Gastroenterology training and education

What are the indications of enteral tube feeding?

NICE 2006

• Unconscious patient
• Neuromuscular swallowing disorder- Post CVA, MS, MND, Parkinson’s disease
• Upper GI obstruction- oesophageal stricture or tumour
• GI dysfunction or Malabsorption- dysmotility, IBD, short bowel (PN may be needed)
• Physiological anorexia- cancer, sepsis, liver disease, HIV
• Increased nutritional requirements- cystic fibrosis, burns
• Psychological problems- severe depression or anorexia nervosa
• Mental health- patients with dementia

What are the routes of access for enteral tube feeding?

• Nasogastric tubes are used most commonly for short term feeding (< 4 weeks)
• Consider gastrostomy or jejunostomy feeding if the patient is likely to need long term (4 weeks or more) ETF.
• Post pyloric feeding can be achieved by endoscopically placed NJ tube or surgical jejunostomy (by laparoscopy or mini lap)

Discuss post pyloric feeding?

Post pyloric feeding is indicated when the digestive tract functions normally, but the patients cannot meet their nutritional requirements due to a passage problem at the gastric level. It also has the advantage of reducing the risk of pulmonary aspiration of the gastric contents.  The indications for post pyloric feeding are:

• Gastric outlet obstruction
• Gastroparesis or gastric food intolerance- National guidelines by Society of Critical Care Medicine and the ASPEN do not recommend holding gastric tube feeding unless the gastric residual volume is greater than 500 ml.  This rule has markedly reduced the number of patients diagnosed with gastric feeding intolerance. Prokinetic agents should be prescribed to patients who exhibit gastric feeding intolerance prior to consideration of an alternative feeding route (jejunal or parenteral nutrition).
• Known severe reflux and aspiration of gastric contents- It is important to define whether episodes of aspiration are truly caused by GORD or are the result of disorders in swallowing. It is important to understand that post pyloric feeding does not completely abolish the risk of aspiration. (risk is 2.4% Gutierrez GD et al. Radiology 1991;178:759-762)
• Intolerance of oral feeding due to passage disorder due to swelling or outside pressure onto the duodenum (pancreatitis or tumour).  Gastric feeding should be tried first in pancreatitis and if not tolerated, jejunal feeding should be considered. Jejunal feeding has the advantage of not only bypassing the passage problem but also avoids pancreatic stimulation (and thus provides rest to pancreas).
• Proximal (duodenum and first part jejunum) enteric fistula.

Discuss post pyloric feeding in critical care settings?

Many intensivists worry that gastric feeding predisposes to aspiration and pneumonia and thus prefer to feed critically ill patients via the post-pyloric route, believing that it reduces the incidence of pneumonia. However, post-pyloric feeding has no clinical advantages over gastric feeding in most critically ill medical, neurosurgical and trauma patients unless gastric feeding intolerance is present.
A meta-analysis showed no difference between gastric and small intestinal feedings with regard to the incidence of pneumonia, length of stay or mortality in a mixed group of critically ill medical, neurosurgical, and trauma patients (Marik PE et al. Gastric versus post-pyloric feeding: a systematic review. Critical Care 2003, 7:R46-R51doi:10.1186/cc2190)

If jejunal feeding is needed, are there any real clinical outcome differences between placing a PEG with J tube extension or placing a direct-PEJ (DPEJ)?

PEG/J tubes are easier to place than DPEJ tubes, however, the J-tube extension of the PEG/J system has a significantly higher rate of dysfunction (clogging, kinking, migration), leading to a higher rate of endoscopic re-interventions and interruptions in feeding.

When do you initiate feeding after placement of an enteral access device?

Traditional surgery dogma was that post-operative feedings should wait until there was evidence that bowel function had returned as evidenced by flatus or a bowel movement. This has been challenged in recent literature. So ASPEN 2009 recommends;

• Enteral feedings should be started postoperatively in surgical patients without waiting for flatus or a bowel movement. The current literature indicates that these feedings can be initiated within 24-48 hours.
• A PEG tube may be utilized for feedings within several hours of placement: current literature supports within 2 hours in adults and 6 hours in infants and children.

How much feeds need to be given?
See the module “Estimating calorie requirements”
If no advice is available 25ml/kg/day of standard 1 Kcal/ml feed is often appropriate.

Discuss initiation and advancement of an enteral nutrition regimen?
There are limit data to form strong recommendations for the best starting administration rate for initiation of enteral feeding. Stable patients tolerate a fairly rapid progression of EN, generally reaching the established goal within 24-48 hours of initiation.
In practice, formulas are frequently initiated at full strength at 10-40 mL/h and advanced to the goal rate in increments of 10-20 mL/h every 8-12 hours as tolerated.

What are the modes of ETF?

Type		Advantage	Disadvantage
Bolus feeding	Administration of 200-400ml of feed over 15 minutes at regular intervals	Avoid it	Cause bloating & diarrhoea, bolus delivery in jejunum can cause dumping type syndrome
Intermittent feeding	Breaks in feeding of 6 hours or more are used (promotes antibacterial conditions in the gut)	Continuous feeds should be changed to intermittent feeds asap
Continuous feeding	Feed delivered continuously over 16-24 hrs. NJ feeding necessitates continuous feeding due to loss of the gastric reservoir	i. Commonly used for very ill patients (ICU). ii. Safer and more practical if insulin administration is needed	i. Continuous infusion leads to higher intragastric pH and can promote bacterial growth ii. Should not be given overnight in pts at risk of aspiration

What are the types of enteral feed formulae?

