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

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

Tuesday, 15 December 2015

How is your wheezer wired? Asthma vs Viral wheeze in the under 5 year old.

This week, I was asked a very good question by one of my colleagues in primary care: Why are children under the age of five who have recurrent wheeze and who are clearly atopic not given a diagnosis of asthma?  It's a question I have been asked many times before before, often accompanied by a frustrated and confused expression.

Are paediatricians allergic to diagnosing asthma in under five year olds?  It might seem like it.  The answer is no, but the diagnosis is avoided by most paediatricians and some have stopped using that term altogether (preferring multi-trigger wheeze for the under five year olds).  So when is it asthma?

Some children under the age of five with atopy and wheeze are asthmatic (or have multi-trigger wheeze if you like) but most are not.  Most have recurrent viral wheezing.  The difference is all in the circuitry. Remember circuit diagrams?  You may have intentionally blocked them out from your memory but for the purposes of this explanation it will be helpful, especially for the visual/ special learners, of which I am one. 

The thing is that lots of children have viral wheezing episodes and lots of children have atopy, usually in the form of eczema.  To find them both in the same child is reasonably common so association does not prove causation.  For that you need to establish whether the two things are happening in series or parallel.  This is where my circuit diagrams come in.

Fig 1. When a child has episodes of wheeze that are not related to anything other than viral illnesses, then any co-existing atopy is not thought to be part of the problem.  In these cases the diagnosis remains recurrent viral wheeze.

Fig 2. If there are episodes of wheeze that are unrelated to viral illnesses then coexisting atopy is the likely cause and these children are diagnosed with asthma.

Why does it matter what label we give this?  The main reason is that the chronic treatment is different.  In a review article in the BMJ, the evidence is summarised for treating acute episodes of viral wheeze with bronchodilators only, without either acute or prophylactic steroids.
When it comes to knowing whether your patient’s wheeze and atopy are wired in series or parallel, it all comes down to precipitants and interval symptoms.  If the precipitant is always a viral illness and there are no interval symptoms, then the wiring is in parallel (recurrent viral wheeze).  If there are episodes in the absence of viral illness, or there are interval symptoms (usually frequent cough or wheeze) then the wiring is in parallel (asthma).

Are there any drawbacks to having this separate diagnosis?  I can think of a few.  Firstly, having seen life-threatening exacerbations of viral wheeze I know that the acute episodes are just as capable as asthma attacks of becoming severe and deteriorating rapidly.  Recurrent viral wheeze is not a benign condition and children do die from it.

My next concern is whether or not these children get themselves into the system properly in primary care.  I know that with the current systems in place, children with asthma will be easily identified in a General Practice setting and thus get an annual review, inhaler technique checked and an invitation for an annual influenza vaccination.  Children with recurrent viral wheezing should probably also get these, but there is little guidance and no quality framework for recurrent viral wheezing. 

So how do we make sure that these children are managed appropriately?  The separate label of viral wheezing allows us to treat them consistently without giving treatments that are not going to help.  The same label risks putting these children on one side or implying that they are not at risk of severe episodes.
It does however make me wonder if the label of 'multi-trigger wheeze' is a step too far.  The European Respiratory Society Task Force defines a clinical entity "as a cluster of associated features that are useful in some way, such as in managing the child or understanding the mechanisms of disease."  Since the majority of these children are managed by general practitioners I would argue that the diagnosis of multi-trigger wheeze should be useful to them.  I am struggling to see a clear benefit.  Having labels that change and multiply can have a detrimental effect by confusing clinicians and parents alike.  In the pursuit of purism, we can end up with nomenclature which is more academic than practical.

So, let's stick with the terms recurrent viral wheeze and asthma for now.  That still leaves us with the need to ensure that the recurrent viral wheezers get treated as children with a debilitating and potentially dangerous respiratory problem.  So, can General Practitioners come up with solutions to this?  Part of the answer will be awareness and I hope that this little update has helped.  I suspect there is also a need for coding ingenuity.  It may be that others have recognised this conundrum and come up with novel solutions.  If so, please comment below and share your ideas.

Edward Snelson
Medical polyglot

Disclaimer: I fear change

  1. Andrew Bush, Managing wheeze in preschool children BMJ 2014; 348 
  2. Brand PL et al. Definition, assessment and treatment of wheezing disorders in preschool children: an evidence-based approach. Eur Respir J2008;32:1096-110

Thursday, 10 December 2015

Is your wheezer happy or are they waving a red flag?

