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Which Procedure Is
Right For You?
Anatomic, Physiologic and Patient considerations
in selecting the appropriate intervention for patients with morbid
obesity:
The most important factor in achieving success in bariatric
surgery is patient selection and intervention selection. Most
patients who present for evaluation for bariatric surgical
procedures are self-referred, determined to achieve change, and
willing to make personal life-long sacrifices to achieve their
goals. Candidates who are not self-referred, reluctant, uncertain,
and attached to certain eating behaviors are to be counseled
extensively before proceeding to surgery. Once you have determined
that the patient is in the first of the above two categories, or
after extensive counseling, therapy as needed, and appropriate
time you have succeeded in establishing that the patient belongs
to the former category, the next step is education.
Education:
Anatomic and Historically Known Considerations:
Click here to view anatomy of the
stomach
The esophagus is the first passageway
into the stomach. History tells us that interventions above or at
the level of the esophagus are not effective for the treatment of
morbid obesity. For example, wiring the teeth shut is ineffective
because the patient's nutritional source is liquid and shakes.
Rapidly, patients consume such high calorie liquids and reach
their homeostatic or baseline level of nutritional intake and
therefore do not loose weight. The Angelchick prosthesis of the
past taught us that obstructive devices on the esophagus were
frought with complications such as erosion, and esophageal
dilation and are therefore not an option.
The EG junction and its physiologic function to relax for
food passage and tighten to prevent reflux is important. In
patients with significant reflux disease, certain operations
should be avoided.
The fundus of the stomach has a thin wall and a great
propensity to stretch. Prior historical experience tells us to
avoid using this portion of the stomach in the formation of a
pouch because of this propensity.
The body of the stomach produces acid and has muscular
digestive function as well for mixing chyme.
The lesser curvature of the stomach is the thicker walled
portion of the stomach, has lesser propensity to stretch, and is
more fixed in position.
The pylorus is the outlet of the stomach and is important
in regulating the output of the stomach so as to properly limit
acid output to the duodenum, control chyme and other fluid output
from the stomach, and prevent bile reflux between meals.
Denervation of the pylorus results in spasm and obstruction here,
and disabling (pyloroplasty or pyloromyotomy) or bypassing the
valve (as with the Roux-en-Y Gastric Bypass - RNY-GB - procedure)
results in dumping syndrome because of unregulated emptying of
high solute concentration liquids (specifically sweets) into the
small bowel.
The antrum is the lower 1/3 of the stomach. It is important
for two main reasons. First, it harbours G cells that secrete
gastrin. This is a paracrine and endocrine hormone that stimulates
acid production. This is important when considering the larger
pouch of the Scopinaro BPD where the endocrine gastrin effects can
increase pouch acid production and increase the rate of
ulceration. This is why a distal gastrectomy is recommended with
larger pouch procedures.
The acid is also important when considering the duodenal
switch procedure where preservation of antral acidification helps
convert dietary iron to its absorbable oxidized ferric form.
Parietal cells in the antrum also produce an intrinsic factor, a
protein necessary for B12 absorption in the ileum.
The duodenum is important in the secretion of a number of
hormones including secretin, cholecystokinin, and enteroglucagon.
Leaving the duodenum within the digestive food channel is believed
to allow for more normal GI hormonal response to meals which is
felt to provide improved physiologic response to meals and
improved satisfaction.
The bile duct, main pancreatic duct and accessory
pancreatic ducts are shown to illustrate the anatomic and surgical
hazards associated with performance of the duodenal switch
procedure, and to allow for an understanding of its mechanism. The
portions of the small bowel are shown with their approximate
lengths (unstretched) to allow also for understanding the lengths
of intestinal tract used in various parts of the available
surgical procedures.
The Simplified Basics of Weight Balance:
The concept of weight balance or caloric equilibrium is based on
the concept of basal metabolic rate mandating that each individual
has a certain daily caloric need that will result in neither
weight gain (anabolism) nor weight loss (catabolism). For most
people this is about 1800 calories per day. For some it is lower,
for others higher.
Patients who have gained excess body weight, have done so by
caloric intake that exceeds their daily caloric need on a daily
basis for a sustained period of time. If weight gain is on-going,
then this excess intake is on-going. Weight loss requires that
intake (and/or absorption of intake) be reduced below metabolic
need on a daily basis for a sustained period of time.