The choice of feed to be given via ETF is influenced by a patient’s nutritional requirements, any abnormality of gastrointestinal absorption, motility, or diarrhoeal loss, and the presence of other system abnormality, such as renal or liver failure.

Most commercial feeds contain 1.0 kcal/ml, with higher energy versions containing 1.5 kcal/ml. They are generally available in fibre free and fibre enriched forms.
They are nutritionally complete. The following feeds are generally used.

• Whole protein (polymeric) feeds- These contain nitrogen as whole protein.
• The carbohydrate source is partially hydrolysed starch and the fat contains long chain triglycerides (LCTs).
• Elemental/peptide feeds- These feeds contain nitrogen as either short peptides or, in the case of elemental diets, as free amino acids. The aim of ‘‘predigested diets’’ is to improve nutrient absorption in the presence of significant malabsorption. Their importance is probably greater in maldigestive (for example, pancreatic disease) rather than malabsorptive states, and in patients with a short gut and no colon their high osmolality can cause excess movement of water into the gut and hence higher stomal losses
• Disease specific and pharmaco nutrient feeds- Renal feeds- Contain reduced amounts of sodium, potassium and phosphate.   Liver patients need low sodium low volume feeds.

Which formula should be used in non stressed diabetic patients?

American Diabetes Association and European Association for the Study of Diabetes recommend that 60–70% of energy be divided between carbohydrates and monounsaturated fat (MUFA), with less than 10% from polyunsaturated fat, less than 10% from saturated fat and less than 15% from protein. Simple carbohydrates can be included but should constitute less than 10% of total energy. Most diabetes-specific enteral formulae comply with this rule.

Which formula should be used for blood glucose control in ICU-patients?

In the ICU setting where strict glycaemic control with the use of exogenous insulin is achieved relatively easily when standard or ICU-specific formulae are used, there is no reason to believe that any specific formulae would be required.

How to monitor enteral feeding?

• Early monitoring requires blood glucose to be checked at 4–6 hour intervals and plasma sodium, potassium, magnesium, and phosphate to be checked daily especially those at risk of refeeding syndrome
• LFTs and full blood counts must be repeated weekly until the patient is stable.
• Body weight should be measured weekly
• Trace element (Zn, copper, selenium) and vitamin levels (B12, folate, Vit D) should be measured on commencing ETF if possible. Patients on long term feeding should have periodic checks of vitamin and trace element status.

What are the complications of ETF?

Complications are diarrhoea and aspiration.

• Diarrhoea-
  • ETF related diarrhoea occurs in 30% of enterally fed patients on the ward and 60% of patients on ICU.
  • Parenteral nutrition may be required if elimination of all other causes of GI upset and/or administration of simple symptomatic treatments fails to resolve the problem.
  • Likely causes of ETF diarrhoea
    • Feed related
      • Bolus feeding
      • Continuous feeding at high rate
      • Feed temperature (cold)
      • The evidence for any of these leading to diarrhoea is minimal. It is unlikely that enteral feeds causes ETF related diarrhoea but a lack of cephalic response in ETF feeding is significant in the pathogenesis of ETF diarrhoea.
    • Non Feed related
      • Drugs- Antibiotics (commonest cause), laxatives, Mg antacids, Drugs containing active fillers like sorbitol
      • Infections- C diff and other
      • Lactase deficiency (primary or secondary) – limit milk if the pt is also taking food orally
      • Fat malabsorption in those with pancreatic deficiency, biliary obstruction or extensive ileal resection
      • Hypoalbuminaemia- considerable debate whether it can cause diarrhoea through intestinal edema. Unlikely as pts with nephrotic syndrome or cirrhosis do not have diarrhoea.

Discuss the treatment of ETF diarrhoea?

• Treat any predisposing conditions as above.
• Standard feeds contain little or no fibre. Use fibre enriched forms of enteral feed. Ingestion of fibre slow intestinal transit time plus fermentable polysaccharides stimulates colonic bacterial population and hence stool mass. However fibre rich diet does not often help ETF diarrhoea
• Use loperamide/codeine on a symptomatic basis
• Anecdotal reports of usefulness of probiotics

What are the precautions needed during enteral feeding to reduce the risk of aspiration?

• Patient positioning- ASPEN 2009 recommends
  • Elevate the backrest to a minimum of 30º, and preferably to 45º, for all patients receiving EN unless a medical contraindication exists.
  • Use the reverse Trendelenberg position to elevate the head of bed (HOB), unless contraindicated, when the patient cannot tolerate a backrest elevated position.
  • Feeding can be continued during short periods of time when it is necessary to lower the HOB for a procedure or a medical contraindication.
• Monitor gastric residue volume (GRV) – Measurement of GRV is one technique used to prevent aspiration. ASPEN 2009 recommends
  • Check gastric residuals every 4 hours during the first 48 hours for gastrically fed patients. After enteral feeding goal rate is achieved, GRV monitoring may be decreased to every 6-8 hours in noncritically ill patients. However, every-4- hour measurements are prudent in critically ill patients.
  • If the GRV is > 250 mL after a second gastric residual check, a promotility agent should be considered in adult patients.
  • A GRV >500 mL should result in holding EN and reassessing patient tolerance by use of an established algorithm including physical assessment, GI assessment, evaluation of glycemic control, minimization of sedation, and consideration of promotility agent use, if not already prescribed.
  • Consideration of a feeding tube placed below the ligament of Treitz when GRVs are consistently measured at > 500 mL.

Ref

1. Bankhead R et al. Enteral Nutrition Practice Recommendations. JPEN J Parenter Enteral Nutr. 2009 Jan 27.