Predicted Fev1 Calculator

Predicted FEV1 Equation:

\[ Predicted = a \times height^b \times (1 - c \times age) \]

Height:

Age:

years

Constant a:

Constant b:

Constant c:

Predicted FEV1:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Predicted FEV1 Equation?

The Predicted FEV1 equation estimates the expected forced expiratory volume in 1 second based on height, age, and demographic-specific constants. It provides a reference value for assessing lung function and diagnosing respiratory conditions.

2. How Does the Calculator Work?

The calculator uses the Predicted FEV1 equation:

\[ Predicted = a \times height^b \times (1 - c \times age) \]

Where:

\( a \) — Population-specific constant
\( b \) — Height exponent constant
\( c \) — Age coefficient constant
\( height \) — Height in centimeters
\( age \) — Age in years

Explanation: The equation accounts for the relationship between height, age, and expected lung function, with different constants for different demographic groups.

3. Importance of Predicted FEV1 Calculation

Details: Accurate FEV1 prediction is crucial for assessing lung function, diagnosing respiratory diseases, monitoring disease progression, and evaluating treatment effectiveness.

4. Using the Calculator

Tips: Enter height in centimeters, age in years, and appropriate constants for the specific population. All values must be valid (height > 0, age ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What are typical constant values for different populations?
A: Constant values vary by population, age group, and gender. Common values range from a=0.4-0.6, b=2.2-2.4, c=0.004-0.006 for adult populations.

Q2: How does predicted FEV1 help in diagnosis?
A: It provides a reference value to compare against measured FEV1. Values below 80% of predicted may indicate obstructive lung disease.

Q3: Why include age in the calculation?
A: Lung function naturally declines with age, so the equation accounts for this expected decrease in predicted values.

Q4: Are there limitations to this equation?
A: Accuracy may vary for extreme heights/ages, different ethnicities, and individuals with certain medical conditions affecting growth or development.

Q5: Should predicted values be adjusted for altitude?
A: At high altitudes, some adjustment may be needed as lung volumes can be affected by atmospheric pressure differences.