Posted by Dr. Kartik Shah on Saturday, 16th May 2009Anatomy and Physiology
Obesity is an excess of body fat. Many factors influence body fat, including lifestyle habits and genetics. There are many ways to treat obesity. Bariatric surgery treats obesity by altering the digestion and absorption of food.
In normal digestion, food moves through the mouth, down the esophagus, and into the stomach. Here, food is mixed with digestive juices. The partially digested material is slowly released into the small intestine.
In the small intestine, digestion is completed. Nutrients and calories are absorbed into the blood stream. There are three parts to the small intestine—duodenum, jejunum, and ileum. Wastes are eventually passed to the colon and released as stool.
There are two types of bariatric surgery. “Restrictive” procedures decrease the size of the stomach so a person feels full quickly. After surgery, the stomach holds about one cup of food; a normal stomach holds 4–6 cups. “Malabsorptive” procedures decrease the absorption of calories in the small intestine. The most common procedure, the Roux–en–Y gastric bypass, is both restrictive and malabsorptive.
Reasons for Procedure
Obesity is a serious health concern. It increases the risk of numerous diseases, some of which include: diabetes, cardiovascular disease, including coronary heart disease, high blood pressure, and stroke, certain types of cancer, gallstones, osteoarthritis, gout, and breathing problems such as sleep apnea.
Obesity is often diagnosed by using the body mass index, or BMI. This is a measure of body fat based on the relationship between a person’s height and weight: 18.5–24.9 is normal weight, 25–29.9 is overweight, 30–39.9 is obesity, 40 or greater is morbid obesity.
Morbid obesity is also defined as 100 pounds over what is considered a healthy weight for a person’s height.
People who carry fat in their abdomen, as opposed to on their hips, are at greater risk for some of the health problems associated with obesity. Therefore, waist circumference is also used to assess weight. A waist circumference greater than 35 inches for women or 40 inches for men is considered high risk.
Weight loss efforts should begin with lifestyle changes, such as eating a low calorie, well–balanced diet and exercising regularly. If obesity persists despite an aggressive diet and exercise program, your doctor may advise adding weight loss medications.
If lifestyle changes and medications are unsuccessful or not possible, bariatric surgery may be considered in the following cases: BMI greater than 40, BMI 35–39.9, and a life–threatening condition, such as heart disease or diabetes, severe physical limitations that affect employment, mobility, and family life.
All candidates for bariatric surgery must commit to major lifestyle changes indefinitely after the procedure.
In the days leading up to your procedure: arrange for a ride to and from the hospital, and for help at home as you recover; the night before, eat a light meal and do not eat or drink anything after midnight; if you regularly take medications, herbs, or dietary supplements, your doctor may recommend temporarily discontinuing them; do not start taking any new medications, herbs, or dietary supplements without consulting your doctor; you may be given antibiotics to take before coming to the hospital; you may be given laxatives and/or an enema to clear your intestines.
Before the procedure, an intravenous line will be started. Bariatric surgery requires general anesthesia, which puts you to sleep for the duration of the procedure. A breathing tube will be inserted through your mouth and into your windpipe to help you breathe during the operation.
Gastric bypass, technically referred to as Roux–en–Y gastric bypass, is both a restrictive and malabsorptive procedure. There are two surgical methods used for gastric bypass. The open method requires an 8–10 inch incision in the abdomen. The laparoscopic method only requires several small “keyhole” incisions through which your surgeon will pass a laparoscope and surgical tools. A laparoscope is a thin, lighted instrument that projects images of the surgery on a monitor in the operating room.
In the Roux–en–Y gastric bypass procedure, your surgeon will use surgical staples to create a small compartment, which will serve as your new stomach. This pouch will hold about one cup of food. The lower portion of the stomach continues to secrete digestive juices, but does not receive food.
Next, your surgeon will cut the small intestine well beyond the stomach and bring one free end up and attach it to the pouch. He or she will then attach the other free end lower down on the small intestine, creating a Y–shape. By bypassing the lower stomach and the first part of the small intestine, fewer calories will be absorbed as food passes though this new pathway.
Banding techniques are restrictive procedures. They help decrease food intake in two ways: by shrinking the stomach to a small pouch and making a tiny opening from the pouch to the rest of the stomach. Food moves slowly through this opening. These factors make you feel full quicker and for a longer time.
In vertical banded gastroplasty, your surgeon will place staples across your stomach to create a small pouch on top. Food will move from this pouch through a tiny opening into the lower stomach and the rest of the digestive tract. To prevent stretching, your surgeon will wrap a rigid, plastic band around the opening.
For adjustable gastric banding, your surgeon will wrap an inflatable band around the top of the stomach. As the band is inflated, it will squeeze the stomach to create a small pouch and a narrow opening into the larger, lower portion. This may be done though tiny incisions using a laparoscope. The band may be adjusted at any time.
In biliopancreatic diversion, which is a malabsorptive procedure, your surgeon will begin by removing part of the stomach, leaving only a small pouch behind. Next, he or she will sew the small intestine to the pouch. This creates a direct route from the pouch to the end of the small intestine. The duodenum and jejunum are bypassed, so few calories and nutrients are absorbed.
For all methods of bariatric surgery, your surgeon will close your incisions with staples or stitches. You will then be brought to the recovery room.
Risks and Benefits
Obesity itself is a risk factor for complications in any surgery. Risks associated with bariatric surgery include: nutritional deficiencies, abdominal hernia, gallstones, infection, heart and lung problems, blood clots in the legs, which can travel to the lungs, complication of the general anesthesia, and/or death.
Additional risks associated with restrictive procedures include: vomiting from eating too much or not chewing enough, band slippage, breakdown of the staple line leading to leakage of stomach juices into the abdomen, ulcers that may bleed.
Patients who have a malabsorptive procedure may also experience dumping syndrome, which occurs when stomach contents move too quickly through the small intestine. Symptoms, which occur after eating, include: nausea, weakness, sweating, faintness, and diarrhea.
If post–surgical lifestyle changes are made and maintained, the benefits of bariatric surgery include: long–term, consistent weight reduction, for some people, 100 pounds or more may be lost, improvement in many obesity–related conditions, such as decreased blood sugar and blood pressure, and enhanced self–esteem.
In gastric bypass surgery, or any procedure, you and your doctor must carefully weigh the risks and benefits to determine whether it’s the most appropriate treatment choice for you.
After the Procedure
After your procedure, the breathing tube will be removed and you will be taken to the recovery area for monitoring. You will be given pain medication and your diet will be gradually advanced over several days. If you had a laparoscopic procedure, you can expect to be discharged home in 2–5 days. After an open procedure, your hospital stay may be longer.
Once you are home, be sure to contact your doctor if you experience: signs of infection such as fever and chills, redness, swelling, increasing pain, bleeding, or discharge at the site of your incisions, cough, shortness of breath, or chest pain, worsening abdominal pain, blood in the urine or stool, pain, burning, urgency, or frequency of urination, persistent nausea and/or vomiting, pain or swelling in your feet, calves, or legs, any other worrisome symptoms.
You may be out of work for 4–5 weeks. For best results after bariatric surgery, you’ll need to practice lifelong healthful habits. These include exercise and specific nutrition guidelines. It will be essential to meet regularly with your healthcare team to help you stay on track.