Asthma - Symptoms, Causes, Types, Diagnosis and Treatment

Asthma definition

Asthma is a chronic inflammatory respiratory condition that is characterized by symptoms of intermittent dyspnea (shortness of breath), cough, and wheezing. Distinguishing asthma from other respiratory illnesses can be challenging because of the non-specific nature of these symptoms. Asthma that develops in childhood involves a complex interaction between genetic and environmental factors. A confirmed diagnosis of asthma depends on constant respiratory symptoms and detection of expiratory obstruction of the airway recorded on spirometry. Physicians prioritize symptomatic control and preventing future progression through tailored treatment by considering the severity and potential risk in a systematic and step wise approach. Pulmonologists can successfully treat and manage asthma.

Asthma meaning

The actual term asthma is derived from the Greek word “aazein” which means to exhale with an open mouth, to pant. The word asthma appeared for the first time in the Iliad with the meaning of short drawn breath, but the Corpus Hippocraticum was the earliest term from where the medical term was found.

Prevalence of asthma

Asthma prevalence worldwide 

With increasing prevalence rates in many countries, asthma is a substantial global health problem. As per World Health Organization (WHO) reports, 30 crore people have asthma, and two lakh fifty-five thousand (255000) people died due to asthma in the year 2005.

Prevalence of asthma in India

Asthma prevalence in India is estimated to be 3% (3 crores) with a prevalence of 2.4 percent in adults aged more than 15 years and between 4 and 20 percent in children. About 57,000 deaths attributed to asthma were reported in the year 2004. It has become one of the leading causes of morbidity and mortality in rural India and is predicted to increase in the coming year.

Types of asthma

Asthma is no longer thought of as a single disease, and it is categorized into different types based on the factors causing it. Following are some of the types of bronchial asthma: 

• Allergic asthma - Also called atopic asthma, it is the onset or development of asthma symptoms due to allergic reactions caused by inhaled allergens. Allergens include pollen, dust, animal dander, and mold. These allergens are harmless substances that are mistaken for harmful and attacked by the body’s immune system. The immune response leads to symptoms of asthma.
• Non allergic asthma - Also called non-atopic asthma. This type of asthma is not triggered by allergens such as pollen or dust, it often develops later in life and is triggered by factors that are not allergens such as household chemicals, certain medications, infections such as cold and flu, outdoor air pollution, and tobacco smoking. 
• Seasonal asthma - This type of asthma develops only at certain times of year such as during hay fever season or when the weather is cold. 
• Occupational asthma or work-related asthma - Symptoms of asthma that occur due to exposure to certain chemicals or irritants at the workplace are known as occupational asthma.
• Childhood onset asthma - Symptoms of asthma that develop during childhood are known as childhood asthma. This is the most common type of asthma. 
• Adult-onset asthma - Symptoms of asthma that develop or present for the first time during adulthood, with the age varying from 12 to 65 years are termed adult-onset asthma. 
• Eosinophilic asthma - High levels of eosinophils in the airway cause eosinophilic asthma, it is a severe type of asthma. 
• Exercise induced asthma - This type of asthma occurs when the airways tighten, and airflow gets obstructed during or after exercise.
  

Asthma Phenotypes and Endotypes

Asthma is a heterogeneous disease and since early childhood, depending on the phenotypes and endotypes many classifications have been proposed. A deep understanding of the endotype and phenotype of the patient gives an idea regarding a tailored therapeutic approach. 

• Phenotypes include clinical features of asthma-like age of onset, triggers, comorbidities, and response to treatment over a period of time. 
• Endotypes are difficult to define, these include immunopathological mechanisms of the disease. 

Asthma phenotypes classification 

Five major phenotypes in adult patients include 

• Mild to early onset allergic disease
• Moderate early onset allergic disease
• Late onset eosinophilic non allergic disease
• Severe early onset eosinophilic allergic disease
• Late onset non allergic neutrophilic severe asthma with fixed airflow obstruction.

Asthma endotypes classification

Four major endotypes of asthma include:

• Early onset mild allergic asthma
• Moderate to severe allergic remodeling asthma
• Late onset allergic non eosinophilic asthma and 
• Late onset allergic eosinophilic asthma.

Asthma symptoms

Symptoms of asthma occur intermittently and last for about a few hours to days. These symptoms resolve when the triggers are removed or with the administration of medications. 

Common asthma signs and symptoms include

• Shortness of breath (SOB)
• Cough
• Tightness of chest
• Decrease in peak flow meter 
• Waking up at night due to a worsening of cough

Severe asthma symptoms

Symptoms of severe asthma are often persistent, and these symptoms are observed at least once a day. Below are some of the asthma attack symptoms observed in patients:

• Breathlessness which is persistent and continuous
• Heavy feeling in the chest
• Wheezing
• Severe cough
• Difficulty in speaking
• Allergic responses to pollen and dust
• Extreme sensitivity to scents and smell
• Blue lips or fingers
• Rapid heart rate 
• Drowsiness
• Confusion
• Dizziness 

Asthma causes

The exact cause of asthma is not known, and the causes may vary from person to person, however, asthma can develop when the body’s defense system reacts strongly to a new substance in the lungs. Asthma usually develops during childhood (called childhood asthma); however, some people don’t show signs of asthma until adulthood (adulthood asthma). Many factors like allergens in the environment, viral infections, and family history work together to develop asthma. 

