The
American Society for Bariatric Surgery describes two basic approaches
that weight loss surgery takes to achieve change:
Restrictive procedures that decrease food intake.
Malabsorptive procedures that alter digestion, thus causing the food
to be poorly digested and incompletely absorbed so that it is eliminated
in the stool.
Gastric Restrictive Procedure - Vertical Banded Gastroplasty
Vertical Banded Gastroplasty (VBG) is a purely restrictive procedure.
In this procedure the upper stomach near the esophagus is stapled
vertically for about 2-1/2 inches (6 cm) to create a smaller stomach
pouch. The outlet from the pouch is restricted by a band or ring that
slows the emptying of the food and thus creates the feeling of fullness.
Advantages
- The primary advantage of this restrictive procedure is that a
reduced amount of well-chewed food enters and passes through the digestive
tract in the usual order. That allows the nutrients and vitamins
(as well as the calories) to be fully absorbed into the body.
- After 10 years, studies show that patients can maintain 50% of
targeted excess weight loss.
Risks
- Postoperatively, stapling of the stomach carries with it the risk
of staple-line disruption that can result in leakage and/or serious
infection. This may require prolonged hospitalization with antibiotic
treatment and/or additional operations.
- Staple-line disruption may also, in the long-term, lead to weight
gain. For these reasons, some surgeons divide the staple-line wall
of the pouch from the rest of the stomach to reduce the risk of long-term
staple-line disruption.
- The band or ring applied may lead to complications of obstruction
or perforation, requiring surgical intervention.
- Characteristically, these procedures, while creating a sense of
fullness, do not provide the necessary feeling of satisfaction that
one has had "enough" to eat.
- Because restrictive procedures rely solely on a small stomach
pouch to reduce food intake, there is the risk of the pouch stretching
or of the restricting band or ring at the pouch outlet breaking or
migrating, thus allowing patients to eat too much.
- Around 40% of patients undergoing these procedures have lost less
than half their excess body weight.
- As is the case with all weight loss surgeries, readmission to
a hospital may be required for fluid replacement or nutritional support
if there is excessive vomiting and adequate food intake cannot be
maintained.
Malabsorptive Procedures - Biliopancreatic Diversion
While these operations also reduce the size of the stomach, the stomach
pouch created is much larger than with other procedures. The goal
is to restrict the amount of food consumed and alter the normal digestive
process, but to a much greater degree. The anatomy of the small intestine
is changed to divert the bile and pancreatic juices so they meet the
ingested food closer to the middle or the end of the small intestine.With
the three approaches discussed below, absorption of nutrients and
calories is also reduced, but to a much greater degree than with previously
discussed procedures. Each of the three differs in how and when the
digestive juices (i.e., bile) come into contact with the food.
Since food bypasses the duodenum, all the risk considerations discussed
in the gastric bypass section regarding the malabsorption of some
minerals and vitamins also apply to these techniques, only to a greater
degree.
Biliopancreatic Diversion (BPD)
BPD removes approximately 3/4 of the stomach to produce both restriction
of food intake and reduction of acid output. Leaving enough upper
stomach is important to maintain proper nutrition. The small intestine
is then divided with one end attached to the stomach pouch to create
what is called an "alimentary limb." All the food moves
through this segment, however, not much is absorbed. The bile and
pancreatic juices move through the "biliopancreatic limb,"
which is connected to the side of the intestine close to the end.
This supplies digestive juices in the section of the intestine now
called the "common limb." The surgeon is able to vary the
length of the common limb to regulate the amount of absorption of
protein, fat and fat-soluble vitamins.
Extended (Distal) Roux-en-Y Gastric Bypass (RYGBP-E)
RYGBP-E is an alternative means of achieving malabsorption by creating
a stapled or divided small gastric pouch, leaving the remainder of
stomach in place. A long limb of the small intestine is attached to
the stomach to divert the bile and pancreatic juices. This procedure
carries with it fewer operative risks by avoiding removal of the lower
3/4 of the stomach. Gastric pouch size and the length of the bypassed
intestine determine the risks for ulcers, malnutrition and other effects.
Biliopancreatic Diversion with "Duodenal Switch"
This procedure is a variation of BPD in which stomach removal is restricted
to the outer margin, leaving a sleeve of stomach with the pylorus
and the beginning of the duodenum at its end. The duodenum, the first
portion of the small intestine, is divided so that pancreatic and
bile drainage is bypassed. The near end of the "alimentary limb"
is then attached to the beginning of the duodenum, while the "common
limb" is created in the same way as described above.
Advantages
- These operations often result in a high degree of patient satisfaction
because patients are able to eat larger meals than with a purely restrictive
or standard Roux-en-Y gastric bypass procedure.
- These procedures can produce the greatest excess weight loss because
they provide the highest levels of malabsorption.
- In one study of 125 patients, excess weight loss of 74% at one year,
78% at two years, 81% at three years, 84% at four years, and 91% at
five years was achieved.
- Long-term maintenance of excess body weight loss can be successful
if the patient adapts and adheres to a straightforward dietary, supplement,
exercise and behavioral regimen.
Risks
- For all malabsorption procedures there is a period of intestinal adaptation
when bowel movements can be very liquid and frequent. This condition
may lessen over time, but may be a permanent lifelong occurrence.
