Peak Flow Meter: Essential Guide
A complete practical resource for parents, caregivers, and healthcare professionals
A peak flow meter is a handheld medical device that measures how fast air can be pushed out of the lungs. It is an essential tool for monitoring and managing asthma in children, helping to detect airway narrowing before symptoms become severe. This guide provides complete information on using peak flow meters safely and effectively.
What is a Peak Flow Meter?
A peak flow meter measures Peak Expiratory Flow Rate (PEFR or PEF), which is the maximum speed at which a person can exhale air after taking a deep breath. The measurement is recorded in liters per minute (L/min).
When airways become narrow due to asthma, less air can be pushed out quickly, resulting in lower peak flow readings. Regular monitoring helps track lung function and can provide early warning signs of worsening asthma, often before symptoms appear.
Purpose and Where They Are Used
Primary Uses
Peak flow meters serve several important purposes in asthma management:
- Monitor daily lung function and detect changes in airway status
- Identify early warning signs of asthma flare-ups before symptoms worsen
- Assess response to rescue medications during acute episodes
- Help determine when to adjust medications or seek medical care
- Track asthma control over time and identify trigger patterns
- Provide objective measurements for children who cannot communicate symptoms well
Common Settings
- Home use for daily monitoring
- Schools and daycare centers
- Pediatric clinics and hospitals
- Athletic facilities for children with exercise-induced asthma
- During travel when away from regular healthcare providers
Types of Peak Flow Meters
1. Manual (Mechanical) Peak Flow Meters
These traditional devices have a sliding marker that moves along a numbered scale when the child blows into the mouthpiece.
Features:
- Simple design with visual indicator
- No batteries required
- Portable and lightweight
- Lower cost (typically $20-50)
- Readings must be recorded manually
2. Digital Peak Flow Meters
Electronic devices that display readings on a digital screen.
Features:
- Digital display screen
- May store multiple readings with date and time stamps
- Some models measure both PEF and FEV1 (Forced Expiratory Volume in 1 second)
- May include data tracking features
- Requires batteries
- Higher cost (typically $50-100)
Range Categories
| Type | Range | Suitable For |
|---|---|---|
| Low Range | 30-400 L/min or 50-390 L/min | Small children, young children, individuals with severe airflow obstruction |
| Standard (Full) Range | 60-880 L/min or 60-810 L/min | Older children, teenagers, adults |
How to Use a Peak Flow Meter: Step-by-Step Guide
Before You Start
- Remove any food or gum from the child's mouth
- Have the child stand up or sit up straight
- Ensure the device is clean and the indicator is at zero
Taking a Reading
Establishing Personal Best Peak Flow
To find your child's personal best peak flow number:
- Take readings 2-4 times daily for 2-3 weeks when asthma is well controlled
- Record all measurements in a diary
- Use the same peak flow meter for all readings
- Take readings at consistent times (such as morning and evening)
- The highest number during this period is the personal best
Normal peak flow values vary by age, height, and gender. However, comparing your child's readings to their own personal best is more useful than comparing to population averages.
Understanding Peak Flow Zones
Peak flow zones use a traffic light system to help determine what action to take. These zones are based on percentages of your child's personal best peak flow.
Green Zone: All Clear (80-100% of personal best)
What it means: Asthma is under good control. Airways are open.
Actions:
- Continue regular controller medications as prescribed
- No symptoms or only minor symptoms
- Child can perform normal activities
- Avoid known asthma triggers
Yellow Zone: Caution (50-80% of personal best)
What it means: Airways are starting to narrow. Asthma is not well controlled.
Symptoms may include: Coughing, wheezing, chest tightness, shortness of breath, difficulty with activities or sleep.
Actions:
- Continue controller medications
- Use quick-relief (rescue) medication as directed
- Avoid triggers
- Monitor closely and contact healthcare provider if not improving
- Follow your child's Asthma Action Plan
Red Zone: Medical Alert (Below 50% of personal best)
What it means: Severe airway narrowing. This is a medical emergency.
