A small device with great importance Presented by : Dr. Jalal Mohsin Uddin DTCD, FCPS (Pulmonology) Presented by : Dr. Jalal Mohsin Uddin DTCD, FCPS (Pulmonology)

What is Peak Flow Meter ? A peak flow meter is an inexpensive, portable, handheld device for those with asthma that is used to measure how well air moves out of their lungs. The peak flow meter works by measuring how fast air comes out of the lungs when person exhale forcefully after inhaling fully. This measure is called a "peak expiratory flow," or "PEF.“ Keeping track of PEF, is one way patient can know if his symptoms of asthma are in control or worsening.

It is important to know that peak flow meter only measures the amount of airflow out of the large airways of the lungs. Changes in airflow caused by the small airways (which also occur with asthma) will not be detected by a peak flow meter. Small airway disease (SAD), defined by a reduction in forced expiratory flow at 25-75% of the pulmonary volume (FEF25-75).

The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) is a person's maximum speed of expiration. Normal expected value depends on a patient's sex, age and height. The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) is a person's maximum speed of expiration. Normal expected value depends on a patient's sex, age and height.

Definition of PEFR : The peak expiratory flow rate (PEFR, also known as a peak flow) is the maximal rate that a person can exhale during a short maximal expiratory effort after a full inspiration. In patients with asthma, the PEFR percent predicted correlates reasonably well with the percent predicted value for the forced expiratory volume in one second (FEV 1 ). The peak expiratory flow rate (PEFR, also known as a peak flow) is the maximal rate that a person can exhale during a short maximal expiratory effort after a full inspiration. In patients with asthma, the PEFR percent predicted correlates reasonably well with the percent predicted value for the forced expiratory volume in one second (FEV 1 ).

Peak expiratory flow is lowest in the early morning and highest in the afternoon. If patient wants to take the test only one time during the day, they should take it first in the morning, before using a bronchodilator medicine. Peak flow rate can be measured upon awakening and in the late afternoon or early evening. PEF varies throughout the day. In a person who does not have asthma, it may vary between 10% and 15%. In a person who has poorly controlled asthma, it may vary more than 20%. Peak expiratory flow is lowest in the early morning and highest in the afternoon. If patient wants to take the test only one time during the day, they should take it first in the morning, before using a bronchodilator medicine. Peak flow rate can be measured upon awakening and in the late afternoon or early evening. PEF varies throughout the day. In a person who does not have asthma, it may vary between 10% and 15%. In a person who has poorly controlled asthma, it may vary more than 20%.

Personal best : A person's personal best is his or her highest peak flow. This is the PEF, that will help the patient to find the correct asthma zones. The personal best is used in the self management plan that says what to do during a sudden asthma attacks. One can determine his personal best by taking PEF readings over 2 to 3 weeks when the asthma is under control. During these weeks, peak expiratory flows should be recorded at least twice daily. The personal best is usually reached in the afternoon or evening. Personal best measurements are never measured during an asthma attack. personal best is the highest reading you have over this period of time. A person's personal best is his or her highest peak flow. This is the PEF, that will help the patient to find the correct asthma zones. The personal best is used in the self management plan that says what to do during a sudden asthma attacks. One can determine his personal best by taking PEF readings over 2 to 3 weeks when the asthma is under control. During these weeks, peak expiratory flows should be recorded at least twice daily. The personal best is usually reached in the afternoon or evening. Personal best measurements are never measured during an asthma attack. personal best is the highest reading you have over this period of time.

Children need to have their personal best measurement checked about every 6 months to account for growth.

Peak flow chart of National Asthma Council of Australia : The peak flow chart is available as a two-page document in PDF format that one can download. The first page includes easy-to-follow instructions for entering the peak flow measurements. The second page is a chart that holds 8 weeks of measurements. The pages should be printed single-sided for easy reference. Print multiple copies of the second page if long- term monitoring is needed. The peak flow chart is available as a two-page document in PDF format that one can download. The first page includes easy-to-follow instructions for entering the peak flow measurements. The second page is a chart that holds 8 weeks of measurements. The pages should be printed single-sided for easy reference. Print multiple copies of the second page if long- term monitoring is needed.

The measurement of peak expiratory flow was pioneered by Martin Wright, who produced the first meter to measure lung function. The original design of instrument was introduced in the late 1950s, and the subsequent development of a more portable, lower cost version is the "Mini-Wright" peak flow meter.Martin Wright The measurement of peak expiratory flow was pioneered by Martin Wright, who produced the first meter to measure lung function. The original design of instrument was introduced in the late 1950s, and the subsequent development of a more portable, lower cost version is the "Mini-Wright" peak flow meter.Martin Wright

Who Should Use a Peak Flow Meter? People with moderate-to-severe asthma should have a peak flow meter at home. Even Peak flow meters are very helpful if a child have moderate to severe asthma and require daily asthma medications. Most children ages 6 and up should be able to use a peak flow meter. People with moderate-to-severe asthma should have a peak flow meter at home. Even Peak flow meters are very helpful if a child have moderate to severe asthma and require daily asthma medications. Most children ages 6 and up should be able to use a peak flow meter.