Balance is reached by this process when the patient's total body
size now requires less calories for maintenance, and that need is
met by the intake and absorption that the patient is capable of
achieving post-operatively. Weight loss therefore stops at this
equilibrium.
How then do we reduce the caloric intake of the patient? The best
approach is to determine where the EXCESS calories are coming from
and eliminate (restrict) that source or prevent that source of
excess calories from being absorbed (malabsorption). In order to
target these sources, we attempt to categorize patients' excess
caloric intake sources.
These excesses are categorized as follows:
1) "Bloating": over-eating, eating large meals
2) "Grazing": constant snacking during the day and between meals
or at night.
3) "Sweeting": frequent ingestion of high calorie simple sugar
containing foods/drinks/shakes
4) "Choosing": choosing the wrong foods at each meal (high fat,
fried, high carbohydrate, low fiber)
Patients are then asked to classify themselves to determine where
their excess calories have come from. If the patient reports that
they do not get excess calories currently, then when they were
getting excess calories, where did they come from in the past.
Most patients can classify themselves into one or two of the above
categories, for the most part. Patients who report that they have
had stable weight for over one year, are likely to be no longer
eating excess calories but rather have truly modified their diets
to reach balance. These patients are classified as normal to low
metabolizers depending on their reported caloric intake.
The first step in selection is education. The best judge of the
patient's need is the patient. The only limiting factor is the
patient's knowledge base. Once the patient determines their
classification, then an effective procedure can be chosen. This
process is accomplished with the patient. Other factors that play
into the decision include the patients weight loss goals, short
and long-term risk tolerance, and side-effect tolerance.
Flow Chart of Decision making:
Condition & Surgical Choice
Bloater
Choose: VBG, AGB, VG-Sleeve, or PRYGBP
Grazer
Avoid: VBG, AGB, VG-Sleeve Avoid: PGBP
May Choose: BPD, BPD-DS, MGBP, DGBP
Sweeter
Avoid: VBG, AGB, VG-Sleeve
May Choose: GBP, BPD, or BPD-DS
Chooser
May Choose: BPD or BPD-DS, MRYGBP, DGBP
Low Metabolizer
May Choose: BPD or BPD-DS, MGBP, DGBP
Weight loss goal 60-65%
May Choose:
PRYGBP, VBG, VG-Sleeve, AGB
Weight loss Goal 70-80%
May Choose: MRYGBP, BPD or BPD-DS
Weigh Loss Goal 90-100%
May Choose: DGBP at 1-2 years, BPD or BPD-DS at 3-4 yrs
Accepts High (10% -20%) long term risk of Vitamin or Protein
Malnutrition
May Choose: DRYGBP
Accepts Moderate (5-7%) long term risk of Vitamin or Protein
Malnutrition
Choose: BPD or BPD-DS
Desires Low (1-2%) long term risk of Vitamin or Protein
Malnutrition
Choose: PRYGBP
Desires No (<1%) long term risk of Vitamin or Protein Malnutrition
Choose: AGB, VG-Sleeve, or VBG
Chronically Iron deficient
Avoid all GBP and avoid BPD-Scopinaro
Choose BPD-DS
Osteoporosis or strong family history of this or at risk for this
Avoid BPD-Scopinaro and BPD-DS
Cannot accept weight regain risk of 20% at 3 years
Avoid PRYGBP
Abbreviations:
AGB
Adjustable Gastric Band
GBP
Gastric Bypass
M
Middle
D
Distal
BPD
Biliopancreatic Diversion
DS
Duodenal Switch
VBG
Vertical Banded Gastroplasty
VG/SG (or VG-Sleeve)
Vertical Gastroplasty with Sleeve Gastrectomy (Also known as
Magenstrasse-Mill Operation)
P
Proximal Roux-en-Y
BPD-DS
Biliopancreatic Diversion with Duodenal Switch (performed in
conjunction with Vertical Gastroplasty with Sleeve Gastrectomy)
EBWL
Excess body weight loss.
[i] (Cowan 1996), (Abu-Abied 2001), (Deitel 1999), (Glenny 1997).
[ii] (Macgregor 1998).
[iii] (WHO 1997).
source:
http://www.alagsa.com/Bariatric_Surgery.htm
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