Journal of Hematology - Supplements - Haematologica

60
patients, the major risks are electrolyte and glucose
disturbances, sometimes also related to
complications of the underlying disease. In longterm
parenterally-fed patients, the risk of developing
micro- and macronutrient deficiencies
must be taken into account, because of the difficulty
in providing an adequate and complete PNadmixture.
In bone marrow transplanted
patients, the major deficiency risk is related to
the limited administration of lipids, often not
given because of sespis, and pharmacologic
incompatibility with other therapies. In children
EFA-deficiency can be detected after 1 week
without a EFA intake that is at least 1% of the
total daily calorie intake; linoleic and linolenic
acids are not synthesized by humans and are
both considered essential; they are the precursors
of arachidonic acid (from linoleic) and of
docosahexaenoic and eicosapentaenoic acids
(from linoleic acid), which are involved in central
nervous system development. These essential
fatty acids are necessary for growth, skin and
hair integrity, regulation of cholesterol metabolism,
decreased platelet aggregation, and
lipotropic activity. The parenteral lipid emulsions
are represented by long chain fatty acids
(LCT), by a mixture of long and medium chain
triglycerides (LCT-MCT), and by the more recent
olive oil derivates. Their use is often limited
because of concern about the effects on immune
and reticulo-endothelial systems, by the mediation
of several systems, including increasing E2
production, decreasing T helper / T suppressor
ratio, inhibiting neutrophil migration, chemotaxis,
endotoxin clearance, and complement
synthesis and depressed natural killer and lymphokine
activated killer activity by blockage of
interleukin-2 binding to its receptor. 2,4
PN solution means a complete admixture of at
least glucose, nitrogen, salts, minerals; the provision
of glucose and salts is not parenteral nutrition,
but hydration support. Lipids need not be
given daily, but they must be given one/two days
a week in order to cover basal needs; zinc and
copper supplementation will be required if PN
lasts for more than 2 week, while complete provision
of all known trace elements is strongly indicated
for PN of longer duration, in order to avoid
a deficiency syndrome. The complexity of a PN
solution grows with the duration of the artificial
support, particularly if nutrition is exclusively
being given by the pare-nteral route, i.e. in
patients who cannot eat even small amounts of
food. The definition of parenteral intakes is based
on the metabolic status of the patient (presence
of hypercatabolism and/or malnutrition) and on
theoretical calorie and nitrogen needs; the intakes
must be closely monitored to avoid the most frequent
complications. In critically ill patients, a
constant infusion rate generally allows better
metabolic tolerance, especially for lipids, which
must be delivered over at least 8-12 hours in
order to reduce the risk of hypertriglyceridemia
which can occur if the infusion rate exceeds clearance
capacity (the infusion rate should be a maximum
of 0.17 g/kg/h). 2
The use of glutamine, a conditionally-essential
aminoacid, has been claimed to be important
in decreasing mortality and morbidity in
patients undergoing bone marrow transplantations,
as well as in other clinical conditions. Its
role in muscle function, in nitrogen transport to
the cells, as a primary fuel for enterocytes, and
in preserving the integrity of mucosal structure
and function of the intestine, appear to be crucial
and many clinical trials have been performed
in order to demonstrate its effect, given either
parenterally or orally. There is, however, no clear
evidence so far that glutamine is useful in
improving outcome in these patients and its use
needs further investigation. 3
Liver disease is a main metabolic complication
of PN, but can occur in any cancer patient due
to therapy or to graft-versus-host disease. Its
best prevention is avoidance of prolonged enteral
fasting, infections, and surgery. As far as concerns
the PN admixture, the lower the calorie
content, the lower the probability of developing
liver disease: as a rule, calorie intake should not
exceed the (theoretical) needs, so as to reduce
the risk of hepatic fat deposition. The evolution
toward severe liver damage is more frequent in
low-birth weight neonates and in children on
long-term parenteral nutrition (months, years).
This having been said, in any given situation it is
more likely that liver involvement is related to
the underlying disease than to well-conducted
parenteral nutrition. 1,2,6
In conclusion, even in the absence of RCT
clearly demonstrating its efficacy on disease outcome,
artificial nutritional support seems to be
useful in bone marrow transplanted patients in
order to avoid or correct malnutrition, which is
a frequent and multifactorial complication of
the procedure. An experienced team (nurses,
surgeon, pediatrician, pharmacist) is the best
preventive measure against technical and metabolic
complications.
References
1. A.S.P.E.N. Board of Directors. Guidelines for the use
of parenteral and enteral nutrition in adult and pediatric
patients. JPEN 1993; 17:1SA- 38SA.
2. Candusso M. Nutrizione del bambino ospedalizzato:
principi e pratica. M&B 2000; 19:289-94.
3. Demirer S, Aydintug S, Ustun C, et al. Comparison of
the efficacy of medium chain triglycerides with long
haematologica vol. 85(supplement to n. 11):November 2000