How important is using a spacer with a metered‑dose inhaler for effective albuterol (salbutamol) administration?

MDI Spacer Use is Highly Important for Effective Salbutamol Administration

Using a spacer with a metered-dose inhaler (MDI) significantly improves lung delivery of salbutamol and should be considered essential for most patients, particularly those with coordination difficulties, children under 4 years, and during acute exacerbations.

Why Spacers Are Critical

Enhanced Lung Delivery and Reduced Oropharyngeal Deposition

Without a spacer, 50-80% of the actuated dose deposits in the oropharynx rather than reaching the lungs 1. Spacers or valved holding chambers (VHCs) dramatically improve this by:

• Improving lung delivery in patients with poor MDI technique 1
• Reducing oropharyngeal deposition by 50%, thereby decreasing local side effects like thrush and reducing systemic absorption of medications with high oral bioavailability 1
• Eliminating the need for precise coordination between actuation and inhalation, which is particularly difficult for young children and elderly patients 1

Recent in-vivo studies confirm these benefits: spacers significantly enhanced lung delivery (measured by 30-minute urinary salbutamol levels) compared to pMDI alone, while simultaneously reducing systemic absorption (24-hour urinary levels) 2.

Clinical Equivalence to Nebulizers

MDI with spacer is as effective as nebulizer therapy for delivering bronchodilators in mild to moderate exacerbations 1. Multiple studies demonstrate:

• No significant differences in hospital admission rates, oxygen saturation, or clinical scores between MDI+spacer and nebulizers 3, 4
• Significantly lower pulmonary index scores and smaller heart rate increases with MDI+spacer compared to nebulizers 3
• Shorter emergency department stays and lower treatment costs with MDI+spacer 4

The British Thoracic Society explicitly states that MDI with spacer is a cheaper and more convenient delivery system than a nebulizer 5.

Specific Populations Where Spacers Are Essential

Children Under 4 Years

• Face masks with VHCs are required for children who cannot use a mouthpiece 1
• Note: Face masks reduce lung delivery by 50% compared to mouthpiece use, but this is still superior to MDI alone 1
• Allow 3-5 inhalations per actuation when using face masks 1

Patients with Coordination Difficulties

• Spacers are specifically indicated for patients who have difficulty performing adequate MDI technique 1
• This includes elderly patients, those with cognitive impairment, and anyone unable to coordinate actuation with slow inhalation 1

Acute Exacerbations

In emergency settings, high doses (4-12 puffs) of β2-agonist through MDI with VHC are recommended for milder exacerbations 6. For acute severe childhood asthma, guidelines explicitly recommend: "Nebulised bronchodilator or, if nebuliser not available, bronchodilator via MDI with spacer" 5.

Proper Technique with Spacers

The optimal technique differs from MDI alone:

• Slow inhalation (30 L/min or 3-5 seconds) followed by 10-second breath-hold 1
• Actuate only once into spacer per inhalation 1
• For antistatic performance, rinse plastic non-antistatic VHCs with dilute household detergent (1:5000 or drops per cup of water) and let drip dry 1

Cost-Effective Alternatives

While commercial spacers (like AeroChamber Plus) demonstrate superior performance, home-made spacers using corrugated tubing or cardboard designs can serve as practical alternatives in resource-limited settings 7, 8. These show clinical equivalence in moderate exacerbations, though commercial spacers deliver slightly higher fine particle doses 2, 9.

Common Pitfalls to Avoid

1. Multiple actuations into spacer: Only actuate once per inhalation, as multiple actuations reduce delivery efficiency 1
2. Delayed inhalation: Inhale immediately after actuation to prevent aerosol settling
3. Using simple tubes instead of VHCs: VHCs with one-way valves are preferred as simple tubes don't eliminate coordination requirements 1
4. Neglecting spacer maintenance: Clean monthly with dilute detergent to maintain electrostatic properties 1

Bottom Line Algorithm

Use spacer with MDI if:

• Age <4 years (mandatory with face mask)
• Poor coordination or technique
• Acute exacerbation (equivalent to nebulizer for mild-moderate cases)
• Elderly or cognitively impaired
• History of poor asthma control despite treatment

MDI alone acceptable only if:

• Adult with demonstrated perfect technique
• Stable asthma
• Patient preference after proper education
• Breath-actuated MDI available (though these cannot be used with current spacers) 1