Symptoms may include: Severe difficulty breathing, inability to speak in full sentences, blue lips or fingernails, extreme anxiety.
Actions:
- Use quick-relief medication immediately
- Contact your healthcare provider or emergency services right away
- If the child cannot talk, walk, or appears confused, call emergency services (911 or local emergency number) immediately
- Go to the nearest emergency room if symptoms do not improve quickly
When to Measure Peak Flow
Measurement frequency depends on asthma severity and control:
Daily Monitoring
- Children with moderate to severe asthma
- When establishing baseline or personal best
- During periods of poor asthma control
- Typically taken in the morning and evening at the same times
As Needed Monitoring
- When asthma symptoms appear or worsen
- Before and after using quick-relief medication
- During illness (cold, flu, respiratory infection)
- When exposed to known triggers
- Before physical activity if exercise-induced asthma is present
Periodic Monitoring
- Children with well-controlled mild asthma may check once or twice weekly
- At each medical appointment for asthma
Precautions and Important Safety Information
Device Precautions
- Peak flow meters are designed for single-patient use to prevent cross-infection
- Do not share the device between different children without proper disinfection and disposable mouthpieces
- Check the device before each use for damage, cracks, or foreign objects
- Ensure the indicator moves freely and returns to zero
- Replace the meter every 2-3 years with regular use, or as recommended by the manufacturer
Usage Precautions
- If the child becomes dizzy or lightheaded during testing, stop and rest before trying again
- Do not use peak flow readings as the only measure of asthma control - also monitor symptoms and activity limitations
- Readings can be effort-dependent - ensure proper technique for accurate results
- Dirt or mucus in the meter can affect accuracy
- Peak flow is in the red zone
- Quick-relief medication does not improve breathing
- The child has severe difficulty breathing
- Lips or fingernails turn blue or gray
- The child cannot speak in full sentences
- The child appears confused or extremely anxious
Storage Precautions
- Do not store in damp, humid, or extremely hot locations
- Keep away from direct sunlight
- Store in a clean, dry place
- Keep in the provided case when not in use
- Keep away from dust and pollutants
Cleaning and Maintenance
Regular Cleaning (Weekly)
During Illness
If the child has a cold, flu, or respiratory infection, clean the peak flow meter after every use to prevent reinfection.
Disinfection (Healthcare Settings)
For multi-patient use in healthcare settings, follow manufacturer-specific disinfection protocols. Use disposable mouthpieces and clean thoroughly between patients.
- Immerse digital meters completely in water (clean external surfaces only)
- Use boiling water
- Place in dishwasher (unless manufacturer specifies it is dishwasher-safe)
- Use harsh chemicals, alcohol-based cleaners on certain models, or abrasive materials
- Disassemble the internal mechanism
Maintenance Tips
- Check that the indicator moves freely and returns to zero before each use
- Replace batteries in digital models as needed
- Inspect for cracks, damage, or wear regularly
- Keep the instruction manual for reference
- Replace the device according to manufacturer recommendations (typically every 2-3 years)
Frequently Asked Questions
Q: At what age can children start using a peak flow meter?
A: Most children can use a peak flow meter effectively starting around age 4-5 years. However, the ability varies by child. Some children may be able to use it younger with practice and instruction.
Q: How often should my child use the peak flow meter?
A: This depends on asthma severity. Children with moderate to severe asthma may need daily monitoring (morning and evening). Those with well-controlled asthma might check once or twice weekly or only when symptoms occur. Follow your healthcare provider's recommendations.
Q: Should I take readings before or after medication?
A: Be consistent. Many healthcare providers recommend taking baseline readings before medication. You may also take readings after rescue medication to see if it is working. Always follow your child's Asthma Action Plan.
Q: What if the three readings are very different?
A: The three attempts should be close to each other. If they vary widely, the child may not be performing the technique correctly. Take a break, review proper technique, and try again.
Q: Can my child use the peak flow meter at school?
A: Yes. Many schools allow children to keep peak flow meters with the school nurse or in the classroom as part of their Asthma Action Plan. Provide the school with a copy of the action plan and proper instructions.
