If you don't like what you hear, change the tune. (What to do when you don't hear a wheeze in a child who should be wheezy)

Every now and then, a clinician will go to see a child who appears to have increased work of breathing and is well (in the way that children with viral induced wheeze usually are) but find no wheeze on auscultation.  How strange!

Making a diagnosis is a complex business.  It is such a complicated process that, most of the time, we don't really think about it at all.  This has been described as type 1 thinking (intuitive) in the context of clinical diagnosis. (1)  Most days, I do very little thinking.  When I come across something unexpected or unfamiliar, I am forced to come out of this unconscious automatic mode and think carefully and consciously (type 2 process) about what is going on.  I have to engage my cortex, and it hurts.

So, going back to this little scenario.  Let's say that the child is 2 years old and has has a cold for 3 days.  They are brought by his parents because they have noticed that his breathing is a little fast.  He looks well and is really quite happy with the toys in your room.  Snot bubbles from his nose as he comes and sits on his mother's knee.  Looking at his chest, he has mild subcostal recession and a mild tachypnoea.  When you listen to his chest, you hear...  breathing.

So, what most people do in this circumstance is to listen some more.  It is traditional to check your stethoscope for gremlins or signs of tampering before pushing the earbuds a bit harder into your ears before listening again.  However, there is no getting away from the fact that there is no wheeze, nor is this the silent chest that is so feared in asthma and viral wheeze.  In a silent chest, no breath sounds can be heard and the patient looks awful.  This child has breath sounds and looks well.

How strange.

The reason that it causes us to have a confused moment is that there are certain combinations of signs and symptoms that indicate a particular illness.  That is particularly useful in children's respiratory illnesses since no one sign or symptom is likely to be specific to an illness.  This is why cough and fever do not equal a lower respiratory tract infection.  We need to look for the presence or absence of other features to form a likely diagnosis.

So what we've got now is a mystery illness.  What causes a well child to have respiratory distress without a wheeze or stridor?

Your next move is simple.  Give the child inhaled (or nebulised if necessary) β-agonists.  I would go with 10 puffs of salbutamol via a spacer device.  Then sit back and watch the magic.

What will probably happen next is a little surprising the first time you experience it: a wheeze appears.  More importantly, the child's breathing improves.  So, what is going on here?

The answer to that would be science.  Science and music are happening and it goes like this:  In order to have a wheeze, there must be the correct conditions for this to occur.  A musical note needs the right amount of air flowing through a tube in the right sort of way.  The size of the tube matters quite a lot.  Ask any wind musician or organ player.

In these cases there is bronchospasm (caused by viral infection) but the conditions are not right to produce a wheeze for you to hear.  Of the parameters that affect the musical note (length of tube, diameter of tube and flow of air) you can change two with β-agonists.  You can't change the length of the tube but the other factors should respond nicely.

So, if you don't like what you hear, change the tune.  When your clinical diagnostic brain tells you that there should be a wheeze, you are probably correct.  If you were expecting a wheeze but don't hear one, by all means rethink your presumption.  If you are left with the same conclusion, then try the β-agonist trick.  It works a treat.

Edward Snelson
Soverynotamusician
@sailordoctor

Disclaimer: This is a very different thing from rechecking a blood pressure until you get the number that you want.  Very different.   Anyway, I would never do that.

Reference

1. Croskerry P, A universal model of diagnostic reasoning, Acad Med. 2009 Aug;84(8):1022-8.

Croup - proof that a number is never enough information

Croup has to be one of the easiest upper respiratory tract infection diagnoses to make.  You can literally hear the child coming.  The classical croup picture is one of a child who has a cold for a few days and then develops a cough that sounds like a seal.  Although there are differentials listed in the textbooks these can also be excluded clinically:

• Inhaled foreign body - has not inhaled a foreign body
• Bacterial tracheitis and epiglottis - child does not look that unwell and is able to swallow their own saliva

So, it is a simple case of, "this is croup!"  The next job is that you have to ask yourself how bad the croup is.  The good news is that there are scoring systems available.  The problem with scoring systems is that they create the impression that the game is over.  It really isn't.

If you do use a croup score, you should see it for what it is: a snapshot which attempts to quantify what you see and hear.  As is often the case, these scoring systems are developed for the purposes of research and have been adopted into clinical practice.  It is equally valid to take the signs and symptoms and qualify these into a mild, moderate or severe croup.  You might find a scoring system helpful but it is not mandatory.  Whether you use a qualitative or quantitative method, the severity is only part of the picture.

One thing that guidelines often struggle to emphasise well is the importance of the trajectory.

All three children in the figure above have a Westley croup score of 4 when seen by a clinician.

Child A was found in the morning with a stridor and significant respiratory distress. As often happens, when the parents rushed the child to be seen, child A improved and now has the tail end of a soft stridor.

