Why Children Need Spacers with Metered-Dose Inhalers
Children require spacers (valved holding chambers) with metered-dose inhalers because they cannot coordinate the timing of inhaler actuation with inhalation, and children under 4 years old cannot generate sufficient inspiratory flow to use MDIs or dry powder inhalers effectively 1.
Primary Reasons for Spacer Use in Children
Coordination Problems
Young children and those under 4 years old have fundamental developmental limitations that make proper MDI technique impossible:
- Inability to coordinate actuation with inhalation: The standard MDI requires precise timing—actuating the device during a slow, deep inhalation. This coordination is extremely difficult for young children and elderly patients 1.
- Insufficient inspiratory flow: Most children under 4 years cannot generate the 60 L/min flow needed for dry powder inhalers, making spacers with MDIs the only viable option 1.
Improved Drug Delivery
Spacers fundamentally change how medication reaches the lungs:
- VHCs improve lung delivery and clinical response in patients with poor MDI technique 1.
- Without a spacer, 50-80% of the actuated dose deposits in the oropharynx (mouth and throat) rather than reaching the lungs 1.
- Spacers increase fine particle delivery to the lungs while decreasing wasteful oropharyngeal deposition 2.
Reduced Side Effects
This is particularly important for inhaled corticosteroids:
- Spacers decrease oropharyngeal deposition, reducing the risk of local side effects like thrush (oral candidiasis), throat irritation, and dysphonia 1, 2.
- They reduce systemic absorption of drugs with high oral bioavailability, lowering systemic side effects 1.
Age-Specific Recommendations
Children Under 4 Years Old
- Must use VHC with face mask 1
- Face mask should have a tight fit
- Allow 3-5 inhalations per actuation
- Important caveat: Face mask use reduces lung delivery by 50% compared to mouthpiece, but this is still superior to no delivery at all 1
Children 2-4 Years Old
- VHC with mouthpiece is preferred if the child can cooperate 1
- Slow inhalation (30 L/min or 3-5 seconds) followed by 10-second breath-hold
- Actuate only once into spacer per inhalation
Critical Technical Points
Proper technique matters significantly:
- Actuate only once into the spacer per inhalation—multiple actuations reduce delivery 1
- Use slow, deep inhalation (not rapid) when using spacers
- Clean plastic VHCs monthly with dilute household detergent (1:5000 dilution) and let drip dry to reduce electrostatic charge that can trap medication 1
Clinical Equivalence
Spacers with MDIs are as effective as nebulizers for delivering short-acting beta-agonists and anticholinergics in mild to moderate asthma exacerbations 1. This makes them a practical, portable alternative to bulky nebulizer equipment.
Common Pitfall
Do not assume all spacers are interchangeable. The pairing of a specific pMDI with a specific spacer/VHC should be considered a unique delivery system, as performance varies by device design, material, and valve characteristics 2. Switching spacers may result in reduced medication delivery.
Bottom line: For children, especially those under 4 years, spacers are not optional accessories—they are essential medical devices that transform an otherwise unusable delivery system into an effective treatment method 1.