Discussion and Answers

This real case presented to me recently.

I hope you have realised that this is a pretty sick baby! I chose this case because the diagnosis was not obvious, and not typical for a baby of this age.

What is the most likely diagnosis?

Based on the information available in the first question the correct answer is bronchiolitis. In the context of preceding URTI symptoms, this is the most likely diagnosis of gradually worsening respiratory distress in infants under 12 months of age. It is more common in winter, at should be at the top of your list of differentials for a baby that can’t breathe.

Epiglottitis is unlikely in a fully vaccinated child, and unlikely without fevers. Croup is a possibility, but more common in older children, and there has not been the classical “barking cough”.

Pneumonia is also possibility, certainly in the context of other respiratory symptoms, and gradually worsening SOB. But it is less likely when there has not been a fever, and less common than bronchiolitis in this age group.

Inhaled foreign body is another possibility, especially given the “sudden” onset nature of the symptoms of increased WOB. However, the baby is not yet mobile at this age, and so not likely to be able to get their hands on something that they might swallow.

Tonsillitis can cause an oral obstruction  – with the inability to swallow solids and / or liquids (including saliva), but does not usually cause airway obstruction or airway symptoms.

Upper or Lower airway?

OK – you got me. I’m being sneaky. Yes the answer to the first question should be bronchiolitis – which is a lower airway problem. But now we have examined the baby, it is much more likely to be an Upper Airway Obstruction. 

  • Stridor is a feature only of upper airway obstruction, most commonly seen with croup, but also present in epiglottis and inhaled foreign body
  • The “see-sawing” of the chest and abdomen, and the deep chest recessions suggest an upper airway problem – this poor baby is trying really hard to suck in air!
  • The respiratory rate, although elevated, is not that high. In Bronchiolitis, and to a lesser extent, pneumonia, the respiratory rate is likely to be greater, as in lower respiratory tract disorders gas exchange will be affected. It is not uncommon for bronchiolitis babies to have respiratory rates of 60 or 70.
  • There are no focal signs on the chest. Pneumonia will likely present with crackles, and maybe some wheeze, and bronchiolitis is also sometimes wheezy (although often always).
  • The cough is weak because baby is not able to make a strong cough due to shortness of breath
  • An active baby, moving all 4 limbs suggests they are not (yet) completely systemically unwell – thus more likely to have an airway obstruction, rather than a systemic illness

Management

This question presumes you have deduced the most likely diagnosis – which is croup. The other main differentials for an upper airway issue are inhaled foreign body or epiglottis.  The gradual worsening of the symptoms means that inhaled foreign body is less likely – this would usually be sudden onset without subsequent worsening in symptoms – occasionally symptoms may subsequently improve if the object dislodges and then gets stuck lower down the airway. Also, the baby’s age – only 5 months – mean that the baby is not yet mobile, and so it unlikely to have got their hands on an object that they could have put into their mouth or nose.

Epiglottis is very rare in vaccinated babies (and in developed countries in general). It also usually presents with fevers, and this child has not had any.

The ‘first step’ in management is always a tricky question. In reality, we do multiple things in conjunction. The correct answer is to give nebulised adrenaline. This will act quickly (although may not last very long), and may prevent any further deterioration of the airway. This baby should also receive a dose of steroids (usually dexamethasone orally) as soon as possible. This usually works within about 30 minutes and reverses the airway swelling.

Giving oxygen is a good idea, and should also be done in conjunction with the other two steps, but that is not going to affect the cause of the airway obstruction, and in this case, the baby’s sats were normal.

In a floppy baby in severe cases the first action will be to intubate and ventilate.

In real life, we also placed this baby onto high flow nasal oxygen, at 21% (room air). This provide a degree of PEEP and helps to reduce the work of breathing – although this is typically indicated for a lower airway problem (such as bronchiolitis) it is also appropriate to use in any cause of increased WOB.

It is also important to try not to distress the child. Distress can worse then symptoms.

With these measures, the mottling and capillary refill quickly returned to normal. If they hadn’t, then IV access should be gained and a stat bolus of fluids given. In sick babies, this peripheral shutdown may be indicative of dehydration but should always be interpreted a sign of being generally unwell.

Within 15 minutes with the above treatment, the baby was much improved, and was feeding hungrily. If they had not been able to tolerate oral intake, then NG or IV fluids would be appropriate. NG is usually preferred if it can be tolerated i.e. not vomiting). They were admitted to the paediatric high care ward.

Ongoing management would involve further adrenaline nebs as required, and possibly further doses of steroids, up to a maximum dose of 0.6mg/Kg (typical dose in mild croup is 0.15mg/Kg).

For more information on the causes of infant airway obstruction, see the article Laryngeal and Tracheal Infection

Image – for illustration purposes only. Not related to child depicted in this case. Photo of baby by koka_sexton on flickr. Used under CC 2.0 license. 

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