Type 2, is reversed in up to 90% of patients, usually leading to a normal blood sugar without medication, sometimes within days of surgery. — Gastroesophageal Reflux Disease is relieved from the time of surgery in almost all patients. — Venous thromboembolic disease signs such as leg swelling are typically much improved. — Low back pain and joint pain are typically relieved or improved in nearly all patients.

A recent study (2005) in a large comparative series of patients showed a 89% reduction in mortality over the 5 years following surgery, compared to a non-surgically treated group of patients. There were accompanying decreases in the incidence of cardiovascular disease, infections, and cancer.

Concurrently, most patients are able to alter their lifestyle, to consume "healthier" foods, exercise more regularly, and to enjoy greater participation in family and social activities. Bariatric surgery is the most effective treatment for morbid obesity, and can markedly improve health and lifestyle.

Centers of Excellence

Persons who are considering bariatric surgery should find an experienced and well-qualified surgeon at a well-equipped hospital, which has a network of collaborating healthcare professionals to assist him in the complete care of the patient's medical, nutritional, and psychological needs. There are two national certification programs which evaluate bariatric surgery centers for:

SRC Centers of Excellence

The American Society for Bariatric Surgery established the independent Surgical Review Corporation to certify Centers of Excellence [link] Over 100 qualified bariatric programs, with over 250 surgeons, have been qualified nationwide.

ACS Bariatric Surgery Center Network

The American College of Surgeons Bariatric Surgery Center Network [link] is a listing of centers approved by that organization.

International Federation for the Surgery of Obesity

This multinational organization unites bariatric surgeons of many countries. Many leading surgeons are also members of ASBS. Persons seeking a qualified surgeon may check the ASBS website [link], or a listing of IFSO Councils by country [link].

Gastric bypass among celebrities

The often-cited risks of the surgery, and its dramatic results has brought a large amount of public scrutiny and interest in the procedure. A number of high profile individuals have also brought publicity to the procedure. Some of the more notable patients of the surgery include:

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