How to use peak flow meter? 1)Move the marker to the bottom of the numbered scale, and connect the mouthpiece to the peak flow meter (if it isn't already connected). 2)Stand up if you're able. 3)Take a deep breath, filling your lungs completely. 4)Place your lips tightly around the mouthpiece. Blow as hard and as fast as you can with a single breath. 5)Note the final position of the marker. This is your peak flow rate. 6)Follow the steps above then blow into the peak flow meter two more times. Record the highest reading of the three. 1)Move the marker to the bottom of the numbered scale, and connect the mouthpiece to the peak flow meter (if it isn't already connected). 2)Stand up if you're able. 3)Take a deep breath, filling your lungs completely. 4)Place your lips tightly around the mouthpiece. Blow as hard and as fast as you can with a single breath. 5)Note the final position of the marker. This is your peak flow rate. 6)Follow the steps above then blow into the peak flow meter two more times. Record the highest reading of the three.

Why it's done ? 1.To recognize early changes that may be signs of worsening asthma and thus preventing asthma attack. (Explanation : During an asthma attack, the muscles in the airways tighten and cause the airways to narrow. The peak flow meter alerts you to the tightening of the airways often hours or even days before,the patient have any asthma symptoms. By using own PEF with his/her asthma action plan, he/she will know when to take his/her rescue asthma inhaler or other asthma medicine. By following the steps in asthma action plan, patient may be able to stop the narrowing of the airways quickly and avoid a severe asthma emergency). 1.To recognize early changes that may be signs of worsening asthma and thus preventing asthma attack. (Explanation : During an asthma attack, the muscles in the airways tighten and cause the airways to narrow. The peak flow meter alerts you to the tightening of the airways often hours or even days before,the patient have any asthma symptoms. By using own PEF with his/her asthma action plan, he/she will know when to take his/her rescue asthma inhaler or other asthma medicine. By following the steps in asthma action plan, patient may be able to stop the narrowing of the airways quickly and avoid a severe asthma emergency).

2. Patient can learn what triggers their asthma. 3. It helps patient to decide whether their asthma action plan is working well. 4. It helps patient to decide when to add or adjust asthma medications. 5. The patient came to Know when to seek emergency care. 2. Patient can learn what triggers their asthma. 3. It helps patient to decide whether their asthma action plan is working well. 4. It helps patient to decide when to add or adjust asthma medications. 5. The patient came to Know when to seek emergency care.

Classification of Peak flow readings: Peak flow readings are often classified into 3 zones of measurement according to the American Lung Association; green, yellow, and red. Doctors and health practitioners can develop an asthma management plan based on the green-yellow-red zones. American Lung Association Peak flow readings are often classified into 3 zones of measurement according to the American Lung Association; green, yellow, and red. Doctors and health practitioners can develop an asthma management plan based on the green-yellow-red zones. American Lung Association

ZonesReadingDescription Green zone80 to 100 percent of the usual or normal peak flow readings are clear. A peak flow reading in the green zone indicates that the asthma is under good control. Yellow zone 50 to 79 percent of the usual or normal peak flow readings Indicates caution. It may mean respiratory airways are narrowing and additional medication may be required. Red zone Less than 50 percent of the usual or normal peak flow readings Indicates a medical emergency. Severe airway narrowing may be occurring and immediate action needs to be taken. This would usually involve contacting a doctor or hospital.medical emergency

Reversibility with PEF Take initial Peak Flow (PEF) measurement - best of 3 good blows. Give salbutamol through appropriate device. If mins since salbutamol, take 2nd PEF measurement Calculate percentage reversibility - Difference between 1st & 2nd PEF X 100 1st PEF measurement If less than 15%, consider other causes eg URTI; COPD; cardiac; anaemia; cystic fibrosis; TB; malignancy etc. Take initial Peak Flow (PEF) measurement - best of 3 good blows. Give salbutamol through appropriate device. If mins since salbutamol, take 2nd PEF measurement Calculate percentage reversibility - Difference between 1st & 2nd PEF X 100 1st PEF measurement If less than 15%, consider other causes eg URTI; COPD; cardiac; anaemia; cystic fibrosis; TB; malignancy etc.

How to take care of Peak Flow Meter? Most peak flow meters require weekly cleaning with warm water and a mild detergent.