What is the procedure for performing a bronchodilator test?

Bronchodilator Test Procedure

The bronchodilator test should be performed using a short-acting β2-agonist such as salbutamol (albuterol), with four separate doses of 100 μg administered via metered dose inhaler with a spacer, followed by spirometry testing after a 15-minute delay. 1

Patient Preparation

1. Ask the patient to withhold short-acting bronchodilators for at least 4 hours and long-acting β2-agonists for 48 hours prior to testing 1
2. Have the patient loosen tight-fitting clothing and remove dentures if they are loose 1
3. Record ambient temperature, barometric pressure, and time of day 1
4. Ensure baseline FEV1 is >70% of predicted value for safety purposes 1

Testing Sequence

1. Perform baseline spirometry to obtain pre-bronchodilator values 1

2. Administer the bronchodilator:

   • Use salbutamol (albuterol) as the recommended short-acting β2-agonist 1
   • Administer four separate doses of 100 μg (total 400 μg) via metered dose inhaler with a spacer 1, 2
   • Instruct the patient on proper inhalation technique:
     • Shake the inhaler well before each use 2
     • Hold the inhaler upright with mouthpiece in mouth 2
     • Breathe out fully and comfortably 2
     • While breathing in deeply and slowly, press down on the center of the dose indicator 2
     • Hold breath for up to 10 seconds if possible 2
     • Wait 1 minute between puffs 2

3. Wait 15 minutes after bronchodilator administration 1

4. Repeat spirometry to obtain post-bronchodilator values 1

Interpretation of Results

A positive bronchodilator response is defined as:

• An increase in FEV1 and/or FVC of ≥12% AND
• An absolute increase of ≥200 mL compared to baseline 1, 3

Values less than 8% or 150 mL are likely within measurement variability 1

Important Considerations

• When patients return for repeat testing, ideally use the same equipment and operator, and schedule within 2 hours of the previous test time 1, 4
• The order of pulmonary function tests should be consistent, with bronchodilator testing typically performed after initial spirometry and before diffusing capacity measurements 1
• Proper hygiene and infection control measures should be followed to prevent transmission of infection between patients 1
• For children, especially those with asthma symptoms, more caution is needed as they may have increased sensitivity to bronchodilators 1

Alternative Methods

While metered dose inhalers with spacers are recommended for efficiency and cost-effectiveness 5, nebulized therapy can also be used:

• For nebulized therapy, 2.5 mg of salbutamol can be administered 5
• Nebulized therapy may be less efficient than MDI with spacer in terms of drug delivery and cost 5, 6

By following this standardized approach to bronchodilator testing, clinicians can accurately assess airway reversibility and make appropriate diagnostic and therapeutic decisions for patients with suspected obstructive lung disease.