What is the first step in interpreting spirometry results?

Interpreting spirometry results begins with assessing the FEV1/FVC ratio because it provides crucial information about the type of respiratory disease present. The FEV1 (Forced Expiratory Volume in one second) measures how much air a person can exhale during the first second of a forced breath, while FVC (Forced Vital Capacity) measures the total amount of air exhaled during the forced breath.

The FEV1/FVC ratio is essential in differentiating between obstructive and restrictive lung diseases. In obstructive diseases, such as asthma and COPD, the FEV1 is significantly reduced compared to FVC, leading to a decreased FEV1/FVC ratio. Conversely, in restrictive disorders, both FEV1 and FVC are reduced, but the ratio may remain normal or elevated. Therefore, evaluating the FEV1/FVC ratio first allows the clinician to quickly categorize the nature of the lung problem and guide further steps in the evaluation and management.

After determining the FEV1/FVC ratio, clinical interpretation can proceed by evaluating FVC levels for its significance and potential limitations, checking for bronchodilator reversibility to assess ongoing airway obstruction, and ultimately comparing the results against normative values considering the patient's age and other demographic