Parenteral nutrition

Question 1

Describe the ASPEN definition of Parenteral Nutrition (PN) and mention the components it may include.

Answer 1

Parenteral nutrition (PN) involves intravenous administration of nutrients like protein, carbohydrate, fat, minerals, electrolytes, vitamins, and trace elements for patients unable to eat or absorb enough through tube feeding or orally. It’s important to note that not all PN formulations include fat, vitamins, and minerals.

Question 2

Do the limitations of the evidence base for Parenteral Nutrition (PN) focus on the criteria for inclusion and exclusion of subjects? Also, discuss whether quantity or route is a more significant concern in PN research.

Answer 2

The limitations of the evidence base for PN include

• issues with criteria for inclusion (e.g., reliance on albumin levels) and exclusion (e.g., excluding malnourished subjects or those for whom enteral nutrition is contraindicated).
• debate arises if quantity (overfeeding) rather than the route of administration is the primary concern in PN research.

Question 3

Outline the NICE (2006) guidelines on PN

Answer 3

Non surgical patients:

Malnourished/at risk + inadequate/unsafe oral/enteral intake + non functional/inaccessible/perforated GI tract - GRADE D

Surgical patients

Malnourished + inadequate/unsafe oral/enteral intake + non functional/inaccessible/perforated GI tract

GRADE B

Question 4

Define the indications for Parenteral Nutrition (PN) in surgical patients according to ESPEN 2009 guidelines. Explain when PN is considered beneficial and the preferred choice of nutrition in specific scenarios.

Answer 4

• PN is beneficial for undernourished patients unable to tolerate or receive enough enteral nutrition.
• Also recommended for patients with postoperative complications affecting GI function and inadequate oral/enteral intake for at least 7 days.

The first choice is enteral nutrition or a combination of enteral and supplementary PN.

Question 5

How does the choice between Parenteral Nutrition (PN) and Enteral Nutrition (EN) vary based on the patient’s condition and gut functionality? Explain the importance of regularly reviewing the choice of nutrition.

Answer 5

The decision between PN and EN depends on the patient’s symptoms and gut function. If the gut is partially functional, EN or oral intake should be encouraged. The choice between PN and EN should be regularly reassessed based on the patient’s condition, as it is a dynamic decision affected by gut functionality.

Question 6

Describe the significance of understanding the patient’s GI anatomy in determining the need for Parenteral Nutrition (PN). Explain how different types of bowel surgeries impact the absorption of nutrients.

Answer 6

Understanding the patient’s GI anatomy is crucial in deciding whether PN is necessary.

• patients with a colostomy in the descending colon may have sufficient bowel for nutrient absorption, as bowels are for reabsorbing water + salt

Ileostomy –> EN still possible if no other bowel resection, water absorption will be an issue

Jejunostomy –> PN indicated

Question 7

How much bowel is required for PN to be indicated?

Answer 7

Less than 100cm of bowel - PN indicated

100-200cm - hydration indicated, query PN, might need a little of it depending on patient

Question 8

Describe the indications for parenteral nutrition (PN) in patients with intestinal failure, including T1, T2, and T3 categories. What are the specific scenarios that would necessitate PN in each category?

Answer 8

T1 (short-term) - post-operative ileus and small intestinal obstruction

T2 (medium-term) - complex Crohn’s, fistulae, and abdominal sepsis.

T3 (long-term/irreversible) - irreversible cases like short bowel syndrome or surgical complications.

Question 9

How does the gut function impact the decision between enteral nutrition (EN) and parenteral nutrition (PN)? What factors are considered when assessing gut function for nutritional support?

Answer 9

The gut function determines whether to use EN or PN. Factors like bowel sounds, gastric aspirates, and stoma output are assessed. Bowel sounds, gastric acid secretion, stoma output volume/color are considered. If the gut works, EN is preferred.

Question 10

Define the differences between enteral nutrition (EN) and parenteral nutrition (PN) based on the study by Woodcock et al. (2001). What were the intervention groups and the key findings regarding mortality and morbidity?

Answer 10

Woodcock et al. (2001) compared EN and PN in patients with negligible intake >7 days. Mortality was higher in EN, with more morbidity. No deaths were directly attributed to PN. The study recommended PN when in doubt.

Question 11

Describe the key recommendations from the NCEPOD report (2010) regarding the use of parenteral nutrition (PN) in clinical practice. What factors should be considered when determining the route of feeding for patients?

Answer 11

NCEPOD recommends determining the feeding route based on GI function, assessed by a nutrition support team. PN is advised if EN cannot meet needs. EN and PN can be combined. Individual risks and benefits should be considered.

Question 12

How is a peripherally inserted central catheter (PICC) used in parenteral nutrition administration?

Answer 12

A PICC line is inserted at the bedside for PN suitable for central administration, providing a longer-term solution compared to peripheral access.

Question 13

Describe the differences between multi-chamber and compounded bags in parenteral nutrition.

Answer 13

Multi-chamber bags like Kabiven are licensed, stable, and ready to use but lack micronutrients. Compounded bags are unlicensed, need compounding, refrigeration, and are nutritionally complete but expensive.

Question 14

What are the components of parenteral nutrition bags and their functions?

Answer 14

Parenteral nutrition bags contain macronutrients like nitrogen for anabolic processes and carbohydrates/lipids for energy. They also include micronutrients such as trace elements and vitamins for overall nutrition.

Question 15

Explain the evolution of lipid emulsions in parenteral nutrition.