- Abdominal bloating and malodorous stool or gas may occur.
- Close lifelong monitoring for protein malnutrition, anemia and bone
disease is recommended. As well, lifelong vitamin supplementing is
required. It has been generally observed that if eating and vitamin
supplement instructions are not rigorously followed, at least 25%
of patients will develop problems that require treatment.
- Changes to the intestinal structure can result in the increased risk
of gallstone formation and the need for removal of the gallbladder.
- Re-routing of bile, pancreatic and other digestive juices beyond the
stomach can cause intestinal irritation and ulcers.
Gastric Bypass Roux-en-Y
In recent years, better clinical understanding of procedures combining
restrictive and malabsorptive approaches has increased the choices
of effective weight loss surgery for thousands of patients. By adding
malabsorption, food is delayed in mixing with bile and pancreatic
juices that aid in the absorption of nutrients. The result is an early
sense of fullness, combined with a sense of satisfaction that reduces
the desire to eat.
According to the American Society for Bariatric Surgery and the National
Institutes of Health, Roux-en-Y gastric bypass is the current gold
standard procedure for weight loss surgery. It is one of the most
frequently performed weight loss procedures in the United States.
In this procedure, stapling creates a small (15 to 20cc) stomach pouch.
The remainder of the stomach is not removed, but is completely stapled
shut and divided from the stomach pouch. The outlet from this newly
formed pouch empties directly into the lower portion of the jejunum,
thus bypassing calorie absorption. This is done by dividing the small
intestine just beyond the duodenum for the purpose of bringing it
up and constructing a connection with the newly formed stomach pouch.
The other end is connected into the side of the Roux limb of the intestine
creating the "Y" shape that gives the technique its name.
The length of either segment of the intestine can be increased to
produce lower or higher levels of malabsorption.
Advantages
- The average excess weight loss after the Roux-en-Y procedure is generally
higher in a compliant patient than with purely restrictive procedures.
- One year after surgery, weight loss can average 77% of excess body
weight.
- Studies show that after 10 to 14 years, 50-60% of excess body weight
loss has been maintained by some patients.
- A 2000 study of 500 patients showed that 96% of certain associated
health conditions studied (back pain, sleep apnea, high blood pressure,
diabetes and depression) were improved or resolved.
Risks
- Because the duodenum is bypassed, poor absorption of iron and calcium
can result in the lowering of total body iron and a predisposition
to iron deficiency anemia. This is a particular concern for patients
who experience chronic blood loss during excessive menstrual flow
or bleeding hemorrhoids. Women, already at risk for osteoporosis that
can occur after menopause, should be aware of the potential for heightened
bone calcium loss.
- Bypassing the duodenum has caused metabolic bone disease in some patients,
resulting in bone pain, loss of height, humped back and fractures
of the ribs and hip bones. All of the deficiencies mentioned above,
however, can be managed through proper diet and vitamin supplements.
- A chronic anemia due to Vitamin B12 deficiency may occur. The problem
can usually be managed with Vitamin B12 pills or injections.
- A condition known as "dumping syndrome " can occur as the
result of rapid emptying of stomach contents into the small intestine.
This is sometimes triggered when too much sugar or large amounts of
food are consumed. While generally not considered to be a serious
risk to your health, the results can be extremely unpleasant and can
include nausea, weakness, sweating, faintness and, on occasion, diarrhea
after eating. Some patients are unable to eat any form of sweets after
surgery.
- In some cases, the effectiveness of the procedure may be reduced if
the stomach pouch is stretched and/or if it is initially left larger
than 15-30cc.
- The bypassed portion of the stomach, duodenum and segments of the
small intestine cannot be easily visualized using X-ray or endoscopy
if problems such as ulcers, bleeding or malignancy should occur.
Laparoscopic or Minimally Invasive Surgery
For the last decade, laparoscopic procedures have been used in a variety
of general surgeries. Many people mistakenly believe that these techniques
are still "experimental." In fact, laparoscopy has become
the predominant technique in some areas of surgery and has been used
for weight loss surgery for several years. Although few bariatric
surgeons perform laparoscopic weight loss surgeries, more are offering
patients this less invasive surgical option whenever possible.
When a laparoscopic operation is performed, a small video camera is
inserted into the abdomen. The surgeon views the procedure on a separate
video monitor. Most laparoscopic surgeons believe this gives them
better visualization and access to key anatomical structures.
The camera and surgical instruments are inserted through small incisions
made in the abdominal wall. This approach is considered less invasive
because it replaces the need for one long incision to open the abdomen.
A recent study shows that patients having had laparoscopic weight
loss surgery experience less pain after surgery resulting in easier
breathing and lung function and higher overall oxygen levels. Other
realized benefits with laparoscopy have been fewer wound complications
such as infection or hernia, and patients returning more quickly to
pre-surgical levels of activity.
Laparoscopic procedures for weight loss surgery employ the same principles
as their "open" counterparts and produce similar excess
weight loss. Not all patients are candidates for this approach, just
as all bariatric surgeons are not trained in the advanced techniques
required to perform this less invasive method. The American Society
for Bariatric Surgery recommends that laparoscopic weight loss surgery
should only be performed by surgeons who are experienced in both laparoscopic
and open bariatric procedures.
