Feeding (enteral and parenteral)

Question 1

Define enteral feeding.

Answer 1

Delivery of a nutritionally complete feed, containing protein, carbohydrate, fat, water, minerals and vitamins, directly into the stomach, duodenum or jejunum.

This term is most often used to mean tube feeding.

Question 2

What are the types of enteral feeding tubes? (6)

Answer 2

1. NG tubes - nose to stomach
2. Orogastric tube - mouth to stomach
3. Nasoenteric tube (i.e. nasojejunal and nasoduodenal) - nose to intestines
4. Oroenteric - mouth to intestine
5. Gastrostomy tube (e.g. PEG, PRG, button tubes) - skin to stomach
6. Jejunostomy tube (e.g. PEJ and PRJ) - skin to intestine

Question 3

What are the indications for enteral feeding?

Answer 3

Malnourishment or risk of, weight loss and serious health issues eg. :

• stroke - impaired ability to swallow
• cancer - fatigue, nausea and vomiting
• critically ill/postoperative patients
• failure to thrive/inability to eat in children
• conditions with increased caloric requirement - e.g. cystic fibrosis
• neurological disorders - increased caloric requirement and difficulty eating
• GI dysfunction

Question 4

What do enteral feeding solutions contain?

Answer 4

Standard feeds - contain all carb, protein, fat, water, elecrolytes and micronutrients (vitamins and trace elementes) and fibre required for a stable diet.

Pre-digested feeds - contain nitrogen as short peptides or free AAs to improve absorption in pancreatic insufficiency/IBD. Fibre content is variable and sometimes contains Vit K.

Question 5

What are the complications/risks of enteral feeding tubes?

Answer 5

• Re-feeding syndrome - in previously malnourished patients on high carb feeds –> dangerous electrolyte imbalances
• Aspiration - food into lungs. Must check tube before each feed to ensure pH <5.5
• Infection of tube or insertion site
• Nausea and vomiting - if feeds are too large/fast
• Skin irritation
• Diarrhoea - from liquid diet
• Tube dislodgement
• Tube blockage - if not flushed properly

There are not typically long-term complications of enteral feeding.

Question 6

What is re-feeding syndrome?

Answer 6

• occurs in previously malnourished patients who are fed with high carbohydrate loads
• Carbohydrates cause a large increase in circulating insulin level → rapid fall in phosphate, potassium and magnesium → increasing ECF volume.
• As tissues switch from catabolic (starvation) to using exogenous fuel, there is increase in O2 consumption, increased resp and cardiac workload → may cause tachypnoea and precipitate acute heart failure
• Demand for nutrients might outstrip supply → multiple organ failure, resp/cardiac failure, arrhythmias, rhabdomyolysis, seizure, coma, red cell and or leukocyte dysfunction.
• There may also be nausea and diarrhoea - gut may have undergone atrophy with starvation and return of enteral feeing → intolerance to feed.

Question 7

What is parenteral feeding?

Answer 7

Method of getting nutrition into your body through your veins.

Depending on which vein is used, this procedure is often referred to as either total parenteral nutrition (TPN) or peripheral parenteral nutrition (PPN)

Question 8

What are the indications for parenteral feeding?

Answer 8

For patients who cannot get core nutrients from food or have GI tract dysfunction:

• Crohn’s disease
• cancer
• Short bowel syndrome
• Ischaemic bowel disease

Enteral feeding should be used when poossible.

Question 9

Where is access for parenteral feeding?

Answer 9

Central - catheters tunnelled into subclavian vein. Central access allows delivery of more concentrated formulations into high-flow vessels but parenteral nutrition solution is thrombogenic and an irritant to veins - used for TPN

Peripheral - administered through peripherally inserted central catheters (PICCs) or standard cannullae. Tolerance to peripheral lines is increased with feeds of low osmolality and neutral pH - used for PNN

Question 10

What are the complications/risks of parenteral feeding?

Answer 10

• Re-feeding syndrome
• Catheter-related - pneumopthorax, arrhythmias, thrombosis, pleural or pericardial effusions.
• Infection - in 1-26% mostly staph or enterococcal species.
• Liver and gallbladder dysfunction - mild cholestasis with elevation of transaminases and AlkPhos
• Hyperglycaemia - in 30% so should be monitored

Question 11

What does the parenteral feeding solution contain?

Answer 11

• Iso-osmotic lipid emulsions to provide a lot of energy and reduce vein irritation, prevent hyperglycaemia and hyperosmolar dehydration
• Usually comes in 3 litre bags
• Usually delivered for 10-12 hours a day at a continuous flow rate
• Some vitamins are infused but B12 must be prescribed