What are the pre-test restrictions for a pulmonary function test (PFT)?

Pre-Test Restrictions for Pulmonary Function Testing

Patients should avoid smoking within 1 hour, alcohol within 4 hours, vigorous exercise within 30 minutes, wearing restrictive clothing, and eating large meals within 2 hours before pulmonary function testing. 1

Key Restrictions Before PFT

• Smoking: Avoid smoking for at least 1 hour before testing 1
• Alcohol: Avoid consuming alcohol within 4 hours of testing 1
• Exercise: Avoid vigorous exercise within 30 minutes of testing 1
• Clothing: Wear loose-fitting clothing that doesn't restrict full chest and abdominal expansion 1
• Food: Avoid eating a large meal within 2 hours of testing 1
• Caffeine: Avoid consuming caffeine within 2 hours of testing 2

Medication Considerations

Bronchodilator Management

The decision to withhold bronchodilators depends on the clinical question being addressed:

• For diagnostic testing: Withhold bronchodilators to diagnose underlying lung conditions 1

  • Short-acting inhaled bronchodilators (e.g., albuterol/salbutamol, ipratropium): Withhold for at least 4 hours 1
  • Long-acting β-agonists (e.g., salmeterol, formoterol): Withhold for at least 12 hours 1
  • Oral medications (aminophylline, slow-release β-agonists): Withhold for at least 12 hours 1

• For therapeutic assessment: Continue medications if testing is to determine response to current treatment regimen 1

Patient Preparation on Arrival

• Verify compliance with pre-test restrictions and document any deviations 1
• Ask patients to loosen tight-fitting clothing 1
• Dentures should generally remain in place unless they are loose and interfere with test performance 1
• Ensure patient is relaxed before and during the test 1

Testing Environment and Timing

• Record ambient temperature, barometric pressure, and time of day 1
• For follow-up testing, ideally use the same equipment and operator 1
• Schedule repeat testing within 2 hours of previous test times 1

Testing Sequence

A recommended order for pulmonary function tests is:

1. Dynamic studies (spirometry, flow-volume loops, peak expiratory flow)
2. Static lung volumes
3. Bronchodilator administration (if used)
4. Diffusing capacity
5. Repeat dynamic studies (if bronchodilator was given) 1

Common Pitfalls to Avoid

• Failing to document recent bronchodilator use before testing 3
• Unnecessarily withholding medications in patients with severe respiratory disease who may experience significant symptoms 3
• Not maintaining consistent pre-test conditions for serial monitoring, which can affect result comparability 2
• Overlooking the importance of proper patient positioning - testing should be performed in the same position (sitting or standing) for longitudinal studies 1