Thursday, 31 December 2015

High Voltage - What the diagnosis plus severity means for management of viral wheeze


In the previous post, I concentrated on giving the correct label to the child under the age of five with recurrent episodes of wheeze.  I'd like to pretend that that makes the management simple but I just can't do that.  Not only are the diagnoses confusingly difficult to tell apart sometimes but there are overlaps with treatment options.  So are there actually distinct clinical entities at all?

There are important differences between the two main groups: viral wheeze and asthma/ multi-trigger wheeze.  Once again though, I have to emphasise that viral wheeze is not a lesser diagnosis and can cause life-threatening exacerbations.   It is possible that there are just these two entities and that the viral wheezers need different treatment at the more severe end of the spectrum.  After all, high voltage can do bad things to a circuit.


What is particularly confusing for the generalist is seeing children with a diagnosis like viral episodic wheeze being given a steroid inhaler.  You might be excused for exclaiming WTF!  (Wheeze Treatment Freestyle!)  Surely the whole point is to avoid giving steroid inhalers when the diagnosis is viral wheeze.  Well, as is often the case, yes and no.  Yes, most of the time but no, not always.


The vast majority of children who only get wheeze during a viral illness will do so relatively infrequently.  Also, the episodes in most cases will be mild or moderate and (more importantly) respond well to decent doses of bronchodilators.  The key differences between these children and the smaller number of children who have an atopic cause to their wheeze are that preventative steroid inhalers are not at all likely to prevent or blunt exacerbations of viral wheeze, and the evidence is that systemic steroids do not work for acute episodes.

However, not all viral wheezers were created equally.  Some get frequent exacerbations and some get frequent and severe exacerbations.  There is much debate about phenotypes, genotypes and other big words that don't mean much to the poor three year old who is getting the symptoms.  There is genuine uncertainty about whether there are multiple entities or overlaps and polymorphism.  My  hope is that the paediatric respiratory world find a way to identify the subgroups without over-complicating the list of possible diagnoses.

What we have at the moment is two main groups, with the more severe end of the viral wheeze group being treated in ways that look remarkably similar to the asthma group.  Similar, but not the same.

With the child under five who has an asthma pattern of wheezing, steroid preventer inhalers are a cornerstone of management.  If the diagnosis is recurrent viral wheeze, steroid inhalers are an option when exacerbations are very frequent, especially if severe.  The current advice is that a trial of steroid inhalers should be evaluated and should be stopped if not helpful.  How one knows whether the trial has worked is another question.  If anyone knows a cast iron way of deciding this please get in touch or post a comment.

Edward Snelson
@sailordoctor

Disclaimer: I am not a Respiratory Paediatrician, but sometimes I see so many children with wheeze, it feels like I should be.



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