Home
Back
Spirometry Formula:
| From: | To: |
The FEV1/FVC ratio is a measurement used in pulmonary function tests to assess lung function. FEV1 (Forced Expiratory Volume in 1 second) is the volume of air that can forcibly be blown out in one second. FVC (Forced Vital Capacity) is the total amount of air that can be forcibly exhaled. The ratio between these two values helps diagnose obstructive and restrictive lung diseases.
The calculator uses the simple formula:
Where:
Interpretation: A normal FEV1/FVC ratio is typically 70% or higher. Values below 70% suggest an obstructive pattern seen in conditions like COPD or asthma.
Details: Spirometry is a fundamental pulmonary function test used to diagnose and monitor respiratory conditions. The FEV1/FVC ratio is particularly important for identifying obstructive lung diseases where airflow limitation is present.
Tips: Enter FEV1 and FVC values in liters. Both values must be positive numbers. The calculator will compute the ratio and provide a basic interpretation based on standard clinical thresholds.
Q1: What is a normal FEV1/FVC ratio?
A: A normal FEV1/FVC ratio is typically 70% or higher in adults, though this can vary slightly with age.
Q2: What does a low FEV1/FVC ratio indicate?
A: A ratio below 70% typically indicates an obstructive pattern, suggesting conditions like COPD, asthma, or bronchitis.
Q3: Can this calculator diagnose lung disease?
A: No, this calculator provides a basic ratio and interpretation. Formal diagnosis requires comprehensive pulmonary function testing and clinical evaluation by a healthcare professional.
Q4: How does age affect the FEV1/FVC ratio?
A: The ratio naturally decreases with age. Some experts suggest using age-adjusted lower limits of normal rather than a fixed 70% cutoff, especially in older adults.
Q5: What's the difference between obstructive and restrictive patterns?
A: Obstructive patterns show reduced FEV1/FVC ratio (<70%) while restrictive patterns typically have a normal or increased ratio but reduced FVC.