It is important to use objective lung function indicators to evaluate and monitor the severity of asthma. Pulmonary function measurements are important as a method to diagnose asthma, analyze the severity of the disease, and guide the use of medication. Peak flow rate can know the maximum expiratory flow rate amount, which is the most common simple pulmonary function measurement done by asthma patients. By insisting on measuring your peak flow rate regularly every day and keeping an asthma diary or chart, you can grasp the pattern of asthma attacks and adjust your medication according to the changes in peak flow rate, which can greatly reduce the number of attacks and the degree of attacks. Especially in the early stage of deterioration, it is difficult for the patient to detect it (you cannot judge the severity of asthma by your own feeling), if you can tell your doctor about the peak flow rate record, he will understand your condition. The patient and the doctor can also use this information to compare the effects of various treatments. If an asthmatic’s peak flow rate readings keep dropping and do not return to normal, the asthma can strike at any time. Additional treatment given early in the early stages of an asthma attack can stop the attack.
Peak flow velocity values as a measure for diagnosing and monitoring pulmonary function in asthma are similar to relevant measurements made in other chronic diseases, just as blood pressure measurements with a sphygmomanometer are used to diagnose and monitor hypertension, and blood glucose measurements with test strips or digital display meters are used to diagnose and monitor diabetes, showing the significance of PEF measurements in asthma.
Recording peak flow rate values at home is recommended for those who have
For children over 5 years of age, in addition to measuring PEF at each visit of the child, daily home monitoring of PEF using a simple peak flow rate meter is recommended for moderate to severe cases.
Instructions for use of the peak velocimeter
The Peak Velocity Meter is an instrument used to measure maximum expiratory flow, mainly for asthma patients to measure maximum expiratory flow values at home under the guidance of a physician. You can also ask your doctor to check frequently that the maximum expiratory flow values are recorded correctly and that the expected values do not need to be corrected. If you find that the maximum expiratory flow value is moving in the direction of an exacerbation, contact your doctor immediately for prompt treatment.
How to use the Peak Flowmeter
1. Put the thick end of the transparent mouthpiece with the round interface of the peak velocity meter and set it tightly.
2, the peak velocity meter red vernier pointer gently dial to the lowest part of the scale.
3. Inhale as much as possible, wrap your lips around the mouthpiece, pay attention to the lips around not to leak air, and then in the shortest possible time, exhale all the air at once with force.
4. At this point, please record the value of the red cursor pointer at the scale, this value is your highest expiratory flow value.
5. If you want to repeat the test, please note: before each test, you should dial the red vernier pointer to the lowest part of the scale.
6. Each test can be performed three times, select the highest one expiratory flow value (PEFR) along with the date and time of the test, recorded in the test record sheet.
7. After each test, please keep the peak velocity meter in a safe place for re-use.
The setting method of peak expiratory flow rate partition
Part of the peak velocity meter design green-yellow, red-yellow pointer, in order to allow you to directly observe the current expiratory flow rate value area, so that you can timely treatment.
The method of setting is as follows.
1, Work with your doctor to determine an optimal value for your PEF.
2. Set the yellow-green pointer at 80% of your PEF optimal value.
3, Set the red and yellow cursors at 60% of your PEF optimum. Measurement, when the red cursor pointer stays between the yellow-green and red-yellow pointer of the yellow area, indicating an alert state; higher than the green range, indicating a more normal; if lower than the red range, indicating that the situation is no longer good, should promptly seek medical attention.
Main technical indicators.
Scale: 60-850L/min; in the range of 200-600L/min, error plus or minus 10%, coefficient of variation: CV less than or equal to 5%.
Caution
1.The peak velocity meter is not sterilized.
2.The peak velocity meter is limited to exclusive use.
3, peak velocity meter should be careful not to fall, often check whether the damage, the red vernier pointer action is normal; if the peak velocity meter is found to have abnormal phenomena, should stop using.
Cleaning and disinfection methods
Peak tachometer should be cleaned frequently to keep clean. Cleaning, with a clean container, holding an appropriate amount of room temperature (about 20 ° C) of water (to vertical into the peak tachometer can be submerged in half as appropriate), 1-2 drops of detergent, hold the peak tachometer at the mouth containing the device, gently shaking in the cleaning solution to clean 2-3 minutes, replace the water, wash according to the above method, remove the remaining water in the peak tachometer gently shake dry, placed in the vent natural drying to completely Dry for the next use. Peak velocity meter can not be placed in the sun, can not be put into the oven and fire baking.
Contraindications.
Patients with severe asthma and in respiratory distress should not use this product.
Maximum expiratory flow value continuous recording
1. Fill in your name, fill in the expected value
2. Record the date at the top of each cell, this chart allows you to record 31 days
3. Record the time of your daily measurement, record 1-2 times a day
4. Put the maximum expiratory flow value measured, and draw a “●” at the corresponding place on the table
5. Draw a line between each point of the measured value each day, this is your maximum expiratory flow continuous record
Personal best value of peak expiratory flow rate (PEFR) (use it as a criterion for determining whether you have an attack).
