Certified Pulmonary Function Technologist (CPFT) Practice Exam

In assessing lung function, what importance does the FEV1/FVC ratio have?

1. It helps determine the presence of restrictive lung disease

2. It is essential for establishing a baseline for treatment

3. It aids in differentiating between obstructive and restrictive airway diseases

4. It is used to monitor response to bronchodilator therapy

The correct answer is: It aids in differentiating between obstructive and restrictive airway diseases

The FEV1/FVC ratio is a critical measurement in pulmonary function tests, particularly in differentiating between obstructive and restrictive airway diseases. FEV1 stands for Forced Expiratory Volume in the first second, while FVC stands for Forced Vital Capacity, which is the total amount of air that can be forcefully exhaled after taking a deep breath. In obstructive lung diseases, such as asthma or chronic obstructive pulmonary disease (COPD), the FEV1 is significantly reduced compared to the FVC, leading to a low FEV1/FVC ratio (typically less than 70%). This is indicative of airflow limitation. Conversely, in restrictive lung diseases, the FVC is reduced, but the FEV1 may also be reduced proportionally, resulting in a normal or slightly decreased FEV1/FVC ratio. Thus, the FEV1/FVC ratio provides essential information that allows healthcare providers to understand the type of lung disease present in a patient, distinguishing whether it is primarily obstructive or restrictive in nature. This differential diagnosis is vital for guiding appropriate treatment and management strategies for the patient.