Saturday, 14 November 2015

When it walks like a duck- Do I give salbutamol to this 11 month old?

This year saw the arrival of the NICE Bronchiolitis guidelines.  Like many guidelines, this requires the clinician to know that the problem that the child has is bronchiolitis. The trouble is that there are times when there is uncertainty.  It is an important distinction to make since bronchiolitis is best left well alone.  You should not prescribe inhalers, antibiotics or steroids.  Viral wheeze on the other hand requires the liberal use of inhalers for appropriate to the severity of the exacerbation.

As a medical student I was taught that beta-agonists such as salbutamol don't tend to work under the age of one.  That is only partly true.  Beta-agonists don't work for bronchiolitis and most children under 12 months with wheeze have bronchiolitis.  However when the problem is a viral induced wheeze the inhaled Beta agonist is exactly what is needed even if they child is below a year old.

Bronchiolitis and viral induced wheeze have a similar presentation but very different mechanisms which is why one responds and the other doesn't.  Bronchiolitis is essentially a problem of wetness.  The viral lower respiratory tract infection causes the airways to be constricted by the accumulation of secretions.  With viral induced wheeze, the infection has induced bronchospasm.

In both cases there will be a cough, coryza, wheeze and possibly some respiratory distress.  Only one needs inhalers or nebulisers to be given.  So how do I tell them apart?

The easiest way is to look at the child's age.  There seems to be a fairly good split between the typical age groups of the two conditions.  Bronchiolitis tends to affect those under 12 months old while viral induced wheeze tend to be seen in the over 12 month olds.  Using that as a cut off will leave you being correct a lot of the time.  Of course there are exceptions and they will usually be those children a few weeks or a couple of months either side of that cut off.

So for those who are well before their first birthday you can assume they have bronchiolitis.  If the child has already started to outgrow the clothes that they were given for their first birthday, you can assume they have a viral induced wheeze.  But what about the ones who are too close to call?

One thing that helps is the prodrome.  Typically, children with bronchiolitis have a few days of being snotty before the cough develops.  Then there is a daily worsening of cough followed by feeding difficulties.  By day 3 of the cough there may be fast breathing and an audible wheeze.

With viral induced wheeze there is a variable length of coryzal illness from a day to a week.  What is noticeably different is the onset of the wheeze and respiratory distress.  This will usually happen over the space of hours, not days.


The other factor that helps is the severity of the symptoms.  Consider our 11 month old with wheeze: If bronchiolitis affects children from birth to about 15 months of age, the most severely affected will be the littlest babies.  Wet lungs when you are a few weeks old is no walk in the park.  So by the time you are 11 months old, bronchiolitis is less likely to be severe.

Why not just try inhalers with all wheezers?  The answer is that it is possible that this might make the child worse.

If an infant has bronchiolitis, they fight the good fight against wet lungs.  They succeed against the odds since they are less able too feed and use more energy in the effort of breathing.  What we must do as clinicians is avoid making this worse.  Don't give unnecessary antibiotics that will fill and irritate their stomachs.  Don't send them home with ineffective inhalers which will result in a routine of upsetting and tiring out the child.

Conversely, make sure that children with viral induced wheeze get enough beta-agonist.  This might be quite a lot (the salbutamol paradox).

So, because it is an important distinction, use age, then prodrome and then severity in that order to decide if it is bronchiolitis or viral induced wheeze.

Edward Snelson
@sailordoctor




4 comments:

  1. Great post Edward - great fan of trajectory of illness (http://rolobotrambles.com/1555) and I think there are differences between bronchiolitis and viral wheeze in this regard.

    I would add the importance of good background history -
    i) Have they had bronchiolitis before? Recurrent 'bronchiolitis" is usually recurrent viral wheeze. Unpick the terms parents and other health care professionals use. The term wheezy bronchitis is commonly used but is not technically an official medical condition
    ii) Is there a family history of atopy. A child presenting at 10 months who has had eczema in the early months of laugh and has parents with with hay fever and asthma is far more likely to have viral wheeze than bronchiolitis
    iii) Use this as an opportunity for health promotion. It is not just appropriate to ask whether parents smoke, however uncomfortable it might be, they need to be informed of the excess severity that might/is being cause by them.

    Great work on the GPPaedTips so far!

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  2. Another point I would add is that a significant or persistent oxygen requirement tends to argue against viral wheeze in my experience, unless they are really tight. Most children with viral wheeze tend to be in air after appropriate bronchodilation.

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  3. The key to much of this is that IF you chose to try an child with an inhaler its IMPERATIVE that you go back and examine again to see if it has made a difference... if it hasn't why would you continue to flog a dead horse? We also need to ensure parents know how to give the inhaler using a spacer (assume nothing!) and that they go home with a written wheeze plan.
    I also put my hand up and happily admit that in a borderline child with bronchiolitis I will try atrovent to see if it improves the clinical presentation enough to allow parentally percieved better feeding etc. I know there is no evidence... but I've seen it work too many times not to consider it ;-)
    I will wait for the lightening bolts to strike me down now!

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  4. Thanks for all your comments. Previous episodes and response to bronchodilators (if they have been tried) are also part of my decision making. I think that the thing to avoid is the trap of always using a trial of bronchodilator as a quasi-test for viral wheeze. Placebo this may be...

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