Alternative Diagnosis & Co-Morbidities in Paediatrics

True exercise bronchoconstriction typically occurs after 6 -8 minutes of intense exercise, often with true wheeze and some dry cough.

Consider these alternative diagnoses, if history is not clearly suggestive of asthma (Depiazzi et al. 2016):

• Reaching physiological limit due to overweight, unfit or very fit but feels performance should be better
• Reporting of symptoms for the purpose of being excused from sport
• Dysfunctional breathing is common alone but is also more prevalent in people with asthma. May be treated by interested physiotherapist when identified (Barker et al. 2016). Typically, patients who develop non-sports or trigger-related VCD are ‘protocolled’ in ED due to their dramatic symptoms despite normal oxygen saturation levels. Triggers for VCD and other forms of dysfunctional breathing can be performance (sport, singing etc.) family stress, school stress etc.
• Vocal cord dysfunction (VCD) where the ‘wheeze’ identified is actually stridor. The inspiratory nature of sound may not be appreciated. Onset is often soon after starting exercise with limited response to salbutamol treatment.
  
• Exercised induced laryngomalacia (EILM) often identified in elite athletes working very hard. Symptoms are similar to VCD (responds well to surgery).
• A variety of rarer alternative diagnoses include cardiac abnormalities and exercise-induced anaphylaxis

For the above conditions, the most valuable investigation is cardiopulmonary exercise testing (if the child is able to able to perform reliable spirometry). Addition of in-exercise laryngoscopy for suspected VCD/EILM may also be useful, if available.

• Persistent bacterial bronchitis can be either an alternative diagnosis or a co-morbidity (Craven et al. 2013). Typically, includes persistent wet cough most prominent first thing in the morning, when lying in bed and with exercise. May also present as exercise-induced breathlessness due to coughing. Yellowish sputum production containing neutrophils rather than eosinophils, may be detected by microscopy. Consider fibre optic bronchoscopy and lavage if diagnosis is in doubt. Usually responds to an extended course of oral antibiotics (minimum 2 weeks). Broad spectrum antibiotics should be used, unless guided by sputum culture
• Inhaled foreign body can be determined by history +/- changes in chest X-ray. Will not respond to bronchodilator treatment
• Tumours are very rarely associated with progressive cough and dyspnoea. Will not respond to bronchodilator treatment
• Other causes may include cystic fibrosis (CF), primary ciliary dyskinesia (PCD) or bronchiectasis (usually present with wet cough)

• Vocal Cord Dysfunction (VCD) see section above, under exercise limitation
• Structural extra-thoracic airways problem such as sub-glottis stenosis or vocal cord palsy, resulting in a flattened inspiratory flow loop and stridor
• A rare cause of steroid-responsive wheeze is large mediastinal lymph nodes due to lymphoma or atypical mycobacterium infection

• Airways Abnormalities – Tracheobronchomalacia is especially significant. Consider bronchoscopy to diagnose.
• Allergic Rhinitis – Consider anti-histamine or nasal steroid if complaining of nasal or allergic symptoms.
• Sleep Deprivation – May be related to poor asthma control, allergic rhinitis symptoms or low mood.
• Anxiety – See sub-section on Psychosocial Issues in Paediatrics