Diagnosing asthma in the under 2s

The issue

Many infants have recurrent episodes of cough and wheeze with colds and are completely well in between episodes. They are usually diagnosed as having episodic viral wheezing. A small proportion will have genuine infantile asthma which is difficult but not impossible to diagnose in children under 2 years. Despite what many parents are told, there is certainly no rule that says asthma can not be diagnosed until the child is older.
 

In the past, these children were said to have wheezy bronchitis, however use of the term bronchitis led to widespread use of antibiotics, despite the fact that almost all these episodes are caused by viral and not bacterial infections. In an attempt to encourage use of bronchodilators, it was then emphasised that wheezing equals asthma. This inevitably led to over-diagnosis and many children have been put on inhaled steroids unnecessarily.
 

Making the diagnosis

History – this is usually the key, firstly is it actually wheeze? Many parents report that their child wheezes, when what they are really describing are the harsh sounds of upper airway secretions in the back of the throat. Some will be confusing wheeze with stridor (croup). Asking the parents to record the sounds on mobile phones has proven to be helpful, as are demonstrations of all the noises.
 

There are certain pointers that suggest infantile asthma rather than simple episodic viral wheezing.

  • Family history of atopy - asthma, hay fever or eczema in a parent or sibling.
  • Personal history of atopy – genuine atopic eczema rather than the occasional patch of dry skin, or a proven food allergy.
  • Pattern of wheeze – background daily or nighttime symptoms, or exercise / excitement induced symptoms, rather than the commoner pattern of symptoms only when the child has a viral cold.

Examination is usually normal and unhelpful. Rarely the presence of Harrison sulci indicates chronic respiratory difficulties and is significant. Low height and weight may indicate a more significant underlying condition.
 

Investigations are usually unhelpful. Children under 6 years of age are unable to perform lung function testing. Although the committed allergist may disagree, skin prick testing in this age group is rarely helpful. Furthermore milk allergy is not an issue.
 

If symptoms are marked or atypical, referral to a paediatrician is warranted, particularly one with a respiratory interest. In some cases, further investigations may be performed to exclude less common diagnoses. Gastro-oesophageal reflux must always be borne in mind, as not uncommonly it manifests as recurrent cough and wheeze that has not responded to standard therapy.
 

Treatment of genuine infantile asthma

The single best thing most parents could do to help their symptomatic child is to stop smoking, however this rarely happens. Nevertheless, it is our duty to inform the parents of the harm they are doing to their children (and themselves). In addition, constructive advice should be given to try and help those who wish to give up the habit. Allergy to pets, especially cats may also be a factor, but usually this is in older children. Unfortunately it is rare for parents to remove the offending pet from their home.
 

Salbutamol (the blue inhaler). Bronchoconstricted (narrowed) airways need bronchodilators – but these should only be used on an ‘as required’ basis rather than automatically taken 3-4 times a day. Bronchodilators given in syrup form are far less effective and not worth using, as the dose required orally to have an impact inevitably leads to side effects. The dose is usually 2-6 puffs every 3-4 hours. They should be administered through a spacer device with a mask. There are several of these available on prescription. I find infants tolerate the smaller ones better, and tend to use the AeroChamber®. The orange one has the smallest mask and is usually for infants  under 3 months, the yellow one has the larger mask. By about 3 years of age, most children can use the spacer without the attached mask, which increases the efficiency of lung deposition; for example the blue AeroChamber or my preference, an Able Spacer®. Importantly, lung deposition is drastically reduced if the child screams or struggles with the mask; parents are commonly told the wrong thing, that it is a good time to give the drug when a child is crying! There is no advantage to using a nebuliser at home, compared to a spacer device.


 

Montelukast (Singulair) 4 mg granules can be very useful; it reduces viral airway inflammation and is not a steroid. Rather than using them every day (they are given once daily), since they work within 4 hours they can be started at the beginning of a cold or chest symptoms and continued until the child is better. They must be mixed in cold food e.g. yoghurt, fruit puree, but not hot food nor liquids (they float and don’t dissolve). Parents should be warned that a small proportion of children get bad dreams and disturbed sleep, in which case it should be stopped.
 

Inhaled steroids. A small minority of pre-school children will require regular prophylaxis (a preventer). Inhaled corticosteroids are not too effective for those children who have episodic viral wheeze but are more likely to work in those with genuine infantile asthma. In those with background troublesome symptoms who are using a bronchodilator several times a week, or who are frequently in A&E, or requiring hospital admissions, a trial of inhaled steroids is warranted. Again, these should be administered through a spacer device, with or without a mask depending on age. I tend to use fluticasone (orange inhaler) or beclometasone (beige/brown inhaler). It takes 4-6 weeks to take full effect, so they can not be used just during colds. There is also little point in increasing the dose when the child is unwell with a cough and wheeze. Side effects are rarely seen at standard low doses I use, but we always monitor children’s growth anyway.
 

The outlook

Fortunately the prognosis is generally very good and most will outgrow their symptoms. However although most wheezy infants do not turn out to have persistent childhood asthma, most asthmatics do start wheezing when young. There is nothing to predict what will happen for any individual.