Duodenal
obstruction
Duodenal obstruction in the adult is usually due to malignancy, and
cancer of the pancreas is the most common cause. About one-third of patients
with pancreatic cancer treated by endoscopic stenting will develop obstruction.
Treatment is by gastroenterostomy. In patients having a surgical biliary bypass
for pancreatic cancer gastric drainage may be necessary.
A
variety of other malignancies can cause duodenal obstruction including
metastases from colorectal and gastric cancer. Primary duodenal cancer is much
less common as a cause of obstruction than these other malignancies.
Annular
pancreas may rarely cause duodenal obstruction. Obstruction usually follows an
attack of pancreatitis and on occasions the obstruction may be mistaken for
malignancy. Arteriomesenteric compression is an ill-defined condition in
which it is proposed that the fourth part of the duodenum is compressed between
the superior mesenteric artery and the vertebral column. Where it is
convincingly demonstrated and causing weight loss duodenojejunostomy may be
performed.
Gastroplasty
for morbid obesity
A number of surgical treatments has been devised for morbid obesity, but
of these the most commonly used is the vertical banded gastroplasty (Mason).
Some surgeons prefer a gastric bypass operation which has some similarities.
Indeed, gastric bypass can be used as a revisional procedure following stomal
obstruction, one of the more common complications of gastroplasty.
Indications
for operation
Selection of patients for operation should ideally be made by a team
that includes a nutritionist/endocrinologist and a psychiatrist, as well as a
surgeon, as it is important that major metabolic problems and severe psychiatric
disorders are elucidated before operation. The patient should be 100 per cent
over their ideal weight for height or have a body mass index [weight (kg)/height
(in)2] of greater than 45. This figure is selected because the
increase in morbidity and mortality at this level of obesity is excessive. Very
often the patient will have some of the morbidity associated with severe obesity
such as hypertension, diabetes or osteoarthritis. Preoperative counselling
should include discussion of the possibility of perioperative mortality (which
is in the region of 1—4 per cent). This is very much an elective procedure and
the patient is at risk of postoperative respiratory problems and pulmonary
thromboembolism. Intensive or high-dependency care facilities must be
available.
Operation
The operation is performed under general anaesthesia and the addition of
an epidural greatly aids both the perioperative and postoperative management.
The procedure should be undertaken by an anesthetist very experienced in this
area.
The
abdomen is opened from the midline incision and adequate retraction provided to
gain access to the upper part of the stomach. Approximately 50 per cent of
patients will already have gallstones and, if this is the case, cholecystectomy
should be carried out. Some surgeons advocate prophylactic cholecystectomy but
this is difficult to substantiate. A large orogastric tube is placed in the
stomach and the lesser sac is opened through the greater omentum by careful
blunt dissection. A window is made between the lateral side of oesophagus and
the lesser sac (Fig. 51.35). It is important to take great care during
this part of the operation to avoid damaging the spleen or short gastric
arteries. Once this has been carried out it is convenient to place a tape
through this window to avoid losing access. A position is selected on the
anterior wall of the stomach above the level of the incisura. A circular stapler
with the head removed and the spike inserted is placed in the lesser sac with
edge of the instrument up against the tube in the stomach. The handle of the
stapler is then rotated to introduce the spike through the front and back wall
of the stomach. Once this has been done the spike can be removed and the anvil
of the stapler inserted in the usual fashion. Tightening up and firing the
stapler produces a stapled circular defect in the mid body of the stomach with
the space about 15 mm between the lesser curve and the window. Following this a
stapler, such as the Auto suture TA90B, is inserted through the circular window
and through the gap made at the lateral side of the oesophagus. This instrument
is particularly recommended as it places four rows of staples in the stomach (Fig. 51.35) which greatly reduces the possibility of
staple line disruption. These manoeuvres lead to the creation of a pouch of
about 30 ml, the volume being checked before the linear stapler is fired. It is
then important to band the outlet of this pouch to avoid dilatation with time. A
number of materials may be used including polypropylene mesh and expanded
polytetrafluoroethylene (PTFE). Whatever material is used, the width should be
approximately 1.5 cm and the circumference of the band about 5 cm. It has
been shown in a variety of studies that if the band has a larger circumference
than this there is a high incidence of inadequate weight loss, and if it made as
small as 4.5 cm there is a high incidence of stomal stenosis. The exact
dimensions of the band, however, are a critical part of the operation and the
experience of the surgeon will often subtly alter the band circumference.
Postoperatively
the patients should be managed on an intensive care or a high-dependency care
unit until the possibility of apnoea and other complications is diminished.
Epidural anaesthesia is useful as it avoids the amount of opiate given to the
patient. The patient may be introduced to fluids on the first postoperative day
and small quantities of food around the fourth or fifth day. Dietary advice is
very important at this point. It is important that the patient understands that liquidized
food or high-calorie supplements ate to be avoided and that only
small quantities of food are to be eaten to avoid blocking the narrow pouch
outlet.
Patients
can be expected to lose between a third and a half of their body weight in the 2
years following operation. Over this period it is advisable to take a vitamin
supplement to avoid deficiencies which may otherwise occur. Following the first
2 years it is possible for the patient to begin weight gain, and it is important
that they understand that moderation and self-control will be necessary in the
long term. This is often possible because after 2 years the patient’s eating
habits have been quite radically changed and the apparently insurmountable task
of losing almost a half of their body weight has been overcome.
Complications
Pulmonary embolism is a risk for all such patients and hence they should
be managed with adequate doses of prophylaxis (5000 units of heparin tid).
Although it might be expected that wound herniation would be a common sequel of
this operation, in practice if the abdominal wound is repaired well with a
continuous nonabsorbable suture such problems are uncommon. As with any
procedure that involves opening the gastrointestinal tract, prophylactic
antibiotics are important. Unlike small bowel bypass, vertical banded
gastroplasty is not associated with major metabolic consequences or liver
disease. The two commonest long-term complications are inadequate weight loss,
which usually relates either to technical aspects of the procedure or to patient