Child B was coughing, had a soft stridor all night and refuses to move out of croup limbo.

Child C was not so bad when they set off to see you but has got noticeably worse in the time leading up to the consultation. The game is just beginning for child C.

The score (or your qualitative mild/ moderate/ severe assessment) and the trajectory are the most important factors. I would also consider risk factors including co-morbidities and previous life threatening episodes of croup.

That brings us to croup management-

Turbulent flow of air creates more than twice as much resistance as laminar air flow. Children who have croup will tend to position themselves and breathe optimally if left alone to do so. Distressing the child either directly or via the parent can cause sudden decompensation.


If the child is in the severe category then facial oxygen should be given followed rapidly by nebulised adrenaline (epinephrine). Doses as per your formulary but at the time of writing that is 5mg for a child 2 and up where I work.  If not already at hospital, a child with severe croup should be moved there quickly. If already in an ED then the child may need further escalation but in many cases the adrenaline will buy time and avoid the need for airway management.


For mild and moderate croup the best evidence is for systemic steroids.(1)  There is evidence that dexamethasone is more effective than prednisolone.(1) Studies have also compared different doses of dexamethasone and found that there is no difference between giving the larger dose 0.6 mg/kg and the smaller dose 0.15mg/kg.(1) I have been using the lower dose for many years but have no hesitation in repeating the dexamethasone if the child vomits afterwards and it is uncertain as to whether the first dose stayed down.


Be warned, my GP land colleagues: dexamethasone liquid can be difficult to source from community pharmacies. NICE says that "Providers of urgent care services should ensure that dexamethasone is available."(2)  This may not be within your control.  Unless you know that your patients can get it easily, prednisolone may be the pragmatic choice.

I am very aware that treating mild croup is a relatively new phenomenon. If you fear change, please take comfort in knowing that I do too. However my dislike of medicalising childhood illnesses does not extend to croup. This is for two reasons. The first is to do with the aforementioned trajectory. I don't know which mild croups are going to become moderate or severe but some will and theses children may become victims of another fact of science.

The flow of air through a tube is reduced by the reduction in diameter to the power 4. If a child with croup gets worse and their airway haves in diameter then they will only be able to shift one sixteenth of the air. If that air flow becomes turbulent then you won't need a score to tell you how bad they are. So mild croup is not a thing to dismiss. It is level one of the game of croup. Level 1 is deceptively easy but unlike most games, level 2 is much harder and level 3 completely unexpected.

Edward Snelson
@sailordoctor

Disclaimer: It's not a game.

References:

1. Cochrane library review, Glococorticoids for croup
2. NICE, Clinical Knowledge Summary for Croup

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
@sailordoctor

Disclaimer: I fear change

References

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

The TPR paradox - how do I know if a child might have sepsis?

When I assess an ill child, I am primarily making a decision about whether the child has possible sepsis.  To a certain extent, everything else is detail.  The sepsis question determines which door the child leaves through.  Just like in primary care, I send the vast majority of children presenting to the ED back out the way they came, whether they have pneumonia, urinary tract infection or just a cold.  A small number of ill children are admitted, with the possibility of sepsis as the primary reason.  The question is: How do I decide which door to send each child through?  Once you answer that, I believe that you can begin to understand how to use the many guidelines and decision tools designed to help us make this choice.

In 1935, Einstein and two of his buddies published a paper detailing some problems with quantum physics theories.  In effect they were saying that their own advances had explained a lot about how physics worked, but that there were some things that they could not explain.  Specifically, when two particles went through two doors, one of them did something that didn't make sense.  You could do something to one of the particles and the other reacted even though they are not connected.  This is called the EPR paradox, after Einstein, Podolsky and Rosen.  These three were the best scientific minds in the world and yet they had a missing piece of the jigsaw so big that it called everything else into question.

I believe that we are in a similar place in medicine when it comes to recognising possible sepsis in children.  Once again we have two doors and sending children through these is not as straightforward as it should be.  We all do our best to send each child through the correct door.  There is a big piece of the jigsaw missing though and that’s got us all scratching our heads.  The missing bit is knowing how to go from considering possible sepsis to diagnosing probable sepsis without resorting to reading tea leafs or other substitutes for a valid test.  Most of the time we do our best and accept that in the absence of a good test all we have is good judgement.  The problem comes when a child dies of sepsis and that gap in the process comes under scrutiny.  I'm all for completing the puzzle but I am suspicious that we are trying to put the wrong piece into the gap.

If I asked you to create a decision tool for clinicians to move from considering sepsis to a provisional diagnosis of sepsis, what would you choose as predictors?  You could use the appearance of the child but that is difficult to quantify.  What seems far more reliable is TPR (temperature, pulse and respiration) since these can be measured.  The trouble is that the most measurable features of your assessment are the least reliable.

