The first number is "difficulty with breastfeeding or inadequate oral fluid intake (less than 75% of usual volume)" (1) which is listed as an indicator that the baby may need referral to secondary care. Two pages later a similar but slightly different description of what inadequate feeding looks like is used: "difficulty with breastfeeding or inadequate oral fluid intake (50- 75% of usual volume, taking account of risk factors and using clinical judgement)" (2)
Unsurprisingly, the fact that these numbers are rather tidy and there is a little uncertainty expressed is due the the fact that they are based on expert opinion. Fair enough but my question is, are we measuring the right thing?
There are lots of variables in the mix here. Firstly, in breast fed babies, we have to guess what is going in. As well as what is going in, there is the issue of what comes straight back out. Finally, what is being used up in terms of calories and water depends on the work of breathing and other factors such as pyrexia. It will also probably be affected by the amount of subcutaneous fat and renal function. What is going in is only part of the equation and the formula looks much more like algebra than simple maths to me. So, why don't we cheat and look at the answers?
The answers that I like to look at are energy levels and hydration. Assessing a baby's energy levels will be easy in most cases. If a baby is alert and smiling, it is probably safe to assume that a good supply of calories and water is reaching the most frivolous part of the baby's brain. If that is the case, then the baby's carbohydrate economy is buoyant. If this is not the case then something is wrong and whether inadequate feeding is an issue or not, a subdued or tired looking baby with bronchiolitis should be referred.
Assessing hydration is done the old fashioned way as well. I look for wet mucous membranes in the mouth, good skin hydration, and wet nappies. If I am really lucky I might have a weight from a couple of days ago to compare to.
The overall appearance, wellness and alertness of the child are always going to be a more valid assessment than comparing an uncertain number (how much we think the baby is getting) to a made up number (how much we think the baby needs). So, once again, a victory for old school paediatrics and an adage which should never get old: "Look at the child."
Disclaimer: If none of this makes sense, the NICE bronchiolitis guidelines are actually very good in my opinion.
- Page 16, Full guideline NG9 Bronchiolitis in Children, NICE
- Page 18, Full guideline NG9 Bronchiolitis in Children, NICE