TYPE OF FORMULAE IN PARENTERAL NUTRITION

1. TYPE OF FORMULA IN
PARENTERAL NUTRITION

2. PARENTERAL NUTRITION
Parenteral nutrition (PN) can be divided into:
 Total parenteral nutrition (TPN) – all nutrient needs are
covered by intravenous way without any significant enteral
intake.
 Supplementary parenteral nutrition – a patient receives some
part of his/her food via gastrointestinal tract and the rest is
infused parenterally.
The composition of parenteral nutrition and the intake of
particular nutrients must be planned carefully according to the
patient’s needs and metabolic capacities because:
 Food is absorbed only partially from the GI tract and absorption
of some nutrients (e.g. trace elements) is controlled in the bowel
to supply the patient’s needs.
 The patient receiving i.v. feed is not able to control absorption
all nutrients given intravenously must be metabolized,
assimilated or excreted.
 Overfeeding is easy during parenteral nutrition and can be
harmful.
 Patients requiring PN may suffer from organ failure or be
injured; metabolism of nutrients could be different from that of
healthy individuals.

3. TPN must be complete which means that all necessary nutrients (amino acids, carbohydrates,
fat, water, electrolytes, vitamins and trace elements) must be supplied in amounts required.
However, TPN gives us the unique possibility of adapting the intake of nutrients to the patient’s
needs by tailoring the nutritional formula depending on:
 Metabolic disturbances secondary to disease and/or organ dysfunction
 Coexisted deficiencies or overloading
 Indications to provide increased amounts of special substrates, which can influence
outcome because of their pharmacological properties (e.g. glutamine, u-3 fatty acids,
antioxidants, BCAA).
For exact planning of nutritional formula composition it is therefore important to:
 Recognize the metabolic status of the patient and the impact
 Estimate the patient’s requirements
 Determine the goal of treatment
PN formulas Each patient receiving parenteral nutrition must be controlled clinically and
metabolic changes must be monitored to an extent and with a frequency, which depend on the
clinical situation.
The composition of the parenteral nutrition must be modified accordingly.
 Peripheral formula should have low osmolarity in order to be tolerated by peripheral veins. For
that reason the volume and amount of fat are increased and the amount of electrolytes is limited to
basic requirement.

4.  Standard formula for central venous catheter may be given to most patients. One from the group of
ready-to-use two or three chamber bags may be chosen.
 In patients suffering from moderate stress protein intake is slightly increased; also the need for
electrolytes may be changed. Patients in severe stress could profit from glutamine addition and
increased amounts of zinc and selenium.
 In renal patients the dosage of water, electrolytes, trace elements and sometimes vitamins must
individualized, depending on degree of renal failure and renal replacement therapy. In dialysed patients
the protein intake may not be decreased and should follow the other clinical conditions.
 In patients with hepatic ercephalopathy the dosage of AA should be limited and special amino acid
solutions given. Because excretion of copper and manganese may be limited it is better to give only
basic amounts of zinc and selenium and not to use preparations containing a mixture of trace elements.
 Cardiac failure patients are at risk of water and sodium overload. Limitation of water and sodium
intake is therefore indicated. Severely malnourished patients are depleted in intracellular electrolytes
and therefore at risk of refeeding syndrome. They should receive increased amounts of potassium,
magnesium, vitamins and especially phosphate. Step by step increase in energy intake is indicated.
 Patients suffered from respiratory failure may benefit from decreased intake of glucose; therefore
the energy needs should be covered by increasing amount of fat.

5. REFERENCES
1. A.S.P.E.N. Board of Directors. Guidelines for the use of parenteral and enteral nutrition in adult and paediatric
patients. JPEN 1993;17(Suppl. 4).
2. National Advisory Group on Standards and Practice Guidelines for Parenteral Nutrition. Safe practices for
parenteral nutrition formulations. JPEN 1998;22:49.
3. Schloerb PR. Electronic parenteral and enteral nutrition. JPEN 2000;24:23.