Once you have decided that a child has bronchiolitis, there is only one real decision to be made*: home or hospital?  In some cases this decision will be made clear but for others the clues may be more in need of detective work.

*Decisions re antibiotics, inhalers and steroids are easy: don't give them!

If possible, babies with bronchiolitis should be kept well away from hospital.  Nothing quite makes bronchiolitis worse than catching rotavirus gastroenteritis from the nice family in the waiting room, while you are waiting for your mother to see the paediatrician who will send you home.  But, if you need to go you need to go.  There are three main categories of things that necessitate admission:
  • Inadequate feeding
  • Ineffective breathing or excessive work of breathing
  • A red flag symptom
Although they do not necessarily mandate referral, a risk factor that makes a sudden collapse more likely is the fourth factor in the referral risk assessment.

Inadequate feeding was covered in the last post.  Feel free to do the maths, work out what the baby is getting, look at the baby or all of the above.  For me, how alert and hydrated the child is will always be a better measure of adequacy.

Ineffective breathing or excessive work of breathing is based on many factors.  It is important to assess respiratory rate, intercostal recession and how loud the breath sounds are on auscultation.  I would say that it is even more important to look at the baby and get a gut feel for how they are coping.

The term "happy wheezer" has been around for as long as I can remember.  A happy wheezer is a baby with bronchiolitis who, often despite an impressively audible wheeze, looks ridiculously happy.  It's funny that none of the official guidelines legislate for the happy wheezer who is above the 91st centile for weight (catchy eh?).  I think that they deserve a pathway of their own.  They seem to cope well and manage far better than equivalent skinny babies with bronchiolitis.

There are two other considerations which affect the level of clinical concern.  These are risk factors and red flags.

Risk factors are important to ask about and will often not be volunteered unless the right questions are asked.  Risk factors in children with bronchiolitis include:
  • Ex-prematurity
  • Underlying respiratory problems e.g. chronic lung disease
  • Age under three months old
  • Underlying cardiac problem
  • Underweight
  • Known immunodeficiency
  • Neurological problems
The presence of risk factors presents an interesting conundrum.  Take the baby with mild bronchiolitis who is two months old.  They do not currently need nasogastric feeding nor do they need supplemental oxygen.  So why refer?  The argument for is that they are more difficult to assess and they will decompensate more rapidly.  The argument against is that being at risk and in hospital can actually be a bad thing.

The presence of a risk factor does not change the clinical assessment of the child (they still have mild bronchiolitis after all) but it sometimes changes the decision to refer or get advice from an experienced paediatrician.  If in doubt, discuss.

The well baby with mild bronchiolitis and a risk factor is better not sent to the emergency department for all the reasons above.  If they need to come in they should be referred directly to paediatrics.

Finally, there are red flags.  These are great because they make the decision easy.  If a child with bronchiolitis has a red flag, they must be referred for observation as a minimum.  Most will need intervention.  Red flags include:
  • Increasing pauses in breathing
  • Grunting
  • Refusing feeds
  • Head bobbing
  • Not waking for feeds
  • Floppy
  • Pale or cyanotic episodes
  • Episodes which alarm parents
Some red flags tell you what you already know - bad things are happening for this baby.  Some red flags tell you that bad things are happening even when it is not obvious from looking at the baby.

So the decision to bounce a bronchiolitic in the direction of a paediatrician is usually straightforward.  If they're need help feeding or support with breathing then the paediatricians need to have them.  Also refer if there are red flag signs or symptoms.  If they are mild but have a risk factor, then either refer or discuss them with an experienced paediatrician.

If the episode is mild and there are no risk factors or red flags, keep them well away from hospital.  They are not good places to be.

Edward Snelson

Disclaimer:  If the baby is waving an actual red flag, they are probably fine.

Friday, 4 December 2015

Enough already! Adequate Feeding in Bronchiolitis

It can be difficult to know whether a child with bronchiolitis is best managed in the community with advice, or is one of the small proportion that should be referred for possible admission.  When NICE produced NG9 "Bronchiolitis in Children" there was a number put on how much feed a baby with bronchiolitis should be taken in order for that to be considered adequate.  Well, that's not quite true.  The guideline uses two numbers and a few words.  So how much do the guidelines say is enough?

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."

Edward Snelson

Disclaimer: If none of this makes sense, the NICE bronchiolitis guidelines are actually very good in my opinion.

  1. Page 16, Full guideline NG9 Bronchiolitis in Children, NICE
  2. Page 18, Full guideline NG9 Bronchiolitis in Children, NICE