Before I get a rush of people saying that I think that you should ignore tachycardia and high temperature, please be clear that I don’t think that.  It is just that I think that there is a much better category of evidence and that numbers are not as reliable as we want them to be.

There are plenty of reasons to mistrust numbers.  For starters we have a lack of reliable reference ranges.  There is a good reason why no-one has started making a lot of money out of selling centile charts of paediatric heart and respiratory rates.  They don't exist.  There is not enough evidence to produce such a thing.  The variables are just too many.  Is it age that determines heart rate or your weight?  If it is weight then is it lean weight?  What is the effect of anxiety on heart rate?  How different is a normal heart rate in a resting child to that of a playing child or a screaming child?

What about those normal ranges that you have somewhere when you need to check?  Aren't they evidence based?  You could try to find out what their evidence base is but I could probably save you a lot of hassle by telling you that all the normal ranges that I know of are based on consensus, which is why they are all slightly different from each other. In the past few years, two large analyses have shown that some of the most commonly available reference ranges map poorly to population studies.  Even then, these publications acknowledge that the populations studied are never truly normal. (1,2)

However, I think that this whole issue is much simpler than all of that, because the wrong question is being asked.  The question is not, “Does this child have sepsis?”  The question is, “Can I say with confidence that this child does not have sepsis?”  When we use the rule out rather than rule in approach, everything starts to fall into place, including the value of numbers.

I said before that there is more reliable evidence than temperature and pulse.  That evidence is something that you rely on every time you assess a child and it is the thing that makes sense of the numbers for you: activity.   What we really want to know about the heart rate and capillary refill is not the absolute number but the effect that these are having.  What we need to assess is oxygen and glucose delivery to the organs and there is no better measure of this in a child than what the child can do once these get there.

There is one more variable which complicates the TPR paradox, which is the up and down nature of the illness.  You may see the child at their worst or possibly their best.  In any viral illness the likelihood is that the child will have extremes of activity making nonsense of the assessment.  Thankfully we have two saving graces here.  The first is that we can hear about what has gone before.  The second is that we are able to continue the assessment either by observing, referring or safety netting.

So let’s bring all of this together.  There are two simple elements to recognising serious infection in children.  The first is a hierarchy of evidence.  The second is a rule-in/ rule-out approach.

The hierarchy of evidence is logical.  If I see a child in a playground climbing up to go on the slide and their parent mentions that they have had a temperature, I don’t worry that they may be septic.  I do imagine that they have a significant tachycardia but this will be a result of their activity and possibly their temperature.  I see with my eyes both the activity and the vigour with which it is undertaken.  I don't need to ask any questions or measure any physiological parameters because I have all the evidence that I need.

If I was giving telephone advice and I hear that a child is sat playing on a tablet I now have some very useful information about the adequacy of their brain’s perfusion and oxygen/glucose supply.  It's not as good as what I see because I can't scrutinise what I am being told with my own experienced eye.

Finally if I measure a child’s heart rate and capillary refill, I have information but it needs to be put into context.  Was it cold outside?  Have they just been upset by something?  So the numbers are important but I need what I see and hear to make sense of them.

In any acute assessment of an unwell child this hierarchy can be combined with a rule-in/ rule-out approach to answer the question, “Am I certain that this child does not have sepsis?”

If what you see, hear and measure is all reassuring then the answer is yes, they do not have sepsis.  If what you see, hear and measure are all concerning then the answer should be no, they could well have sepsis.  If what you see, hear and measure give a mixed message then the question remains open and there are various ways to answer it.  Using the hierarchy of evidence above, I feel confident to give paracetamol and wait when a child looks well and behaves well even if they are febrile and tachycardic.  The options are always the same: discharge with safety netting advice, observe, discuss or refer.

Just like the scientists of 1935, none of us has all the answers.  None of the decision tools available is even close to perfect and all of them rely on someone at some point taking responsibility for making a decision about which door the child will go through.  Thankfully the majority of children answer the question for you.

Edward Snelson

@sailordoctor

If you liked this you might also like:

In Praise of Doing Nothing (Easter Egg – good safety-netting and saving lives)

Or How special is your patient? - (Neonates and other patients who don't follow the rules)

References:

(1) Fleming S et al, (2011). Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies. The Lancet, Vol 377, no 9770, 1011-1018.

(2) O'Leary F et al (2015) Defining normal ranges and centiles for heart and respiratory rates in infants and children: a cross-sectional study of patients attending an Australian tertiary hospital paediatric emergency department, Arch Dis Child, 100, 733-737

  

More?!? The Salbutamol Paradox

Dosing in children is quite frankly a nightmare.  While formularies such as the BNFc are excellent and easy to follow, there are always pitfalls.  There are maximum doses and there are age related doses, weight related doses and doses that are the same at any age or weight.

