Ace the CPFT Challenge 2025 – Breathe Easy with Pulmonary Success!

Airflow obstruction in a spirometry test is determined primarily by comparing the Forced Expiratory Volume in one second (FEV1) to the Forced Vital Capacity (FVC), and assessing the FEV1/FVC ratio. In normal lung function, the FEV1/FVC ratio is generally greater than 70% in adults. A reduced ratio indicates that FEV1 is significantly lower in comparison to the FVC, which is characteristic of obstructive lung diseases such as asthma or chronic obstructive pulmonary disease (COPD). This is a crucial metric for evaluating respiratory health and diagnosing conditions that lead to airflow limitation.

While observing changes in lung volume during forced expiration provides data about lung function, it is the FEV1/FVC ratio that specifically highlights the presence of airflow obstruction. Measuring tidal volume and residual volume pertain more to static lung volumes rather than dynamic flow rates involved in obstruction assessments. Evaluating the presence of wheezing and crackles can indicate respiratory issues but lacks the precise quantitative analysis of airflow that spirometry provides. Thus, the correct method for determining airflow obstruction is the analysis of the FEV1/FVC ratio.