Malnutritrion Flashcards
LO:
- Appetite regulation: Outline the hypothalamic circuits controlling body weight and relate these to the aetiology, complications and management of obesity and malnutrition.
Nutrition in the Critically Ill Patient
Case study: ICU - Severe Acute Pancreatitis
No medical history but social history reveals chronic alcohol consumption
Raised urea that starts to normalise due to electrolytes given, further increase in white cell count
BIPAP is non invasive ventilation
ICU medications – nutritional considerations
Medications commonly used on ICU
Lots of consequences, often slow gut motility and slow blood flow to gut risking gut ischaemia.
Some contribute calories themselves eg Propofol which need to be taken into consideration as don’t want to overfeed patients, particularly when they are critcally ill.
Many patients in ITU regardless of whether they have diabetes before admission, many develop insulin resistance and show hyperglycaemia, and so will require insulin and so need to be cautious if we are enterly feeding and the feed has to stop, we need to prevent the risk of hypoglycaemia.
Many meds give laxative effects so need to determine whether this or the feed is giving the diarrhoea.
Commonly have a PPI, and one of the main ways we check the position of the nasogastric tube before using it for feeding, is to assess the pH from the stomach. If using a PPI this will lead to a raised pH and therefore this method cannot be used to assess tube placement.
Many meds that have drug-nutrient interactions eg Phenytoin, so feed needs to stop for a few hours either side of medication.
ICU: Severe Acute Pancreatitis
Surrogate anthropometric measures as he is ventilated and so we can’t ask him his height so use ulna length to give estimate
When patients are on ITU they will have a Ryles (nasogastric) tube in situ measuring their gastric tolerance. We want to know that they can tolerate their own gastric secretions, so this is regularly measured every 4 hours.
- High risk of malabsorption so given peptide feed with a high ratio of medium chain trigylceride fat.
- If there is a one off high residual volume, doesn’t warrant action, but here we have a increasing trend.
- Start prokinetics eg metoclopramide and erythromycin, sometimes together, to try and get stomach to empty quicker. This had no benefit for this man.
=Eneteral nutrition as it is superior to parenteral as it goes straight into gut.
Gentleman is sedated and ventilated so unable to eat and drink, so want to start feeding within 24 -48 hours of admission as long as haemodynamically stable and as much as possible we should aim to use enteral approach because this
- Maintains gut integrity
- It modulates the systemic immune response
- And it attenuates disease severity
Historically meant to not feed to allow pancreas to rest but now there is robust research shows that it is detrimental to not feed into gut with pancreatitis, ‘pancreatic rest’ has no benefit.
Q2. Is patient at risk of refeeding syndrome? If so, what needs to be prescribed?
=Yes according to nice as bmi below 18.5, history of high alcohol intake, he has eaten very little for more than 5 days and also his potassium is low.
So we would prescribe iv pabrinex 30 mins before feeding. And pabrinex, among other vitamins will contain thiamine. We know that thiamine is a coenzyme in the metabolism of carbohydrate, and people can be put at severe deficiency risk if they go into refeeding syndrome and they are already deficienct in this B vitamin.
We know from patients with a high chronic alcohol intake, they can be at risk of thiamine deficiency for a number of reasons, including they will be intaking smaller doses of thiamine in their diet, but also ethanol inhibits absorption of thiamine as well.
Can be far more aggressive with nutrition than on ward as in ICU measures electrolytes continuously so can give more carbohydrate
Type 7=diarrhoea
Try to protect skin due to frequency of passing stool
Anthropometric measures suggested adequate nutritional support (grip test okay)
=Trial naso-jejunal tube (NJT) feeding
As have sternosis in duodenum so if place duodenum distal to this may still be able to feed into gut
If sternosis is too great and can’t pass NJ tube, so will have to consider parenteral nutition.
Placed in radiology and sometimes at bedside.
=Start PN, but still continue enteral feeding as want to continually challenge gut, to maintain gut integrity as much as possible as don’t use it it can become leaky and there is a high risk of bacteria translocation and we know this can exacerbate pancreatitis.
