Wednesday, 23 November 2016

Empirical Paediatrics – What is the best rehydration fluid for children with gastroenteritis?

When children have an uncomplicated gastroenteritis, dehydration is the enemy.  There are lots of things that we can give children to drink, but what is the best rehydration fluid to keep children out of hospital?

There are many things said about which fluid is best.  NICE recommends water or milk to maintainhydration but says to avoid fruit juice and carbonated drinks. (1)  In children who require rehydration they recommendoral rehydration solution (ORS).  In my previous post I listed 10 myths about gastroenteritis and used that to point out the NICE recommendations.  This advice conflicts with a study published in the JAMA (2) this year which showed that half strength apple juice was more likely to work than oral rehydration solution.

So, I’ve had another look at the basis of the NICE recommendation that we should “use ORS solution to rehydrate children” and the reason given is: “Although there were no clinical trials on the effectiveness of fluids other than ORS solution in the treatment of dehydration, the GDG considered that the composition of such fluids was generally inappropriate.  In dehydration due to gastroenteritis, both water and electrolyte replacement is essential, and non-ORS solution fluids do not usually contain appropriate constituents.  ORS solution was considered the appropriate fluid for oral rehydration.”

In other words, there was no evidence to support other fluids than ORS and there was reason to suspect that they are not ideal.  The trouble with two plus two is that it only equals four if there are no unknown variables.  The empirical approach dictates that instead of trying to figure out what should be true, we only believe what can be evidenced.  That removes the risk that there are unknown unknowns.  In the case of keeping a child hydrated, there is a big wildcard- the child.
One of the more interesting results of the apple juice vs oral rehydration fluid study was that the effect (half strength apple juice being more effective) was more pronounced in children over the age of 2 years.  I think that phenomenon is easily explained by two things:
  • Children develop the ability to choose for themselves
  • Oral rehydration fluid has a disgusting taste

When looking after children, we often have to choose between the treatment that is best on paper and the treatment that the child will take.  In this case, taste beats logic hands down.

So what do you do when your guideline tells you not to do something?  I would say that we need to recognise that while guidelines have strengths, they also have weaknesses.  NICE and other similar guidelines require a huge amount of searching through evidence, appraising applicability of the literature, and ultimately a decision to be made by people, with everything that entails.  What we get from that is a load of recommendations from people who have worked really hard to give us the best answers that they can come up with.   Now that there is evidence for apple juice, this will no doubt be considered when the guidelines are revised - a process that will take a very long time.

Even when a guideline is up to date, it is up to us to apply it to the child in front of us.  For example, where is the guideline for treating gastroenteritis in a child with autistic spectrum disorder?

Will flat cola be the next thing to be shown to be effective after all?  Who knows?!  What I do know is this: we now have an evidence base for a rehydration fluid that is palatable, readily available and doesn’t require a trip to the pharmacy or the doctor’s surgery.  That has got to be a win for de-medicalising and a victory for self-care.

What do you do if the child doesn’t like apple juice?  Don’t give them that then.  What is clear is that (within reason) the best rehydration fluid for a child is the one that they will take.

Edward Snelson
Eventual empiricist

Disclaimer - I was taught the theory of empricism by my daughter.  If this is all wrong, it's her fault.

  1. Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management, NICE CG84, Published date: April 2009
  2. Freedman, S et al, Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis, JAMA. 2016;315(18):1966-1974