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]