What are the American Thoracic Society (ATS) criteria for meal timing before spirometry?

ATS Criteria for Meal Timing Before Spirometry

According to the American Thoracic Society (ATS) guidelines, a light meal is acceptable before early morning or early afternoon spirometry tests, but patients should not have exercised vigorously within 2 hours of beginning the test. 1

Specific Meal-Related Recommendations

The ATS guidelines provide clear direction regarding meal consumption before spirometry:

1. Meal timing: A light meal is acceptable before early morning or early afternoon spirometry tests 1
2. Exercise restriction: Patients should not have exercised vigorously within 2 hours of beginning the test 1
3. No large meal restriction: Research has shown that common measures of lung function are not affected by prior consumption of a large meal, making it unnecessary to advise patients to avoid large meals before lung function assessment 2

Additional Patient Preparation Guidelines

For optimal spirometry results, the ATS recommends the following patient preparation steps:

• Clothing: Comfortable clothing should be worn 1
• Footwear: Appropriate shoes for walking should be worn 1
• Walking aids: Patients should use their usual walking aids during the test (cane, walker, etc.) 1
• Medications: The patient's usual medical regimen should be continued 1
• Rest period: The patient should sit at rest in a chair for at least 10 minutes before the test starts 1

Technical Considerations for Spirometry

When performing spirometry, the following technical aspects should be considered:

• Timing consistency: Repeat testing should be performed at approximately the same time of day to minimize intraday variability 1
• No warm-up: A "warm-up" period before the test should not be performed 1
• Reproducibility standard: For clinical trials, a more stringent goal for within-test reproducibility of FEV1 of ≤100 ml should be considered, compared to the 150 ml recommended for general use 1
• Medication considerations: For pre-bronchodilator FEV1, SABA should be withheld for >6 hours and LABA for >12 hours 1

Clinical Implications

The flexibility in meal timing before spirometry testing has important clinical implications:

1. Patient convenience: Allowing light meals makes scheduling more convenient for patients
2. Reduced barriers: No need to fast improves patient compliance with testing
3. Evidence-based approach: Research supports that meal consumption does not significantly affect spirometry results 2

Common Pitfalls to Avoid

• Vigorous exercise: Ensure patients have not exercised vigorously within 2 hours of the test 1
• Smoking: Patients who smoke should be asked to abstain from smoking for at least 8 hours before cardiopulmonary exercise testing 1
• Medication timing: Be aware of bronchodilator use timing when interpreting results 1
• Reproducibility issues: Ensure proper technique to achieve acceptable reproducibility, which has been shown to be achievable in 90-97% of tests even in field settings 3

By following these ATS guidelines for meal timing and other preparation factors, clinicians can ensure optimal spirometry results while maintaining patient comfort and convenience.