1. What is Peak Expiratory Flow?

Peak Expiratory Flow (PEF) is the maximum speed of expiration during forced breathing. It is commonly used to monitor and manage asthma and other respiratory conditions, providing a simple measure of airway obstruction.

2. How Does the Calculator Work?

The calculator uses the PEF prediction equation:

Where:

• \( Height \) — Height in centimeters (cm)
• \( Age \) — Age in years
• \( Gender\ factor \) — 1 for male, 0 for female

Explanation: The equation predicts normal PEF values based on height, age, and gender, accounting for physiological differences in lung function.

3. Importance of PEF Measurement

Details: Regular PEF monitoring helps in asthma management, detecting early signs of worsening, evaluating treatment effectiveness, and guiding medication adjustments.

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). The result shows predicted normal PEF in liters per minute.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal PEF range?
A: Normal PEF varies by individual characteristics. Generally, 80-100% of predicted value is considered normal, while below 80% may indicate airway obstruction.

Q2: How often should PEF be measured?
A: For asthma monitoring, typically twice daily - morning and evening. More frequent measurements may be needed during exacerbations.

Q3: What factors can affect PEF readings?
A: Technique, time of day, recent bronchodilator use, respiratory infections, and environmental factors can all influence PEF measurements.

Q4: Can PEF be used for COPD monitoring?
A: While PEF is primarily for asthma, it can provide some information in COPD, though spirometry is more comprehensive for COPD assessment.

Q5: What should I do if my PEF is below predicted?
A: Consult your healthcare provider. Consistently low PEF may indicate poorly controlled asthma or the need for treatment adjustment.