Asthma control for more than two weeks without any asthma symptoms; patient feeling good about himself; highest PEFR value blown by careful measurement of PEFR for two weeks.
The daily measured PEFR value should not be less than 80% of the personal best value or the inter-day variability should not be greater than 20%. Once this occurs further treatment is required or a hospital visit is required.
Formula for calculating the inter-day variability.
PEFR daytime maximum value – PEFR daytime minimum value
Intraday variability = ——— ———- × 100%
1/2 (PEFR daytime maximum + PEFR daytime minimum)
Types of peak flow rate meters
There are generally two types of peak flow velocimeters, mechanical and electronic. Mechanical peak flowmeters are increasingly accepted by families of children with asthma because of their convenience and practicality and cheap price. Recently, a new generation of electronic peak flowmeters (“asthma companion”) has also started to enter the lives of children with asthma. Compared with the traditional mechanical type, it can measure not only the maximum peak expiratory flow rate (PEF), but also the important index of pulmonary ventilation function parameters: the first second forceful expiratory volume (FEV1). The electronic peak flow velocity meter uses pressure differential electronic sensing elements, digital display results, more accurate and repeatable; small size, light weight, can store 96 times the test value, generally more than 5 years old children can use.
Peak expiratory flow rate (PEF) measurement
The only thing the child needs to do to perform a PEF measurement is to blow a short burst of maximum airflow. We can figuratively inspire the child to blow like a candle on a birthday cake, but with a faster and stronger exhalation. This is usually done well in children over the age of 5. However, no matter how old the child is, it is important to train at the beginning because only with the correct technique can we get a true and objective picture of the changes in lung function.
The best time to measure PEF
The PEF should be measured twice a day, after waking up in the morning and before going to bed at night, i.e. the first thing you do early in the morning and the last thing you do at night before going to bed. Each measurement is taken three times and its optimal value is recorded, preferably plotted as a curve, which is more visual. For children with inhaled β2-agonists, it is best to measure before and 10-15 minutes after the drug and record both values; the significance of the data measured after the drug is that it can confirm whether it is effective for inhaled drugs and can also be used to calculate the variability of PEF. In the case that PEF can only be measured once a day, it is best to fix it every morning after waking up, and fix it before or after inhalation, so that the measured results are comparable and can be detected once changes occur.
Normal values of maximum peak flow rate (PEF)
It is usually compared to the expected value (i.e., normal value). The expected value of PEF is different for each individual and is generally related to age, height, weight, etc., and in children also to gender. How to calculate its expected value? One is to check the chart method; second is to calculate according to the following formula: PEF expected value (L/min): 5.29 x height (cm) for boys – 427.1; 4.94 x height (cm) for girls – 399.8.
Q: I would like to ask what the optimal peak flow rate value should be for my little girl. I bought a peak flow rate meter, and I’m not sure if the test results will be accurate?] Age: 5 weeks and 2 months (birth date January 21, 2004), gender: female, height/weight: 1.11M/16KG, what should the individual peak flow velocity values be for the yellow, red and green zones, and what should the corresponding peak flow values be for each? Thanks!
A: For a 5-year-old girl (height 1.11M), the PEF is usually in the range of 155-165L/min (150 according to the simple formula). However, due to the large normal range of peak flow rate values, it is usually recommended that each asthma patient should find her own personal best value. By personal best, I mean the highest peak flow rate value you (your child) can achieve when your asthma is well controlled and monitored continuously for two weeks. During this two-week period, the highest flow rate is measured every day, three times in the morning and three times in the evening, and the highest of the three times is the highest peak flow rate.
Green zone: 80-100% of the personal best flow rate value, indicating that the asthma is largely controlled and that preventive medication can be used as usual.
Yellow zone: 60-80% of the personal best flow rate, indicating a possible asthma attack and the need for additional bronchodilators; or that your condition is not under control and your doctor needs to adjust your treatment plan.
Red Zone: Below 60% of your personal best flow rate, indicating a medical warning to inhale a short-acting bronchodilator (e.g., Ventolin, Asthma) and take it to the hospital immediately.
Q: Height is 111CM, measured at Children’s Hospital. My peak flow rate for the past two days is 160 in the morning and 170 in the evening.
A.
PEFR daytime highest value – PEFR daytime lowest value
Inter-day variability = ——— ———- ×100%
1/2 (PEFR daytime maximum + PEFR daytime minimum)
The above formula is helpful for you in this question.
The indicators of normal lung function are: FEV1 or PEF large at 80% or more of the individual’s best expected value, or PEF diurnal wave
(or diurnal variability) is less than 20%. Your child’s height is 1.11 meters and the normal expected value is 155-165, so the measured values are within the reference range for both morning and evening.
In addition, your child’s current PEF diurnal variability is about 6% according to the above formula.
So, congratulations, your child’s lung function is now normal. You should continue the inhaled hormone therapy, keep the asthma diary, and test the PEF value every day. Good luck to your child to control his asthma soon!