Inhaled therapies and device selection — branching viva

Opening — the eighteen-month-old with no spacer

Examiner: An eighteen-month-old with viral wheeze has been prescribed a salbutamol pressurised inhaler with no spacer. What is the correct device, and why is the spacer essential? ^{[1] [8]}

Candidate (model): The correct device for this age is a pressurised metered-dose inhaler seated in a small-volume valved holding chamber with a tightly-fitting face mask. The spacer is essential because a pressurised inhaler fires its aerosol cloud in under a tenth of a second at high velocity — far too fast for an infant to time to a single breath — so without a spacer most of the dose deposits in the oropharynx and almost nothing reaches the lung. The spacer intercepts the fast cloud, slows and suspends it, so the infant can clear it by slow tidal breathing over around six breaths, with the mask sealed firmly to the face. A dry-powder inhaler would not work at this age because the child cannot generate the inspiratory flow. ^{[1] [8]}