Inhaled therapies and device selection — formative SAQs

SAQ 1 — Choosing the device across childhood (10 marks, 15 minutes)

Stem: A general paediatric clinic sees three children on the same morning: an eighteen-month-old with viral wheeze, a five-year-old with preschool wheeze, and a twelve-year-old with established asthma. Outline the age-based device ladder, the breath action expected at each step, and the principle that governs each transition. [1] [3]

Model answer

The ladder and the breath action (5 marks). The devices are matched to the child's age, inspiratory flow and coordination. The infant and toddler under about four years uses a pressurised metered-dose inhaler seated in a small-volume valved holding chamber with a tightly-fitting face mask; the dose is fired into the chamber and cleared by slow tidal breathing over around six breaths per actuation, the mask held firmly to the face. The preschool child, about four to six years, moves to a spacer with a mouthpiece, taking one to two slow deep breaths with a short breath-hold per actuation; a dry-powder inhaler is usually still too demanding. The school-age child, from about six years, can use a dry-powder inhaler if inspiratory flow is adequate — one sharp, deep inhalation then a breath-hold — or continue a spacer and pMDI. The adolescent, twelve years and over, can use any device, and the choice is increasingly driven by adherence. [1] [3]

The principle governing each transition (3 marks). Each step is a clinical judgement of the individual child, not a fixed birthday. The mask-to-mouthpiece transition depends on the child forming a reliable seal around the mouthpiece for the whole dose. The spacer-to-dry-powder-inhaler transition depends on generating the inspiratory flow — roughly thirty to sixty litres per minute — needed to de-aggregate the powder. A dry-powder inhaler given to a child who cannot generate that flow delivers almost nothing. [1] [3]

Teaching and review (2 marks). Technique is taught by demonstration and return-demonstration (teach-back) at every visit, because technique drifts and the child grows out of one device into another. After an inhaled corticosteroid the child rinses and spits to prevent oral candidiasis, and the dose counter is checked. [3]

SAQ 2 — A 'failing' preventer and the acute-asthma device choice (10 marks, 15 minutes)

Stem: A nine-year-old on a regular inhaled corticosteroid via a spacer reports worsening control and rising reliever use; on review she admits she often uses the inhaler without the spacer. Separately, a six-year-old presents to the emergency department with a moderate acute asthma exacerbation. Address (a) the assessment of the failing preventer before escalating the dose, and (b) the first-line reliever device route for the acute child, with the evidence. [1] [5]

Model answer

Assessing the failing preventer (5 marks). The first principle is that the commonest reason an inhaled corticosteroid appears to fail is poor delivery, not an inadequate dose. Here the child admits using the inhaler without the spacer, which fires a fast aerosol cloud that deposits most of its dose in the oropharynx and delivers little to the lung. The assessment is to watch the child take the dose: check the seal (mask or mouthpiece), the actuation (shake, one puff at a time into a seated chamber), the breathing pattern (slow deep breaths with a breath-hold), and the spacer itself (primed and static-free). Confirm the dose counter and rinse-and-spit after the corticosteroid. The plan is to correct the technique and re-assess control over two to four weeks before escalating the drug, while also excluding the non-adherence, wrong-diagnosis (foreign body, malacia, protracted bacterial bronchitis) and genuine-severity causes of poor control. [1] [3]

The acute-asthma device route (5 marks). For most children with acute asthma, salbutamol by pressurised inhaler and spacer is the first-line route: the Cochrane review of holding chambers versus nebulisers for beta-agonist treatment of acute asthma found the spacer at least as effective as the nebuliser, with fewer side-effects such as tremor and tachycardia and a shorter emergency department stay, and randomised trials in severe exacerbations have shown the inhaler-and-spacer route to be superior. The dose is given one actuation at a time into the spacer, cleared by the breaths, and repeated over the first hour per the local acute-asthma guideline. The oxygen-driven nebuliser is reserved for the child who is hypoxic, exhausted or unable to coordinate the spacer — it is not a more powerful version of the spacer, and oxygen should never be withheld to wait for one. Add ipratropium bromide for severe exacerbations. The exact age-stratified puff counts must be verified against the current Australian Asthma Handbook or local protocol before use; the principle to defend is the route and the oxygen. [5]