Saturday, 18 July 2015

Do I have to? (measuring oxygen saturation in bronchiolitis)

When something tells you what you already know...

I was recently contacted by a GP who wanted to know which oxygen saturation probes we use for babies in the Emergency Department where I work.  They were being proactive and trying to equip themselves to meet all the recommendations of the NICE Bronchiolitis guidelines.

[It is worth mentioning here that the understanding of the term bronchiolitis varies around the world.  In this context, it refers to a viral lower respiratory tract infection (in a child usually under the age of 12 months old) which has caused inflammation and secretory mucous plugging in the airways.  Typical features are cough, coryza, wheeze and difficulty feeding.  Bronchiolitis does not respond to inhalers or other medication.]

When I read the guideline, I was struck by a couple of things.  The first is the idea that the child with bronchiolitis would have to look seriously unwell to a General Practitioner before they decided to refer.  Now I know that unwell is a subjective term but my experience is that the vast majority of GPs have an excellent antenna for what I would call an unwell child.  If a child with bronchiolitis looks ‘seriously unwell’ and is in a GP surgery they may well need an emergency ambulance.  I think that the wording in the guideline is probably trying to recognise the fact that a child with bronchiolitis is not technically well.  The may not be well but they should look well.  If not, I would refer.

The next thing that struck me was the issue of persistently low oxygen saturations as a decider for a referral.  Measuring O2 saturations in General Practice is going to be a real challenge.  Most GPs will not have access to suitable probes.  Even if available it is often difficult to get a meaningful reading, especially when a child is snotty and angry.

Now don’t get me wrong, O2 saturations are very important in bronchiolitis.  I use them all the time to decide whether the child should have supplemental oxygen.  It seems like a good way to decide that.  As a doctor in a hospital, when I see a child with bronchiolitis I only really have four questions:
  • Does this child have uncomplicated bronchiolitis?
  • Does this child need feeding support?
  • Does this child need supplemental oxygen?
  • Does this child need resuscitation or critical care?

Back to the GP surgery, the real question is, will a baby with bronchiolitis who persistently has O2 saturations of 91% and below have none of the other features that trigger a referral for hospital inpatient assessment?  In all honesty (and as you can imagine, I am pretty keen not to make myself a target here) I think not.  I have no grade A evidence to back this up so instead I have a factual statement and an opinion:

Another question is: what is of most value in a primary care assessment of a baby with bronchiolitis?  Time is limited and best spent on identifying the features that identify the front of the problem not the back.  If respiratory distress, poor feeding and looking unwell are present before sats drop consistently, then ask those questions first.  Also ask whether this is another condition such as a cardiac defect masquerading as bronchiolitis.

With regards to the second question, I have asked a few people what they do if they can’t get a sats reading and the answer tends to be the same: look at the child.  When it comes to oxygen saturation, even in some quite acute situations it is additional rather than mandatory information.  A blue child is a blue child.  The O2 saturations are a useful number but I am not going to stand there for five minutes trying to get the probe to read properly before I do something about it.

What about the guidelines though?  We all have to follow guideline don’t we?  Of course you do.  If you have measured the sats and they are persistently below 92% in air, you should refer the child.  This assumes that the child did not otherwise need referral  and you still chose to measure sats.  The NICE guideline does not require you to measure saturations in bronchiolitis, it only requires you to act on the number if you have measured it.

Edward Snelson
Member of a society so secret even I can't remember what it is

Disclaimer: My experience is not transferable as I use a medical tricorder to measure oxygen saturations

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