What is the minimum number of acceptable tests required when performing spirometry?

When performing spirometry, obtaining a minimum of three acceptable tests is important to ensure reliable and reproducible results. Each test should ideally provide a consistent assessment of lung function, allowing for the identification of any obstructive or restrictive lung diseases.

The rationale for requiring three tests stems from the need for accuracy in measurements such as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Variability in respiratory effort, technique, or patient cooperation can lead to discrepancies in results. By performing at least three tests, healthcare providers can compare and average these values to account for any potential outliers and improve diagnostic accuracy.

The three acceptable tests should meet specific criteria, such as maximal effort and consistent results, typically within 5% or 150 mL of one another, to validate that the measurements reflect the patient’s true lung function. This practice enhances the reliability of the spirometry assessment and supports better clinical decision-making.