Preschool Multiple-Breath Washout Testing

Background: Obstructive airway disease is nonuniformly distributed throughout the bronchial tree, although the extent to which this occurs can vary among conditions. Themultiple-breath washout (MBW) test offers importantinsightsintopediatriclungdisease,notavailablethroughspirometry or resistance measurements. The European Respiratory Society/American Thoracic Society inert gaswashout consensus statement led to the emergence of validated commercial equipment for the age group 6 years and above; specificrecommendationsforpreschoolchildrenwerebeyondthescopeof the document. Subsequently, the focus has shifted toMBW applications within preschool subjects (aged 2–6 yr), where a “window of opportunity” exists for early diagnosis of obstructive lung disease and intervention.