Despite all the potential to get it wrong, I am pleased to report that with very few exceptions, the children presenting to the Paediatric Emergency Department where I work are prescribed the correct doses of their medicines.  This is less often the case for inhalers.  It is not uncommon for me to send a 2 year old child home with instructions to continue salbutamol (via a spacer of course) four puffs four hourly and then have another health care professional advise the parent that this is too large a dose.  If the next healthcare professional that they see applies the 'smaller children need smaller doses' principle, the parent may be advised to reduce the amount of bronchodilators to two or even one puff every four hours.

I can see the logic there.  Why would you give more puffs of inhaler to a 2 year old than a 20 year old?  Inhaled bronchodilators are a perfect example of why therapeutics in children is not governed by one or two simple principles.  In the case of treating wheeze in children it is not the size of the child or the age of the age of the child.  Once more we must turn to physics for the answer.

Delivery of the bronchodilator to the airways of the lung works best when you have good inspiration, without turbulence, through open tubes.  In a two year old, you have none of these things.  Crying looks as though it should do the job but studies have shown this to be wrong.  Aerosol deposition during crying is poor.  Even if the child is complying, they are still a victim of physics.  The flow through any tube is inversely proportional to the diameter to the power four.  This means that if the wheeze has halved the diameter of a bronchus, one sixteenth of the air will get through.  If there is turbulence of that air flow then the flow is at least halved again.  So, assuming mucous is rattling around, it doesn't take much bronchospasm to reduce the air getting to your alveoli substantially.  When you are two years old, your trachea is about 6-7mm internal diameter and your bronchi even smaller, so any reduction from bronchospasma and mucous is going to have a huge impact.

Suddenly four puffs doesn’t seem like a lot to give.  I wonder if we studied the salbutamol paradox properly if we would find that there is an argument for age banding salbutamol reliever puffs so that we give even more to the under 5 year olds as a standard reliever dose.

Edward Snelson

Using Real Science to save small lives

@sailordoctor

Disclaimer:   None of the children in medical research have ever consented to being a point mass in a vacuum. 

The Salbutamol Paradox is based on the ladder paradox, a physics thought experiment that involves getting something that seems too big into what appears to be too small a space.  Just like the ladder paradox, the salbutamol needed for a child's wheeze goes up substantially as the pace of the clinical scenario increases.

Schrodinger’s Safeguarding Case

Whether you've been practising medicine for 30 minutes or 30 years, dealing with the issue of safeguarding is one of the biggest challenges for any of us.  We are told that there are several must do’s such as:

Wait a minute...   I know the list goes on but those first two are quite enough to deal with before we process any more.  What those two statements mean in practice is that the minute I've thought of a way that this could be a safeguarding issue, I am doing mental gymnastics trying to figure out the following things: 

If this comes easily to you then you have my admiration.   For the mortals among us it is so challenging that at some point most of us have wished that there was no concern or that we didn't have to be the one that brought it up.  You have to be careful though, because when you find yourself wishing for these things you might just do something to make them happen.  It is within your power to explain the concern away.  It is possible to refer to someone else who will take your concern further without telling the parents.  Neither of these are good ‘ways out’.

The problem is that we often see the way forward as a choice or a judgement on the situation.  This choice forces us to feel as though we are choosing sides which is intuitively at odds with our instinct to be on the side of the parents.

There is a solution that I believe does work: Schrodinger’s safeguarding.   [If you don’t know about Schrodinger’s cat (a mixture of quantum physics and animal abuse that makes sense in a strange way) then don’t worry.]  The principle that I want you to get you head around is this:

In this way you can overcome all the barriers to dealing with the problem.

Because you treat the concern as fully real:

• You will act in the best interest of the child.  You will explore the concern until satisfied.
• You will involve all the right people.
• You will ask all the right questions and document things in far more detail than you would normally.
• You will tell the parents that you have a concern because you can’t do the first three things adequately without them noticing that something is going on.

Because you treat the concern as fully false you will come across differently and the parents will sense your open-mindedness:

• You will come across as non-judgemental.   You will be able to be matter of fact about the need for the safeguarding concern to be raised and answered and they will sense that you have not judged them.
• You will keep the health of the child as a top priority.  The parents will have come with their own agenda and you will remember to address that just as you would have normally.  This also helps parents to see that you have not de-humanised them.

So next time you have a safeguarding concern, do put it back in the box.  Not a Pandora’s box but a Schrodinger’s box.  You're not making a judgement but you do need to do both of your jobs.

Edward Snelson

@sailordoctor

Disclaimer:  Damn it Jim, I'm a doctor not a quantum physicist.