Diagnostic methods for diseases of the respiratory system are aimed at studying the ventilation capacity of the lungs and are needed to determine the parameters of the respiratory function. Peak flowmetry is a mandatory procedure for chronic obstructive pathologies, which include bronchial asthma and bronchitis . The advantages of the method include ease of research and the ability to take measurements at home using portable instruments.
For what diseases is it prescribed
The ability of the bronchi to pass enough air to ensure respiratory function gives an idea of the width of their lumen. Peak expiratory flow (PEF) displays the parameters of bronchial patency, on the basis of which a conclusion is made about pulmonary ventilation. For asthmatics, a peak flow meter is a necessary device, since a change in indicators towards the worsening indicates an approaching attack. Indications for peak flowmetry:
- Bronchial asthma.
- Chronic obstructive bronchitis.
- Pulmonary emphysema.
- Respiratory failure of unknown etiology.
Measurement of the expiratory flow rate allows for differential diagnosis of bronchial asthma with bronchitis or heart disease. Determination of PSV using this technique has a number of advantages over complex procedures – spirography and spirometry, which require stationary equipment and certain skills in using the device.
The main objectives of the procedure
The speed of manipulation and the ability to control independently at home made peak flowmetry an irreplaceable diagnostic tool. The target category for it is asthmatics and patients with chronic bronchitis, but for other people, the definition of PSV can be useful. The scope of application of peak flowmetry in medicine is extensive:
- This procedure is the main means of monitoring the health of asthmatics, and measurements taken at home can predict a deterioration in well-being and avoid the development of asthmatic status.
- Examination of a pregnant woman will show insufficient ventilation function of the lungs and indirectly indicate the likelihood of developing fetal hypoxia . The study is carried out under the supervision of a physician, since forced exhalation can lead to a deterioration in well-being during pregnancy.
- At the stage of examination of pulmonary patients, peak flowmetry is prescribed in order to identify the reversibility of obstructive changes in the bronchi.
- The procedure for determining PSV helps to find the dependence of the development of bronchospasm in the presence of an allergenic irritant.
- By measuring the peak expiratory flow rate, exposure to occupational and industrial hazards can be established.
- During a routine examination, the method allows you to make a conclusion about the degree of risk of developing bronchial asthma.
- In the course of choosing the optimal therapy regimen for the treatment of bronchial asthma using peak flowmetry, it is possible to determine the effectiveness of drug treatment or to adjust their dosage.
Peak flowmetry is carried out to study the respiratory function in healthy adults , for example, to assess the endurance of athletes in preparation for participating in competitions and those whose professional activities make high demands on health. Controlling PSV indicators is a good means of preventing respiratory diseases.
Peak flow meter device
The peak expiratory flow apparatus is a rather old invention. The basic principle of operation of the device is based on the pressure of an air stream that passes through a narrow valve and shifts the needle to a certain value. The first peak flow meter appeared in 1958 , was large, bulky and extremely inconvenient to use. Subsequent improvement made it possible to create a portable device, as well as to simplify the procedure for working with it. Modern devices are compact in size, designed to conduct a study of respiratory function in patients of different ages and do not require special handling skills. There are several types of peak flow meters for stationary and home use:
- In the diagnostic centers, professional devices are installed for examining patients, which are connected to monitors, after which information is processed through a computer.
- Peak flow meters for home use easily fit into a pocket, and peak flow results are displayed immediately on a scale printed on the body of the device. For ease of decoding, digital designations are located in three zones – red, yellow and green, which correspond to the hazard level.
Peak flow meters for an adult and a child differ in a set of possible values. The baby device contains a scale with a small scatter of digital indicators from 35 to 350 l / min. On an adult peak flow meter, the maximum value is 850 l / min and the minimum is 60 l / min and this device is suitable for use by teenagers. Universal devices for determining PSV with an extended scale range allow measurements in a person of any age category. It is possible to perform peak flow measurement with one device for all family members, changing replaceable tips and performing simple processing. Anyone can use the device after consulting a doctor or reading the instructions .
Do you need preparation
The results of PSV measurements depend on the physical and mental state of a person. To correctly measure, you should adhere to the standard algorithm for conducting peak flowmetry:
- The optimal measurement time is considered early morning immediately after getting up, and the control test is done 12 hours later.
- Before starting the study, you need to rest for half an hour, otherwise the device will show distorted values.
- The procedure is performed on an empty stomach or 2 hours after a meal.
- An important rule applies to taking medications. Measurements should be taken before starting medication.
- In preparation, you should get rid of embarrassing clothing.
- The most reliable results are obtained in a standing position, when the lungs are able to open up as much as possible, but sitting peak flowmetry is also possible if the patient’s well-being requires it.
It is important to hold the device correctly . It should be horizontal and the results of the previous test should be reset. Subject to simple conditions, the data obtained helps to track the required parameters, which are assessed by analyzing the measurement diary.
Process of conducting
The technique of performing peak flowmetry is described in detail in the annotation for the device for home use, and before diagnostics at a medical institution, employees describe in detail the procedure. A well- performed manipulation and proper preparation for it are the key to obtaining reliable results that help stabilize a person’s condition with respiratory pathologies.
The peak flow measurement process takes a few minutes:
- After taking the desired position and preparing the device to start working, take a deep breath through your mouth.
- The nostrils must be clamped with the free hand.
- Exhale with your mouth, pressing the peak flow meter tightly to your lips.
- After a minute of rest, the procedure is repeated twice more, and then the highest value obtained is entered into the self-control diary.
Keeping a measurement schedule is necessary in the presence of respiratory pathology, especially in people with obstructive syndrome. With the help of peak flowmetry, you can identify normal individual indicators, find the difference between the extreme points of PSV, determine at what moments there is a strong deviation from the boundaries of your own norm. Peak flow diary helps the doctor to choose the best means to treat and analyze the precipitating factors.
The boundaries of the norm of volumetric parameters of the lungs fluctuate depending on the sex, age, height and weight of a person, his psycho-emotional state and individual characteristics. With the help of regular peak flowmetry, it is possible to obtain calculated data, which are then processed according to the developed formulas. There are tables with approximate indicators of the norm for children and adults, which should be guided by.
For adults, the main calculations are carried out based on age criteria. Normally, the PSV in a healthy person is from 314 to 550 l / min, depending on age. The deviation from normal values in percent will be shown by the device. According to the marked scale, the values will be located in three zones. Finding a test result in the green sector assumes that the PSV is more than 80% of the desired value, in the yellow one – from 60% to 80%, and in the red one – below 90% of the norm.
For children and adolescents, there is a different scale of normal values. The calculations are carried out depending on the height, and the range of values is from 130 to 290 l / min. Deviations will also be visible on the peak flow meter scale, and when using an adult device, special tables will help make calculations.