Following severe trauma a 35 year old woman is being enterally fed via a nasogastric tube. The dietitian  calculates  that  only 25% of  her  daily nutritional  requirements  are  being achieved. Outline your approach to this problem.

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College Answer

Again, a sensible practical approach was expected. There may be a place for early jejunal feeding or, if laparotomy is performed, insertion of percutaneous enterostomy.

Otherwise a more conservative approach involves thorough assessment of history, recent events, combined  with  physical  examination  and  perhaps  some  simple  investigations  to  address  the problem.

Are the dietitians calculations appropriate?

Why are the feeds not meeting targets? Large aspirates, inappropriate orders, starving for procedures. If it is because the feeds are not being absorbed, is this due to GIT pathology, systemic illness or narcotic infusion?

Physical examination should be performed looking for distension, rebound tenderness and presence of bowel sounds.

AXR for position of NG tube, ileus.

Treatment will be aimed at reversible causes. If there is no sign of abdominal pathology, the NG tube is in good position, orders are being followed then prokinetics should be tried and if unsuccessful recourse to naso-enteral tube is next step.

Discussion

This nebulous question does not specify why the nutritonal goals are not being met.

The question may  be approached in the following fashion:

Causes for Failure of Nutritional Support
Problem Cause Solution
The calculated energy requirement was wrong The predictive equation was inaccurate -  for example, the patient belongs to a special population - severe burns, multi-trauma, hypothermia, etc.
Or, the dietitian assessing the intake is wrong because of some basic misunderstanding.
Recalculate the goal rate using a more accurate method, eg. indrect calorimetry. Discuss basic mathematics with the dietitian.
There are numerous interruptions to feeding,
but feeds are well tolerated
Frequent trips to the operating theatre or CT scanner Either rationalise the travel time, or continue feeding during the transfers.
Alternatively, increase the rate of feeds to contribute 100% of nutritional needs in a decreased timeframe
Frequent interruptions of NG feeds due to high gastric aspirates Ensure some of the aspirated gastric residual volume is returned.
Instruct staff not to stop feeds unless the residual volume is in excess of 500ml
There is genuine feed intolerance There could be numerous reasons; among them:
-  "chemical ileus " (eg. due to opiates)
- poor gut perfusion, eg. shock
- poor gastric emptying due to ANS dysfunction
- post-operative gut damage
-

- Adjust the patient's posture to semi-upright
- Advance the NGT into a post-pyloric position
- Administer prokinetics:
   - metoclopramide or domperidone
   - erythromycin
   - oral naloxone
   - neostigmine

- Consider a PEG or jejunostomy tube

If all else fails, contribute the additional calories via TPN (after trying for up to 7 days)

The feeds are well tolerated, in terms of gastric aspirates being low,  but the nutrients are poorly absorbed The gut is ischaemic, or the villi are denuded, or there is no enough gut (short gut), or the gut transit is too fast (eg. the diarrhoea is very severe). Antimotility agents (eg. loperamide) may be required for the fast transit; otherwise, one has little recourse other than to rely on TPN.