Asthma is the most common disease of the respiratory tract. It is an inflammatory disease of the lungs. Mainly the airways are affected as a result of a series of inflammatory reactions. Scientifically, asthma is defined on the basis of a series of clinical symptoms and is diagnosed on the same basis. Asthma has many levels of severity. Most severe and acute form is called as status asthmaticus.
Other forms of asthma are as under;
Childhood allergic asthma
This form of asthma starts its early manifestations in early childhood. It usually presents before the age of 12. Causes of childhood onset asthma is allergy in almost all cases. This allergy is the result of atopy.
Adult onset asthma
This is another form of severe asthma that does not appear in the childhood but comes later in adulthood. 34 percent of this type of asthma is due to atopy. The atopic asthma manifests as a result of any allergen for which genes are encoded.
Pathological mechanism of asthma
Conducting part of the respiratory tract is the target area of asthma. Chronic exposure to allergens or the stimuli causes repeated response of airways of respiratory tract. As a result of irritation, inflammatory substances are released from the local tissue causing local reaction. There is increased mucous production and mechanical narrowing of airways along with inflammatory substances that makes it difficult to breath. All these events result in difficult breathing, wheezing of chest and respiratory distress in the patient of asthma.
Diagnosis of asthma
Most of the times, there is a clinical diagnosis of asthma. But to know the extent and cause of asthma, certain other tests may be required. The most common method is spirometry. This is not a diagnostic test but helps in supporting the diagnosis. Peak expiratory flow is measured through spirometry.
Peak expiratory flow
- After a full inspiration, the maximum flow that can be possible by a person through forceful expiration is called as peak expiratory flow. Other than spirometers, it can also be measure by the specially designed peak flow meters.
- Technique of measuring peak expiratory flow matters a lot. After full inspiration, patient has to put his mouth on the device and expire with his full efforts using his chest and abdominal muscles. The value obtained is the peak expiratory flow of the patient.
- The values of peak expiratory flow are correlated with the symptoms of asthma as shown in many studies done on spirometry and asthma. Usually, there is a decrease in peak flow values in severe cases of asthma. This is the reason, it is used as the only supporting method for diagnosis of asthma.
Asthma peak flow chart
Asthma peak flow chart is maintained for the same reason. It is used to correlate the symptoms with the values obtained at different intervals and different situations. Hospitalized patients are specially assessed for the PEF1 values to know if the patient’s symptoms are relieving as a result of medications or not.