Asthma: Causes, Triggers, Diagnosis, Treatment & Prevention

Last Updated on May 5, 2023 by Shabnam Sengupta

According to World Health Organization (WHO), about 262 million people were affected by Asthma in 2019. It has been observed that asthma often remains under-diagnosed, particularly in lower income countries. There is no cure of Asthma, however, awareness of the disease and its proper management can enable people with asthma to live a good and active life.

Introduction

Asthma is an inflammatory disorder that causes excessive sensitivity of the airways against a triggering factor. This leads to inflammation and narrowing of airways causing difficulty in breathing.

A healthy individual inhales air, which passes from the airways and trachea to reach the lungs for blood purification. These airways have smooth muscles lining in their walls along with cilia that produce mucus. Cilia protects dust from entering the airways.

The severity of the disease can range from mild to very severe. In the initial stages, the patient has infrequent asthma attacks, whereas in the later stages, the quality of life is hampered severely.

During an asthma attack, these smooth muscles are inflamed and enlarged, and the cilia over-secretes mucus leading to blockage in the airways.

The reasons behind an asthma attack are:

1. Tightening of the muscles that line the airways
2. Increased mucus secretion 
3. Inflammation of airways

Symptoms

The most common clinical symptoms are as follows:

1. Shortness of breath 
2. Tightness in chest 
3. Wheezing sound during breathing 
4. Cough
5. Difficulty in sleep 
6. Frequent respiratory infections 
7. Anxiousness 
8. Difficulty in talking , exercising 
9. Attacks during a particular time (nocturnal)or job (occupational) or activity (exercise induced)

Causes

There is no definitive cause of asthma but available research papers have shown that both environmental factors and genetic factors contribute to the disease development.

1. Genetic factors: Various genes have been linked to increased susceptibility towards the risk factors of Asthma.
2. Environmental factors: Many substances, called allergens, are present in the environment that cause inflammation of the airways. When the mucosa  comes in contact with the allergen, various chemicals like interleukins are secreted from the mucosa leading to inflammation.

The most common triggers/environmental allergens have been listed below:

1. Pollen 
2. Dust 
3. Fungal spores 
4. Pet fur
5. Cold air 
6. Smoke 
7. Exercise 
8. Medicines like aspirin, ibuprofen, beta blockers 
9. Air pollutants 
10. Emotional stress 
11. Gastroesophageal reflux disease 
12. Preservatives added in the food 
13. Food allergens like prawns, peanuts 

Risk Factors

1. Obesity: It increases the risk of getting the disease.
2. Hygiene hypothesis: The hypothesis says that when children are overprotected from the external dust and other allergens, it leads to hypersensitivity of the mucosal wall of the respiratory pathway when they are exposed to them later in their lives.
3. History of other allergic diseases: There is a greater risk of developing asthma for a person if they have a history of other allergic diseases like eczema and rhinitis as these diseases can trigger their immune system.
4. Viral infections: Positive history of infection of Respiratory Syncytial Virus (RSV) has shown to lead to asthma later in life.

Types

1. Childhood Asthma: These are asthma attacks that occur at a very young age and are usually linked to either genetic or allergic histories.
2. Adolescent Asthma: The symptoms start appearing when the child hits puberty and is usually due to history of viral illness.
3. Occupational Asthma: The symptoms are linked to a particular occupation like dye industry, petrochemical industry, rubber industry, etc., which exposes the person to some specific allergen triggering the inflammation.
4. Seasonal Asthma: The symptoms flare up only at a particular time of the year like in spring when there is pollen circulating in the air. In such cases pollen may be a trigger for an asthma attack 
5. Exercise induced Asthma: Normally, a person breathes air which is cleared from dust in the respiratory tract before reaching the lungs. However, during exercise, people tend to breathe faster and a lot of times through the mouth. This results in lack of filtration of the air entering the lungs.
6. Aspirin induced Asthma: In this type, the attacks are precipitated whenever the person consumes medicines like aspirin or ibuprofen.
7. Nocturnal Asthma: In this type, the attacks occur and/or worsens during the nights.
8. Cough variant Asthma: In this type, there is no mucus secretion. There is prolonged and persistent dry cough, which if not treated can lead to full fledged asthma.

Diagnosis

The following tests are done in order to make the diagnosis:

1. Family history: It’s taken in order to know the prevalence of asthma in the family. 
2. Allergic history: History for any other hypersensitivity present in the individual. 
3. Physical examination: It is done to diagnose asthma by listening to lungs for wheezing, examining the nose and throat for swelling and checking for barrel-shaped chest, which is common among kids suffering from childhood asthma. 
4. Patch test: In this, triggering allergens are identified by putting various allergens in contact with the skin and checking the sensitivity against each.
5. Chest X-ray: In the cases of severe asthmatic attacks, a doctor may suggest a chest X-ray. Chest X-rays also help in diagnosing lung or heart diseases among asthma patients who exhibit their symptoms.
6. Pulmonary function test: Various lung capacities like inhalation and exhalation are checked, which gets affected in the cases of asthma.
7. Blood tests: To check the levels of immunoglobulin E, which increases in the cases of hypersensitivity diseases like asthma. 

Treatment

The treatment of Asthma depends on whether we are treating an attack or designing a long term treatment:

1. Treatment for acute attack:

Short Acting Beta Agonists (SABA) like salbutamol can be given under the supervision of the doctors. Steroids like Beclomethasone are prescribed to decrease the inflammation on an immediate basis. (Both of these medications are given in the form of inhalers)

2. Long term preventative treatment:

Medicines which prevent the inflammatory chemical release like Mast cell stabilisers, Leukotriene antagonists, etc. can be administered. Long term bronchodilators are also prescribed. (These are usually given via oral route)

Prevention

The following ways can help to minimise attacks and to identify them early on:

1. Avoid triggering allergens.
2. Follow the asthma medications regimen seriously.
3. Get vaccinated with the latest flu shots.
4. Avoid smoking
5. Maintain a healthy weight
6. Have a good diet
7. In case of exercise induced asthma, avoid rigorous working out.
8. In case of occupational asthma, try to change the profession.
9. Monitor your breathing rate and sound.

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