1. What is Peak Expiratory Flow Rate?

Peak Expiratory Flow Rate (PEF) is a measurement of how fast a person can exhale air from their lungs. It is commonly used to monitor and manage asthma and other respiratory conditions.

2. How Does the Calculator Work?

The calculator uses the peak flow equation:

Where:

• \( Height \) — Height in centimeters (cm)
• \( Age \) — Age in years
• \( 5.48 \) — Height coefficient
• \( 0.041 \) — Age coefficient
• \( 1.99 \) — Constant for males

Explanation: The equation predicts normal peak flow values based on height and age, with different formulas typically available for males and females.

3. Importance of PEF Measurement

Details: Regular PEF monitoring helps track asthma control, detect early signs of worsening, and guide treatment decisions. It provides an objective measure of airway obstruction.

4. Using the Calculator

Tips: Enter height in centimeters, age in years, and select gender. All values must be valid (height > 0, age between 1-120). Note that only the male formula is currently implemented.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal PEF value?
A: Normal PEF values vary by age, height, and gender. Typically range from 400-600 L/min for adults, but should be compared to personal best or predicted values.

Q2: How often should PEF be measured?
A: For asthma monitoring, typically twice daily - morning and evening, or as directed by healthcare provider.

Q3: What affects PEF readings?
A: Respiratory infections, asthma exacerbations, technique, time of day, and recent bronchodilator use can all affect readings.

Q4: What is the clinical significance of PEF variability?
A: High day-to-day variability (>20%) often indicates poorly controlled asthma and may require treatment adjustment.

Q5: Are there limitations to predicted PEF values?
A: Yes, predicted values are population averages. Individual "personal best" values obtained when well are more meaningful for monitoring.