Q: Do I need a prescription to buy a peak flow meter?
A: In most countries, peak flow meters can be purchased without a prescription from pharmacies or medical supply stores. However, insurance coverage may require a prescription.
Q: Why is my child's peak flow lower in the morning?
A: Peak flow naturally varies throughout the day and is often lowest in the early morning. This is normal. Tracking both morning and evening readings helps identify patterns.
Q: What if my child's readings don't match the predicted values for their age and height?
A: Predicted values are averages. What matters most is your child's personal best and how current readings compare to it. Every child is different.
Q: Can siblings share a peak flow meter?
A: It is not recommended due to infection risk. If sharing is necessary, use disposable mouthpieces for each child and clean the device thoroughly between uses.
Q: How do I know if the meter is accurate?
A: Bring the meter to medical appointments and compare readings with clinical measurements. If readings seem inconsistent or the device is damaged, replace it.
Asthma Action Plan
A peak flow meter is most effective when used as part of a written Asthma Action Plan developed with your child's healthcare provider. This plan should include:
- Your child's personal best peak flow number
- Specific green, yellow, and red zone ranges
- Daily controller medications
- Instructions for quick-relief medication use in each zone
- When to contact the healthcare provider
- Emergency contact information
- Known asthma triggers to avoid
Share copies of the Asthma Action Plan with your child's school, daycare, coaches, and other caregivers.
Additional Considerations
For Healthcare Professionals
- Demonstrate proper technique at each visit and observe the child's technique
- Help families establish realistic personal best values
- Customize zone thresholds based on individual patient needs
- Review peak flow diary at each appointment
- Ensure families understand when to seek emergency care
For Parents and Caregivers
- Keep a written diary of peak flow readings along with symptoms and medication use
- Look for patterns that might indicate triggers
- Teach older children to take their own readings and interpret results
- Never adjust medications without consulting your healthcare provider
- Bring the peak flow diary to all medical appointments
Special Situations
Exercise-Induced Asthma: Take peak flow readings before and after physical activity to assess exercise impact.
During Travel: Always bring the peak flow meter, medications, and Asthma Action Plan when traveling.
Change in Environment: Monitor more closely during seasons or locations where asthma may worsen.
Where to Obtain Peak Flow Meters
Peak flow meters are available from:
- Pharmacies and drugstores
- Medical supply stores
- Online medical equipment retailers
- Healthcare provider offices (some provide them to patients)
Prices typically range from $20-50 for manual meters and $50-100 for digital meters. Check with your health insurance provider regarding coverage.
Key Takeaways
- Peak flow meters measure how fast air can be expelled from the lungs
- They provide early warning of asthma flare-ups, often before symptoms appear
- Regular monitoring helps track asthma control and guides treatment decisions
- Personal best values are more important than population averages
- Green, yellow, and red zones help determine appropriate actions
- Proper technique is essential for accurate readings
- Clean the device regularly and replace every 2-3 years
- Always use peak flow meters as part of a comprehensive Asthma Action Plan
- Seek emergency care if readings are in the red zone or symptoms are severe
Medical Disclaimer
The information provided in this guide is for educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Peak flow meters are monitoring tools and should be used under the guidance of a qualified healthcare provider. Always consult your child's pediatrician, allergist, or pulmonologist for personalized medical advice regarding asthma management.
Never delay seeking medical attention or disregard professional medical advice based on information from this guide. In case of medical emergencies, including severe breathing difficulty, call emergency services immediately.
Individual medical conditions vary, and asthma management plans should be customized to each child's specific needs. This guide provides general information and may not apply to every situation.
Content checked and reviewed by a qualified pediatrician.
Suggested Resources: For more detailed information, consult official guidelines from the National Asthma Education and Prevention Program (NAEPP), Global Initiative for Asthma (GINA), American Academy of Pediatrics, or your country's national respiratory or pediatric associations. Manufacturer instruction manuals provide device-specific information.
Labels: Asthma-Care, Respiratory-System