Peak Flow Meter 101

Peak Flow Meter 101

A peak flow meter is a device that measures the speed of air blowing out of your lungs after a deep inhalation. In other words, it measures your ability to push air out of your lungs. It is for the monitoring, management and control of asthma or other respitory conditions. It takes measurements of peak expiratory flow rate (PEF or PEFR) and forced expiratory volume in one second (FEV1).

Peak flow meters can be categorized as mechanical and electronic. Most of peak flow meters are mechanical ones while electronic peak flow meters are now emerging into the market.

The essential part of a peak flow meter is its transduction system which transfers the input that a patient produces (the air one pushes out of the lungs) into a signal which can be measured. There are five most commonly used transduction systems: variable-orifice, fixed-orifice or venturi, stator/rotor, pneumotachographs and ultrasonic [1]. Mechanical peak flow meters are designed under different principles while most electronic peak flow meters are designed as a stator/rotor system.

A digital peak flow meter, such as the Microlife Electronic Peak Flow Monitor Model PF-100, normally “incorporates a removable micro medical digital volume transducer which consists of an acrylic tube with a freely rotating vane supported on jeweled bearings positioned between a fixed swirl plate and a cross bar. As air is passed through the transducer, a vortex is created by the swirl plate, which causes the low inertia vane to rotate. The rotation of the vane is detected by the interruption of an infrared beam which produces an electrical pulse train at the output of a phototransistor. The number of rotations is proportional to the volume of air passed through the turbine, and the rate of rotation is proportional to the flow rate. With flow rate and correspondent time, FEV1 can be calculated.”[2] Ferraris 345010 Piko-1 Electronic Peak Flow Meter is similar as Microlife PFM, but comes with a much smaller size. Piko-1 PFM is a truly pocket-size portable meter.

1. Stand or Sit straight.
2. Take a deep breath.
3. Cover your mouthpiece tightly with your lips.
4. Blow as hard and as fast as you can to get the reading. Be careful to avoid spitting into the mask.
5. It is recommended to perform this three times in a row for an accurate measurement.

Measurements with a peak flow meter can assist you and your doctor to monitor your asthma or respiratory condition. These measurements are important to record and analyze your breathing abilities over time so that your doctor can prescribe the correct medicine to keep your asthma in control.

First, you need to find out what is your optimal reading based on your age, sex and weight. Although reference readings can be found, your optimal PEF is the essential index for your future asthma management. This reading is normally taken when your asthma is well controlled. Your management plan will be based on this number and you doctor will recommend a medication to take when your asthma worsens.

If there is not much difference between your daily reading and the reference, your asthma is well controlled; you and your doctor may try to lower the level of your medicines. Otherwise, a peak flow meter may demonstrate that you may need to change the way you are using your medicines.

Your doctor may make a customized management plan for you and describe how to use the plan. Normally, a 'traffic light system' is adopted which uses green, yellow and red to indicate the severity of your asthma. When a reading falls in a zone with specific color, you need to take corresponding action. For example, when your reading falls into the red zone, you may have to follow your doctor's recommendations for your worsening asthma, such as taking steroid tablets or seeking urgent medical attention.

If you use an old fashion peak flow meter, you need to record your daily readings in a chart. However, if you use a state-of-the-art digital peak flow meter, such as Microlife Peak Flow Meter, the device records your measurements into its embedded digital storage. Combined with the software package (sold separately), you and your doctor will be able to analyze and manage your readings easily on the computer.