L3 - Parenteral nutrition

Question 1

IV vs EN nutrition – 3

Answer 1

1. Fluid regimens don’t provide essential requirements, so IV replaced by EN for patients needing a healthy diet.
2. Enteral access decided if tube for short or long-term.
3. Nasoenteric (nose) feeding common & nasogastric tubes able to quantify gastric residuals. Also less likely to be clogged but are less comfortable

Question 1

Enteral nutrition - 3

Answer 1

1. EN (enteral nutrition) is generally indicated for patients that are unable to obtain adequate nutrition by mouth but who have a functioning gut.
2. EN routes include through nasogastric, nasojejunal, gastrostomy or jejunostomy tubes.
3. EN routes also maintain healthy gut function until normal feeding is resumed.

Question 2

The choice of EN or PN in critically ill adult patients - 3

Answer 2

1. EN vs PN results in decrease in incidence of infectious complications
2. PN associated w/ higher incidence of hyperglycaemia
3. EN 1st choice because its cheaper, & less risk of infection

Question 3

Parenteral nutrition – 3

Answer 3

1. PN is used for long-term nutritional support (>7 days) when patients:
   Can’t receive nutrition through oral or enteral or have severe gut dysfunction
2. May also contain drugs
3. Indications: PN is required for patients with conditions like massive bowel resection, severe malnutrition, short bowel syndrome, non-functional gut, inflammatory bowel disease, cancer, etc.

Question 4

TPN & PPN – 4

Answer 4

1. All nutrition is provided via IV, bypassing GIT processes of eating & digestion
2. Depending on type of parenteral nutrition solution used i.e. Total parenteral nutrition (TPN) or partial parenteral nutrition (PPN), may be given either centrally (TPN, PPN) or peripherally (IV).
3. Mechanical pump delivers nutrition intravenously - may be utilized as an inpatient or at home.
4. Monitoring is required to regularly evaluate:
   - body weight; Complete blood count (CBC)/electrolytes/blood urea nitrogen (BUN)
   - Glucose; intake/output; liver function tests

Question 5

TPN Fluid volume - 3

Answer 5

1. Prior & during TPN, fluid status assessment is imperative.
   Fluid requirements are:
2. Increased in fever, fistulas, vomiting & diarrhoea, nasogastric (NG) suction, unusual fluid losses from burns, stomas & wound drains.
3. Decreased in renal failure, congestive hear failure, Cirrhotic ascites & pulmonary disease.

Question 6

Dextrose rate in PN - 3

Answer 6

1. Supplies energy - can replace need for glucose
2. When infused through a central (large) [vein] up to 50% can be administered
3. Best given w/ appropriate lipid to reduce incidence of hyperglycaemia, hypercapnia (abnormal CO2 retention), fatty liver & acidosis.

Question 7

Lipids in PN - 6

Answer 7

1. For energy supply, usually in the form of a lipid emulsion
2. Reduces need for excessive vol or str of glucose & associated-complications
3. Lowering of osmolality of feeding solution may permit peripheral rather than central administration of the regimen
4. Lipid emulsions traditionally long chain triglycerides, can give mix of medium & long chain triglycerides (less derangement of liver function tests), but long chain is more stable (better for mixtures).
5. Stability of IV fat emulsion decreased when added to 3-in-1 PN mixtures (dextrose, amino acids & fatty emulsion) leads to cracking of the emulsion
6. Fat emulsion usable for paediatric & neonatal patients. Caution in neonates because low rates of clearance & potential accumulation in lungs.

Question 8

Nitrogen in PN - 2

Answer 8

1. For protein supply, addition of amino-acid solution buffers the suspension.
2. Sufficient calories must be provided alongside the AAs in PN regimen to prevent their use for energy;

Question 9

AIO TPN - 3

Answer 9

1. Creating an All-in-One (AIO) formulation safely, effectively & in a low-risk method can provide: AA, carbohydrates, lipids & micronutrients e(.g. vitamins, electrolytes)
2. Balanced TPN (Total Parenteral Nutrition) circumvents the problems of overfeeding & high blood sugar levels leading to weight gain & insulin resistance;
3. AIO admixtures also reduce the risk of error & contamination.

Question 10

Concepts of AIO mixtures in TPN: Single bag Possible reactions - 4

Answer 10

Possible reactions:
1. creaming & coalescence of a fat emulsion due to change of pH or acidity of AA & glucose mix
2. sugars & AAs may react causing loss of AAs
3. occurrence of precipitates of electrolytes; e.g. lipid peroxide - needs monitoring
4. a non-preferred change in pH.

Question 11

Compatibility & stability of TPN admixtures

Answer 11

AAs can have protective effect via buffering capacity