Assessment of asthma severity by peak flow

This is an automatically translated article.

The article was professionally consulted by Dr. Phan Dinh Thuy Tien - General Internal Medicine - Department of Examination & Internal Medicine - Vinmec Nha Trang International General Hospital.
Asthma is a chronic disease. Severe asthma, if not detected and treated, can be life-threatening.

1. What is Asthma?

Asthma or bronchial asthma is a chronic disease that causes inflammation of the airways, causing constriction and mucus secretion reactions.
In asthmatic patients, the bronchial tree system is more easily inflamed and sensitive than usual. Patients are prone to shortness of breath due to airflow obstruction or bronchospasm that causes coughing, wheezing, and chest tightness.
The severity of the asthma attack depends on the degree of obstruction of the airways. If the patient has only mild shortness of breath and little wheezing, the asthma attack is defined as mild. On the contrary, when the patient has severe shortness of breath, has a whistling sound, or the whole body is pale and lethargic, this is a malignant asthma attack, potentially life-threatening if not treated promptly.
Apart from the asthma attack, the patient leads a completely normal life, without any suspicious symptoms. Accordingly, the assessment of asthma is necessary to plan long-term treatment, both preventing attacks and controlling attacks effectively.

2. What is the assessment of asthma severity by peak flow meter?

Measuring the degree of airway obstruction is a direct way of determining the severity of an asthma attack.
Instruments to measure the degree of airway obstruction are commonly used tools to measure respiratory function in laboratories. In practice, however, there is a simpler, more convenient handheld device for home use such as a peak flow meter.
The principle of operation of the peak flowmeter is to measure the flow of air out of the large airways of the lungs.

3. Who and when should the severity of an asthma attack be assessed by peak expiratory flow (PEF)?

A peak flow meter is a must-have device for people with frequent episodes of uncontrollable asthma or moderate to severe asthma attacks who require tight daily control. combination of many drug groups.
In addition, this tool will also be necessary for people who have recently been diagnosed with bronchial asthma or diagnosed with asthma in children. For children from 3 years of age and older, children have the cognitive ability to actively measure their own peak flow when having a seizure to notify parents or caregivers for timely treatment.
Thanks to peak flow measurement, caregivers or patients themselves can early identify the following problems so that they can promptly use the right reliever medication, preventing symptoms from progressing too quickly beyond control or prevent possible complications
Note that peak flow should not be measured when a patient is in a severe or malignant asthma attack. Because what needs to be done at this time is to give maximum emergency to the patient, regardless of the peak flow parameters. The right time to choose is in the morning, when the body feels the most healthy and before taking the medication to prevent attacks. And it is recommended to measure more in the afternoon, because usually the afternoon peak flowmeter is the highest of the day.

4. How is peak flow rate assessment of asthma severity performed?

Before measuring, it is necessary to check that the indicator bar of the instrument returns to the correct zero line. Patient's position is comfortable, sitting or standing upright for maximum breathing and consistent with the same posture at all times of measurement. continuity.
How to measure:
4.1. Inhale a maximum of 4.2. Close the tube The patient needs to know how to properly hold the tip of the peak flowmeter tube so that it fits snugly, does not leak gas and also does not let the lips and tongue cover the measuring tube to reduce the obtained results.
4.3. Blow out the patient uses the full force of respiration to blow out the entire volume of air in the chest very strongly and quickly in just one blow.
4.4. Read and record parameters Read and record the readings obtained on the peak flowmeter. Repeat up to two more similar measurements and select the best obtained result. Repeated measurement more than three times will not further improve results because respiratory muscle strength is reduced.
It is recommended to measure PEF twice daily, morning and afternoon. PEF is normally lowest in the morning and highest in the afternoon, varying with each patient, environment, activity intensity...
If peak flow is measured during an attack, the first series of measurements should be performed in the same manner as above. . After that, the patient was given a reliever medication that dilates the bronchi. Waiting for 10 to 20 minutes for the drug to take effect is to conduct a second series of measurements for comparison. Select the ratio between the peak flow before bronchodilator and after the highest of the measurements for evaluation.

5. How is the severity of an asthma attack determined by a peak flow meter?

In order to assess the severity of an asthma attack by a peak flow meter accurately and objectively, it is necessary to avoid factors that affect the measurement results, including: The patient's ability to cooperate, the way full mouth and exhalation as well as the accuracy of the measuring device.
For children, pay attention to choosing the background level of peak flow that is appropriate for the child's gender, age and height.
For adults, this parameter is taken when you feel the best, there are no acute diseases in other organs because it can also affect the ability to breathe.

In short, a peak flow meter is a must-have tool in every family with asthmatics. With convenient, simple to use, relatively accurate results, it is a useful tool to support initial asthma control at home as well as monitor the improvement of respiratory function in the long term. .

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