Fluid management in dehydration

Before we go into the management of dehydration in a little more detail, it is important to remember that a mild to moderate degree of dehydration is common in children who are ill and does not always require medical intervention. Let’s recap what we have talked about before: the common reasons that children might become dehydrated.

Most causes of dehydration will fit into one of the following 3 categories:
1. Inadequate fluid intake (gingivostomatitis, tonsillitis)
2. Increased fluid loss (gastroenteritis, DKA)
3. Increased insensible losses (fever)

So the only way you will find out which of these categories a patient fits is with a good history of the events leading up to the child’s presentation to the emergency services, and a thorough examination. Whilst the history is really important, it can sometimes be hard to get an accurate story about things like fluid intake, wet nappies, number of wees, vomits and poos. It is not uncommon in the emergency department to go to see a child who has apparently not passed urine for 24 hours and has drunk very little, to be faced with a smiling, drooling, happy baby sticking Wotsits up their nose.

Now the parent is not lying when they report that the child has not had a wee, but when you dig into the history what they mean is that they have not had what they would consider to be a normal wee. And likewise when they say the child has not drunk anything, they will often mean that they haven’t drunk their normal milk and not really count the water that the child has been sipping on. Now clearly some children will not have drunk much in the preceding 24 hours and will be a little dry, so the next thing to do is to try to estimate the degree of dehydration (quoted as percentage dehydrated where the percent refers to the percentage loss of total body water). The following is a good enough guide:

Percentage dehydrated:
<5% Mild – May have no signs except dry lips
5-10% Moderate – Reduced urine output, dry mouth, sunken fontanelle
>10% Severe – As above plus sunken eyes, altered skin turgor, cardiovascular changes

In reality you will rarely see a child above 10% dehydrated in the developed world (maybe the odd very severe DKA or some rare inherited diarrhoeal illness with massive fluid losses). If you do, these children will be desperately sick. So most children will fall into the mild to moderate group and what you do will depend a little on the cause. In a child with herpes gingivostomatitis (a relatively common condition associated with the development of painful ulcers inside the mouth) or proper pus-covered tonsils in a nasty tonsillitis, the thing often stopping them from drinking is pain. So the first thing to do is to try to assess this. Make sure that they have had at least basic paracetamol or ibuprofen. In hospital we would often escalate pain relief in these children to include opiates and the results on their fluid intake can be dramatic.

You can also try local anaesthetic sprays (Difflam is an example) but I would describe these as a Marmite drug; people either think they are fabulous or a waste of time. Certainly in younger children they can be difficult to administer, but may have a useful role in older children who can self-medicate.

So in this situation you can give something that may help the symptoms and encourage the child to drink. This is not the case with some of the other causes (although we do sometimes give anti-sickness drugs in the ED). Most children with mild to moderate dehydration should be rehydrated via the gut with oral fluids rather than IV. Sometimes (particularly with small children) we may need to use a nasogastric tube but this is still generally preferable to IV fluids.

Getting a child who is feeling unwell to drink can take patience and perseverance but in my experience the best way to do it is to give them easy access to drinks that they like. Things like oral rehydration solutions are great but many children do not like the taste, so opt for something that they will drink. If they are able to take what they want, when they want it, most children will drink enough to avoid coming into hospital. In children who are reluctant to drink, ice pops or ice lollies are a great alternative; children like them, they will ‘drink’ them slowly and will be less likely to vomit them back. Many emergency departments stock ice pops for this very reason; the biggest problem is stopping the staff eating them! Remember, we’re not trying to get kids back to a completely normal state of hydration, rather make sure that they are having enough to stop them from deteriorating keep them in the mild group until nature takes its course and the illness settles.

In some cases, we will be too far behind, or the symptoms will be too florid for oral fluid to be adequate and in this case, IV fluid will be needed. The classic case that fits this is the child with DKA. Unless the child is actually shocked, there is rarely a need to give fluid boluses and, if the blood sugar is normal, a safe initial fluid would be 0.9% saline. Clearly if the BM is low, this will need to be addressed.

Maintenance IV fluid for a child would be calculated based on weight as follows:
4 ml/kg/hr for first 10kg
2 ml/kg/hr for next 10kg
1 ml/kg/hr for subsequent kg

So a 26 KG child would require (10×4) +(10×2) +(6×1) =66ml/hour of maintenance IV fluid.

In summary, the majority of children who present to emergency departments with dehydration are on the mild to moderate end of the spectrum and should be able to be maintained with oral fluids (hopefully at home). Parents need to be given clear information about what signs to look for to suggest a deterioration in their child and the need to seek further medical attention.