Asthma is a chronic inflammatory disease of the airways. Caused by environmental and genetic factors, it is characterized by variable and recurring symptoms, reversible airflow obstruction and bronchospasm.
Asthma is clinically classified according to:
1. Frequency of symptoms
2. Forced expiratory volume in 1 second (FEV1)
3. Peak expiratory flow rate
It can also be classified as:
1. Atopic (extrinsic)
2. Non-atopic (intrinsic)
Brittle asthma is a term used to describe two rare phenotypes of asthma - Type 1, which is characterized by sustained, chronic variability of PEFR and Type 2 which is distinguished by sudden severe exacerbations.
Also referred as acute asthma exacerbation, the symptoms are dyspnea, wheezing and tightening of the chest. The colour of skin and nails appear blue due to lack of oxygen.
Status asthmaticus is considered a medical emergency as it is a life-threatening episode of airway obstruction and does not respond to standard treatments of bronchodilators and steroids. Characterised by smooth muscle hypertrophy and basement membrane thickening, this acute asthma exacerbation can cause complications like cardiac and/or respiratory arrest.
Exercise induced asthma
It is a medical condition caused by sustained aerobatic activities.
Occupational asthma can be attributed to a particular working environment or condition.
An asthmatic patient shows the following signs:
2. Shortness of breath
3. Chest tightness and
The symptoms can get worse at night or early morning, cold air or in response to exercise. The patient can also suffer from Gastro-esophageal reflux disease caused due to increased lung pressures, promoting bronchoconstriction, and through chronic aspiration and sleep disorder.
Asthma is caused by environmental and genetic factors.
Many environmental risk factors associated with asthma are:
1. Exposure to air pollutants and endotoxins
2. Low air quality, from traffic pollution or high ozone levels
4. Maternal tobacco smoking during and after pregnancy
5. Psychological stress or strong emotional expression
6. Use of antibiotics in early stage of life and use of beta blocker medications in those susceptible
7. Indoor exposure to volatile organic compounds
8. Changes in weather (most often cold weather)
9. Respiratory infections, such as common cold
10. Dust, house mites, animal dander, cockroach allergens and molds
Genetic factors are another major cause of asthma. Over 100 genes, especially those associated with the immune system, or to modulating inflammation can cause asthma among susceptible.
Currently there is no precise way to diagnose asthma. Pattern of the symptoms and response to therapy over a period of time are helpful in diagnosis of asthmatic patients. In the latest guidelines from the US National Asthma Education and Prevention Program (NAEPP) recommend spirometry, to measure the airflow in the airway at the time of initial diagnosis.
Other recommend test include Tests may include arterial blood gas, blood tests to measure eosinophil count and IgE, Chest x-ray, Lung function tests and peak flow measurements.
Though there is no effective way to prevent asthma, yet limiting exposure to air pollutants, smoking can help reduce risk.
Depending on the severity of attack, the treatment can be divided into to categories:
1. Quick relief medication acts fast in case a patient shows acute symptoms.
Beta2-adrenoceptor agonists (SABA), like salbutamol (albuterol USAN) are the first line of treatment. Anticholinergic medications, when administered in combination with SABA provide additional benefits. Selective adrenergic agonists also have a similar efficacy to SABA, but are usually not recommended.
2. Long-term control medications is recommended to a patient to prevent further asthma exacerbation.
Glucocorticoids are the most effective treatment available for long term control of asthma. Long acting beta-adrenoceptor agonists (LABA) also helps prevent symptoms but be inhaled only with steroid drug. Leukotriene antagonists, mast cell stabilizers are other non-preferred alternatives to glucocorticoids.
Compiled by: Liji Varghese