Total Parenteral Nutrition

Question 1

TPN

Answer 1

Process of supplying nutrients via the IV route

Question 2

Indications

Answer 2

Patients whose GIT are not functional
Undernourished patients who cannot ingest large volumes of oral feedings and being prep for surgery, radiation therapy or chemotherapy
Disorders requiring complete bowel rest - CD, UC, severe pancreatitis
Paediatric GI disorder - congenital anomalies, prolonged diarrhoea

Question 3

Composition

Answer 3

Carbohydrates
Amino Acids
Lipid

Question 4

Types

Answer 4

Solutions without lipids: 2-in-1
Solutions with lipids: 3-in-1

Question 5

Aqueous TPN: 2-in-1

Answer 5

Contains - amino acids, carbohydrates, electrolytes, ± water soluble vitamins and ± trace elements
Advantages - stability is longer. Used for neonatal and paediatric patients
Disadvantages - Risk of sepsis is high
Expiration: 21 days

Question 6

All in 1: 3-in-1

Answer 6

Contains - lipids, amino acids, carbohydrates, electrolytes, ± water soluble vitamins, ± fat soluble vitamins, and ± trace elements
Advantages - less administration time for nurses. potentially reduced risk of sepsis
Disadvantages - precipitation cannot be seen, short expiration date, phase separation
Expiration - 7 days

Question 7

Challenges

Answer 7

Precipitation
Chemical reactions of components
Degradation of nutrient concentration
Emulsion instability

Question 8

Precipitation

Answer 8

Addition of electrolytes, trace elements and vitamins can lead to precipitation
Can result to physical incompatibilities
Significant cause - excessive concentrations of calcium phosphate
Solution - use of organic salts e.g. gluconates and glycerophosphates

Question 9

Chemical reactions

Answer 9

Amino acids and glucose interaction - forming Maillard reaction
Reaction rate is temperature dependent

Question 10

Degradation of nutrient concentration

Answer 10

Peroxidation - responsible for complications occuring in premature infants e.g. bronchopulmonary dysplasia and retinopathy
Solution - administering vitamins in lipid emulsion to benefit from the anti-oxidative activity of vitamin C and E

Question 11

Drug stability

Answer 11

Other drugs are likely to be given to patients alongside TPN
Some drugs are compatible and can be added to the TPN bag however most are not compatible
Pharmaceutical interaction - precipitation, colour change or phase separation
Pharmacokinetic and Pharmacodynamic interactions - drug protein binding degree changes, CYP450 activity modification

Question 12

Emulsion instability

Answer 12

Lipid emulsions are thermodynamically unstable - two phases tend to separate over time
Visible phase can be reversible
Coalescene of lipid globules are irreversible

Question 13

Improving TPN stability

Answer 13

TPN are packaged in two or three compartment bags

Question 14

Multichamber bags (MCB)

Answer 14

Increase the stability and shelf life of TPN
The individual chamber seals were broken to mix the chamber contents upon use

Question 15

Contraindications

Answer 15

Egg allergy
Hyperlipidaemia
Coagulopathy
Thrombocytopenia

Question 16

Complications

Answer 16

Central venous catheter - pneumothorax, infection, arterial puncture
Glucose abnormalities - hyperglycaemia and hypoglycaemia
Hepatic - liver dysfunction, painful hepatomegaly