Intestinal
Failure And Assessment
Intestinal failure
Intestinal failure means that the patient can no longer
maintain their nutritional needs by oral intake of food. In some patients, for
example those who have had a recent bowel resection, this is a temporary state
that will recover as the residual bowel adapts; in others with very diseased
bowel or major resections the condition may be irreversible with a continued
requirement for parenteral nutrition (PN).
Parenteral nutrition is the main treatment for patients
with intestinal failure. It requires an indwelling central venous catheter to
which the patient connects a bag of nutrition (typically 2.5 litres) every
evening to run over 12 to 14 hours through the night. Most patients can live a
reasonable existence on such therapy.
Complications of parenteral nutrition
The 1-year survival of a patient on home PN is 90%,
falling to 65% at 5 years. There are three principal complications of long-term
PN.
Catheter-related sepsis
The central venous catheter may become infected during
the course of setting up or taking down the PN infusion, or if the catheter is
damaged. Sepsis may remain line-associated or may result in infective
endocarditis or other disseminated infection.
Venous thrombosis
Indwelling cannulas are associated with venous
thrombosis, with loss of that central vein for future access. Patients
predisposed to thrombosis may rapidly lose their internal jugular veins or even
thrombose the superior vena cava (SVC), necessitating a cannula in a femoral
vein or, via direct translumbar puncture, in the inferior vena cava (IVC).
Extensive venous thrombosis may preclude transplanta- tion, so early referral
as venous access diminishes is important.
Intestinal failure associated liver disease (IFALD)
Liver disease affects over half of patients on long-term
PN, although it may start before PN is instituted in the very malnourished
patient. In children, this is commonly due to cholestasis, in adults it is
usually steatohepatitis. Steatohepatitis is probably a consequence of the high
glucose intake, stimulating insulin production which promotes lipogenesis,
combined with high lipid infusions. In both groups the disease may progress to
fibrosis and cirrhosis.
Biliary sludge and gallstones are common in both age
groups, and is associated with short bowel syndrome in the absence of PN.
Other factors predicting poor outcome on PN
The other factors associated with a poor outcome on PN
are age (children, and adults over 60); extremely short length of residual
bowel (<50 cm); dysmotility disorders; radiation enteritis; and longer
duration of treatment.
Indications for transplantation
Intestinal transplantation is indicated for one of three
main reasons.
1.
Complications of
parenteral nutrition (PN):
· PN-induced liver injury;
· thrombosis of two or more
central veins;
· two or more episodes of
catheter-related sepsis per year requir- ing hospitalisation;
· a single episode of
fungal catheter-related sepsis; septic shock;
· frequent severe
dehydration due to gut losses despite intravenous fluid supplementation and
PN.
2. Requirement for major gut resection for tumour, such as a desmoid tumour
invading the mesentery.
3. Unacceptable quality of life on PN.
Assessment for transplantation
There are three main aspects to the assessment of
intestinal transplant recipients.
Fitness for surgery
Multivisceral transplantation is akin to liver
transplantation in its surgical stress. Full cardiological and respiratory
assessments are performed. Since kidney failure is common post-intestinal
trans- plantation and is difficult to assess in patients on PN, a nuclear medicine
glomerular filtration rate (GFR) measurement is required to gauge the need for
simultaneous kidney transplantation.
Extensive venous mapping is usually required to identify
sites for peri-operative access. The presence of SVC thrombosis is a contraindication
to a liver transplant using a classical caval replacement technique, because
this would remove all venous return to the heart. At least one femoral vein
needs to be patent, with patency of the IVC.
A preferred site for a stoma should be marked, and the
patient should receive appropriate stoma counselling.
Patients undergoing modified or full multivisceral
transplantation will undergo splenectomy as part of the explant procedure.
They should therefore be immunised against meningococcus, pneumococcus and
haemophilus influenza before listing.
Extensive psychological assessment is required,
particularly of anyone undergoing the procedure only for quality-of-life.
Liver disease
Is there any evidence of underlying liver disease?
Imaging, including duplex ultrasound of the liver, and liver biopsy are usually
required in addition to liver biochemistry to assess whether the liver is
affected by IFALD, and if so, whether it needs replacing.
Surgical anatomy
Previous surgical history detailing any and every
resection is important to enable judgement as to what is feasible. This is
supplemented by contrast imaging of the remaining bowel, together with
endoscopic inspection of any bowel to be left in situ to exclude disease, and
also inspection of any bowel to be removed to confirm the diagnosis if
required.
Three-dimensional imaging of the gut is particularly
important in the case of malignancy to allow estimation of the extent of the
tumour. Desmoids, the commonest malignancy for which trans- plantation is
undertaken, are associated with intestinal polyposis (Gardner syndrome) and
usually arise within the mesentery and extend to the adjacent structures, such
as the abdominal wall, renal tract or great vessels in the retroperitoneum. All
residual tumour should be removed.
Results of intestinal transplantation
Outcomes following intestinal transplantation vary, and
are better in centres with high-volume programmes, in younger recipients and in
patients transplanted from home rather than in those who were inpatients
already. Overall graft survival rates are around 80% and patient survival rates
are around 90% at 1 year.
