Asthma: Types, Causes, Symptoms, Diagnosis, and Treatment

It is a long-term inflammatory disease of the airways of the lungs. Asthma affects an estimated 25,00,000 Indians every year. Adult women have a 30% greater prevalence of asthma than men. Asthma attacks may occur a few times a day or a few times per week.

Depending on the person, asthma symptoms may become worse at night or with exercise. Frequency and severity vary from person to person

Asthma: Types

Asthma could be of the following types −

• Allergic Asthma (Extrinsic Asthma) – The symptoms are induced by a hyperimmune response to the inhalation of a specific allergen. Type I (Immediate) hypersensitivity reaction is the basis of the IgE.

• Non-Allergic Asthma (Intrinsic Asthma) – This type is triggered by the presence of irritants in the air that are not related to allergies. These irritants stimulate parasympathetic nerve fibers in the airways causing bronchoconstriction and inflammation.

• Mixed Asthma – The combination of both allergic and non-allergic asthma. This is the most common form of asthma.

• Cough Variant Asthma – It is characterized by one symptom, a persistent dry cough. It does not have the classic symptoms of asthma such as wheezing and shortness of breath.

• Exercise-Induced Asthma – This variant of asthma affects the person during or after physical activity.

• Nocturnal Asthma – In nocturnal asthma symptoms gets worse at night. Those who suffer from nocturnal asthma can also experience symptoms any time of day.

• Occupational Asthma – It is induced by workplace triggers such as textiles, farming, and woodworking.

Asthma: Causes

Asthma is caused by a combination of complex and incompletely understood environmental and genetic interactions. These influence both its severity and its responsiveness to treatment.

• Allergen inhalation: Animal, House dust, Cockroaches, and Pollens

• Air pollutants: Exhaust fumes, Perfumes, Oxidants, and Cigarette smoke

• Viral upper respiratory infection

• Sinusitis

• Exercise and cold dry air

• Stress

• Drugs: Aspirin, NSAIDs, and β- adrenergic blockers

• Occupational exposures: Metal salts, Wood, vegetable dust, Industrial chemicals, and plastics

• Food additives

• Gastroesophageal reflux disease

Asthma: Symptoms

Patients with Asthma present with the symptoms such as wheezing, dyspnoea, cough, and chest tightness. Their expiration may be prolonged and secretions may be white, thick, tenacious, gelatinous mucus.

Classification of Asthma based on clinical severity/symptoms −

• Mild Intermittent Asthma − Daytime symptoms, twice a week. Night time symptoms, twice a month. Asymptomatic, no long-term medications, only short-term for quick relief.

• Mild Persistent Asthma − Daytime symptoms, more than twice a week. Night time symptoms, more than twice a month. Asymptomatic, abnormal pulmonary tests, daily one medication-daily, quick short relief.

• Moderate Persistent Asthma − Every day and every night symptoms. Two medications daily and quick relief daily basis. Limited physical activity because attacks are frequent.

• Severe Persistent Asthma − Continuous daytime, frequent night time symptoms. Two medications daily and quick relief. Very limited physical activity.

Following complications occur due to chronicity and severity −

• Disturbed sleeping pattern due to anxiety, dyspnoea as evidenced by frequent awakening, the prolonged onset of sleep, lethargy, fatigue, and irritability.

• Risk for infection related to decreased pulmonary function, possible corticosteroid therapy, and lack of knowledge regarding signs and symptoms of infection and preventive measures.

• Rib fracture

• Pneumothorax

• Atelectasis

• Pneumonia

• Status asthmaticus

Asthma: Risk Factors

The major risk factors include −

• Having a blood relative with asthma, such as a parent or sibling

• Having another allergic condition, such as atopic dermatitis which causes red, itchy skin, or hay fever, which causes a runny nose, congestion, and itchy eyes

• Being overweight

• Being a smoker

• Exposure to smoke

Asthma: Diagnosis

Asthma is diagnosed based on several factors, including a detailed medical history, physical examination, symptoms, overall health, and test results.

• Medical History and Physical Examination − The first step in diagnosing asthma is to look for signs of asthma or allergies. Wheezing (high-pitched whistling sounds when breathing out) and a runny nose or swollen nasal passages, and allergic skin conditions.

• Lung function test − The most common lung function test used to diagnose asthma is Spirometry. It is often used to determine the amount of airway obstruction. The spirometer measures the amount (volume) and speed (flow) of air that can be inhaled and exhaled, giving an indication of how well the lungs are performing.

In addition, the following tests can also be performed to diagnose Asthma −

• Peak expiratory flow rate

• Chest X-ray

• ABG or oximetry

• Allergy skin testing

• Blood level of eosinophils and IgE

Asthma: Treatment

Drug therapy depends on the frequency and severity of attacks.

• Bronchodilators − They are often considered rescue inhalers

• Anti-inflammatory drugs

• Corticosteroids

• Long acting β2: Adrenergic agonists

• Theophylline

• Bronchodilators (Sympathomimetics) − Bronchodilators bind to the receptors in airway smooth muscle thus causing bronchodilation. For example, Albuterol, Salbutamol and Terbutaline.

• Anticholinergic agents − Anticholinergic agents decrease or block the actions of acetylcholine on parasympathetic nervous system receptors on smooth muscle cells. Acetylcholine is a neurotransmitter that contracts the smooth muscle. For example, Ipratropium, Aclidinium.

• Corticosteroids − The inhaled corticosteroids reduce airway inflammation. It suppresses βadrenergic receptor action on leukocytes. For example, Beclomethasone, Flunisolide, Triamcinolone.

• Biologic Response Modifiers (Monoclonal Antibodies) − The effect of Biologic Response Modifiers is decreased frequency of allergen-induced asthma. The monoclonal antibody binds to IgE and interferes with mast cell binding. This prevents mast cell degranulation and the release of inflammatory mediators. For example, Omalizumab.

• Leukotriene Receptor Antagonists − The effect of leukotriene receptor antagonists is the prevention of allergen-induced bronchoconstriction by preventing histamine release. For example, Montelukast and Zafirlukast.

• Mast Cell Stabilizers − Prevents bronchoconstriction and inflammation. Mast cell stabilizers antagonize mast cell degranulation thereby preventing the release of histamine and other mediators of allergic reaction. For example, Cromolyn and Nedocromil.

• Methylxanthine Derivatives − The mechanism of action for methylxanthine derivatives is bronchodilation. For example, Theophylline.

Asthma: Prevention

The following precautionary measures can be taken to prevent the occurrence of Asthma −

• Identify and avoid asthma triggers.

• Identify and treat attacks early and monitor breathing.

• Other measures include dust free house. Intake of selective types of food.

• Avoid exposure to extreme cold conditions.

• Get vaccinated for influenza and pneumonia

• Eating fish oil, rich in omega-3 fatty acids, could help reduce the risk by nearly 70%.

• Vitamin D may influence asthma by impacting antioxidant or immune-related pathways

Conclusion

Asthma is a condition in which airways narrow and swell and produce extra mucus, which leads to breathing difficulty and triggers coughing, wheezing, and shortness of breath. It is a long-term inflammatory disease of the airways of the lungs. Frequency and severity vary from person to person.

Asthma presents as Wheezing, Dyspnoea, Cough, and Chest tightness. It is caused by a combination of complex and incompletely understood environmental and genetic interactions. Diagnosis is based on physical examination and lung function test. Treatment depends on the frequency and severity of attacks.