Answer 15

First-generation lipid emulsions are now rarely used due to liver concerns.

Current lipid emulsions are safer and more effective for providing essential fatty acids in parenteral nutrition.

Question 16

Describe the considerations for adjusting parenteral nutrition electrolytes.

Answer 16

When adjusting parenteral nutrition electrolytes, it is crucial to account for individual requirements, especially in cases of high intestinal losses. Regular review is necessary to ensure appropriate sodium and fluid balance, with sodium losses and high stoma output being common concerns.

Question 17

How should a compounded bag for parenteral nutrition be prepared?

Answer 17

To prepare a compounded bag for parenteral nutrition, one must calculate energy and protein requirements, determine non-nitrogen energy by subtracting nitrogen energy, decide on lipid amount (30-50% of non-nitrogen energy), meet remaining energy with glucose, add electrolytes and micronutrients, and calculate the final volume.

Question 18

Define the key steps in initiating parenteral nutrition.

Answer 18

Initiating parenteral nutrition involves conducting a thorough dietetic assessment, considering allergies and diabetes, screening for refeeding syndrome risk, ensuring suitable access, selecting a starting regimen, monitoring electrolyte levels, and assessing the need for micronutrients.

Question 19

What are the differences in micronutrient requirements between oral/enteral and parenteral nutrition?

Answer 19

Micronutrient requirements differ between oral/enteral and parenteral nutrition due to factors like deficiency risk, toxicity, stability, light protection needs, and the impact of acute phase response on plasma concentrations. Certain markers like CRP may not accurately reflect levels of selenium, zinc, copper, vitamin A/E, and ferritin.

Question 20

Describe the role of specific fat emulsions in parenteral nutrition for vegetarian patients.

Answer 20

For vegetarian patients, there are no modern emulsions available. First generation lipid emulsions like Intralipid are vegetarian/vegan but they are inflammatory

Question 21

Describe the process of determining the amount of glucose needed to meet energy requirements in parenteral nutrition.

Answer 21

To determine the amount of glucose needed, calculate 50-70% of the remaining energy requirements. For example, if 65% of non-nitrogen kcal is needed, subtract the kcal provided by other sources to find the kcal from glucose. Convert this to grams of glucose for accurate provision.

Question 22

How can glucose oxidation rate be calculated to avoid excess provision in parenteral nutrition?

Answer 22

To calculate glucose oxidation rate, multiply 4-7mg by the patient’s weight in kg by 60 minutes, then by 24 hours, and divide by 1000 to get grams of glucose needed. This helps prevent excess glucose provision.

Question 23

Define the key role of electrolytes and micronutrients in parenteral nutrition.

Answer 23

Electrolytes and micronutrients are essential additions to parenteral nutrition to replace losses, maintain biochemistry, and prevent deficiencies. Products like Addaven and Cernevit are commonly used to provide these vital components.

Question 24

What are the metabolic complications associated with parenteral nutrition?

Answer 24

Metabolic complications of parenteral nutrition include hypoglycemia and weight loss from glucose, hair loss and dermatitis from essential fatty acids, poor wound healing and muscle mass loss from nitrogen, and various deficiencies like zinc, selenium, copper, chromium, and vitamins.

Question 25

Describe the causes of abnormal liver function tests (LFTs) in the context of parenteral nutrition.

Answer 25

Abnormal LFTs in parenteral nutrition can be caused by factors like medications, sepsis, acute kidney injury/chronic kidney disease, pre-existing liver disease, underlying diseases, gallstones, and periods of nil by mouth. Short-term PN use is unlikely to be the sole cause of deranged LFTs.

Question 26

What are the considerations for weaning off parenteral nutrition in patients?

Answer 26

Weaning off parenteral nutrition should be planned and stepwise, with daily reviews of progress. Options include reducing the rate, transitioning to EN or ONS, giving 50% of the PN bag, or having days off if not fluid dependent. It is crucial to avoid supplementing inadequate oral intake with PN.

Question 27

Define the best practices for managing parenteral nutrition to prevent complications.

Answer 27

Best practices for managing parenteral nutrition include using Aseptic Non-Touch Technique (ANTT), avoiding disconnecting and reconnecting bags, planning weaning carefully, monitoring closely to prevent complications, and ensuring the dietitian plays a key role in the multidisciplinary team.

Question 28

Describe the potential risks and benefits associated with long-term parenteral nutrition (PN)

Answer 28

Long-term PN is usually lifelong and can lead to low quality of life, increased risk of infections, and abnormal liver function. However, it can be life-saving for patients unable to achieve sufficient oral/enteral nutrition.

Question 29

What are the key considerations for patients undergoing intestinal transplant surgery?

Answer 29

Patients undergoing intestinal transplant surgery may experience improved quality of life but are at risk of rejection. Close monitoring and a multidisciplinary team approach are crucial for optimal outcomes.

Question 30

Define the role of dietitians in managing patients on parenteral nutrition

Answer 30

Dietitians play a crucial role in managing patients on PN by ensuring appropriate nutrition support, monitoring for complications, and optimizing patient outcomes through dietary interventions and support.

Question 31

What can we do to manage deranged LFTs?

Answer 31

• Avoid overfeeding –> review requirements/don’t overfeed
• Optimise pareteral lipid –> change fats to antiinflammatory ones/if T2/T3 IF don’t provide more than 1g/kg/d lipis/consider lipid free days

Oral intake - maximise oral intake/reduce PN

Cyclical PN –> increase PN rate to provide 4/12 hr break