In this blog we will look into the peak flow meter, and its use and management of bronchial asthma.
A peak flow meter is a very good simple device that a patient with bronchial asthma may use for management of bronchial asthma to check the variability of airway responsiveness.
There is a predicted peak flow based on age, height, sex, and race which one may need to know. Obtain the predicted peak flow calculation through your healthcare provider or you can search on line for the formula. It is a general number for a guideline and may have some variations but it will be a good gauge to understand a person’s peak flow.
Generally, the variation is less than 20%. In patients with mild, intermittent asthma the peak flow is generally more than 80% of the predicted and the variation should be less than 20%.
The patient with asthma symptoms or experiencing acute on chronic asthmatic bronchitis may experience an increase in peak flow variation during the acute phase and should stabilize to the baseline. Generally, with mild intermittent asthma, the peak flow variation is less than 20%.
With mild persistent asthma, patients will have an increase in severity of asthma where they tend to have symptoms more than two times at night in a month and about twice a week. Although the predicted peak flow is greater than 80%, they may experience a peak flow variability of 20-30%.
For example, if a 35-year-old gentleman with a height of 5 feet 6 inches has a peak flow of 512 liters per minute, the 20% variation would be a peak flow range between 400 to 600 liters per minute. If it goes less than 400 liters per minute, it should be considered increased variability.
Also, there are some peak flows which are color coded with a green zone, a yellow zone and a red zone. This makes it a little simpler for people to follow. As long as they stay within the green zone, they should be okay; but once they change to the yellow zone, this may suggest increase bronchospasm, increase mucus formation or start of early infection, etc. One needs to contact the healthcare provider as it could be an early sign of asthma flare up.
The peak flow can help in asthma exacerbation prevention by monitoring very closely before it becomes worse. Patients with chronic asthma will find it helpful.
If the patient has bronchial asthma but also has associated chronic pulmonary disease, the variation in the peak flow may not be as much especially if one is a smoker.
In patients with moderate persistent asthma, the peak flow variability may be more than 30%.
This would be someone who has daily symptoms and uses a rescue inhaler at least twice a week or more and has a one-time nighttime symptom in a month. Also, patients with severe persistent asthma may have daily symptoms and frequent nighttime symptoms. The peak flow generally varies less than 60% of the predicted, and has increase variability to more than 30% in a day from a baseline.
As asthma improves with treatment, the variability may change and should become less than 20% with decrease in the need of rescue inhaler. Monitoring acute infections, avoiding drugs that produce bronchospasm, eliminating foods that increase mucus formation, and avoiding external factors that increase bronchospasm in conjunction with the standard treatment with inhalers and medication may further help chronic bronchial asthma treatment and management with monitoring of one’s own peak flow and keeping a log on a regular basis. This log may also help provide a chance for the healthcare professional to review the change and make adjustments in medications as needed and the person to better understand their own underlying asthma and its variability. A simple peak flow meter can give a lot of insight into one’s own bronchospasm and its management.
For more information on peakflow you can visit the following website.
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