Short Bowel Syndrome (SBS)
Can range from 300-800cm in adults so definition is hard
Short Bowel Syndrome (SBS)-critical lengths
Short bowel syndrome
• 2 metres or less from duodenojejunal flexure.
Impact of bowel resection is best understood by looking at where nutrients are usually absorbed in small bowel. So looking at image on left, we find that for most nutrients, they’re absorbed within the first 100-150 cm of the jejunum. There are exceptions including B12 and bile salts, which are absorbed at the ileum. But this shows that by resecting the bowel there are nutritional consequences.
Images on right, looking at image on left and middle both have a colon unlike in a jejunostomy which ends in a stoma at the abdomen ie colon is removed.
Benefit of having colon is that it allows for the reabsorption of sodium and fluid and fatty acids. It also slows intestinal transit which is good for nutritional absorption an also it allows for intestinal readaption over a period of time. So if we don’t have that colon, we have large sodium and water losses, we have increased rates of gastric emptying, and also faster gut transit, as we’ve lost ileal and colic breaking systems.
Critical lengths show the lengths at which a patient can no longer manage with oral diet alone and requires some form of parenteral support, so whether that’s fluid, electrolytes or parenteral nutrition.
SBS: Jejunostomy Case Study
Intestinal Losses
Daily secretion from saliva, gastric and pancreas, amounts to approximately 4L arriving at the upper jejunum, and usually most of that is reabsorbed eg in colon but person with jejunostomy will have high losses.
=<1.5L/day
Immediately after surgery would see about 6L but at 6 weeks we would be aiming for 1.5L per day
Nutritional assessment
Urea is deranged, as is magnesium
Omeprazole to prevent gastric hypersecretion which is seen in early stages of bowel resections
Also on antimotility agents
=Restrict fluid intake, and want patient to drink a litre of electrolyte mix.
Oral Rehydration Solution
If reporting dehydration many try and increase oral fluid intake but for the most part they should restrict fluid intake, as drinking hypotonic fluid eg water, tea, coffee, alcohol (ie anything with a sodium content of 90mmol or less) this will result in net efflux of sodium into the bowel lumen, and with that water will move, until a concentration gradient of about 100mmol/L is reached. And this will induce a high stoma output and further dehydration and losses.
So if someone is really thirsty and they are drinking these fluids, they are essentially dragging sodium into gut lumen and having further losses.
There are also certain hypertonic fluids which have the same outcome, so these are fluids with high sorbitol or glucose content, eg things like coca cola, Fruit juices etc and because they are so concentrated, there will be a net secretion of fluid into the gut lumen, to try and dilute these concentrated fluids, and it will have the same impact of high output.
This is different from other hypertonic solutions, namely electrolyte mix or oral rehydration solution, and these are solutions with a sodium content of between 90 and 100 millimoles of sodium. This will induce greater sodium and water reasborption and reduce volume of output.
So answer is:
- Restrict oral fluids
- Restrict hypertonic fluids to a litre a day (includes hypertonic solutions such as coke and fruit juice)
- On top of this want patient to be drinking a litre of electrolyte mix
Nutrition Intervention-DIETETIC INTERVENTION: JEJUNOSTOMY (This diet differs to that prescribed for jejunocolic anastomosis i.e. presence of a colon)
Don’t absorb calories so double calories and nitrogen.
Go for lower fibre diet as anecdotally lower fibre tends to lower gut intestinal transit.
Due to malabsorption need to think about fat soluble vitamins, as well as selenium and B12.
Magnesium can be low for a number of reasons but priority would be to correct sodium before magnesium
May benefit from not eating and drinking at the same time as this helps slow intestinal transit.
=
< 20 mmol/L
Sodium value of 20 or less
Urinary sodium tends to be used alongside plasma sodium, because it can respond much quicker to dehydration.
Monitored in early stages around twice a week
Nutrition Goals
1) Prevent dehydration
2) Improve nutritional status