Several factors have been linked to the development of asthma although it is difficult to identify the actual cause. Below are some of the causes of bronchial asthma: 

• Family history: Asthma is more likely to develop when there is a family history of asthma, that is if one of the family members, like a father or a sibling, has asthma.
• Allergy conditions: Patients with allergic conditions such as eczema and rhinitis are more prone to develop asthma. 
• Lifestyle factors: A sedentary lifestyle in urban areas increases the prevalence of asthma.
• Development of the lungs can be affected by certain events in childhood such as low birth weight, prematurity, exposure to smoke, and air pollution. When the lungs are not developed fully, they do not function effectively and increase the prevalence of asthma.
• Being overweight or obese in children or adults also causes asthma.
• Exposure to environmental allergens and irritants including outdoor and indoor, air pollution, dust, mites, molds, and exposure to chemicals in occupational areas also increases the risk for the development of asthma. 
  

Asthma risk factors

Asthma is believed to result from the interaction between genetic and environmental factors. Several risk factors contribute to asthma, and these factors of bronchial asthma are described below:

• Atopy: It is a genetic tendency to develop allergic diseases like allergic rhinitis, and asthma.
• Tobacco: Smoking is a known risk factor for asthma. It is more difficult to control asthma in asthmatic smokers than non-smokers with asthma. 
• Pollution: Exposure to outdoor and indoor air pollution remains a significant risk factor. 
• Obesity: Many studies indicated that asthma is more likely to develop in obese patients
• Occupational risk factors: Exposure to chemicals or pollutants at workplaces is a potential risk factor for asthmatic patients. 
• Microbes: Asthmatic patients are susceptible to viral and bacterial infections.
• Stress: Recent studies suggested that there are some potential mechanisms that underly the association between chronic psychosocial stress and asthma genetics.
  

Complications of asthma

The complications of bronchial asthma include complications that are disease related and adverse effects of glucocorticoids and endotracheal intubation. Some of the common complications associated with asthma are as follows: 

• Decline in lung function: Airway remodeling (structural airway changes and inflammation) in asthma results in declined lung function. 
• Osteoporosis: Patients with asthma may develop Osteoporosis, a condition where bone becomes weak and brittle.
• Infections: Asthma increases the risk of infection due to damaged airways. 
• Hypertension (high blood pressure): Chronic inflammation in asthma can contribute to high blood pressure over a prolonged period.
• Diabetes: Asthma can increase the risk of type 1 and type 2 diabetes due to systemic inflammation
• Sleep disorder: Respiratory disturbances during sleep are common. Severe coughing and wheezing in asthma cause frequent arousals from sleep at nighttime. 
• Obstructive sleep apnea: Asthmatic patients are more prone to develop obstructive sleep apnea. 
• Mood disorder: Asthma increases the risk of mood disorders like anxiety and depression.
• Cardiac arrest: Inflammation in asthma over time may build up plaque which leads to cardiac arrest, heart attack, etc. 
• Glaucoma: Inhaling steroids increases the risk of glaucoma which is a condition where the optic nerve that connects the eye to the brain gets damaged. 
• Respiratory failure: Asthma over time causes respiratory failure. 
• Pneumothorax: In patients with asthma, bronchospasm increases pleural pressure and causes pneumothorax which is a life-threatening condition. Pneumothorax is the collection of air outside the lungs within the pleural cavity).
  

Asthma diagnosis

Early diagnosis and treatment of asthma is necessary to prevent the progression of asthma. General physicians and pulmonologists develop a definitive diagnosis. Following are some of the tests to diagnose asthma: 

• Medical history
• Physical examination 
• Laboratory testing 
• Complete blood cell (CBC) count
• Serum alpha 1 antitrypsin level
• Seum IgE 
• Imaging tests
• Chest radiographs 
• Computed tomography (CT)
• Pulmonary function test
• Spirometry
• Bronchoprovocation testing 
• Peak flow meter
• Exhaled nitic oxide
  

Asthma treatment

Treatment of asthma depends on the age, severity of the disease, and how the body responds to the specific drug.

Nonpharmacological treatment of asthma

Drug therapy is important in the treatment of asthma and in keeping the disease under control. But some non-pharmacological interventions are also suggested in the treatment of asthma. Nonpharmacological management of asthma includes: 

• Regular exercise
• Maintaining healthy body weight 
• Proper diet 
• Stopping smoking
• Relaxation and breathing techniques 
  

Pharmacological treatment of asthma 

Treatment mainly focuses on providing education, regular assessment of symptoms, providing access to fast acting bronchodilators and controller medications. The following are the treatment options available: 

• Quick relief asthma medication 
• Inhaled short acting beta 2 agonist
• Oral corticosteroids
• Short acting anticholinergics

• Long term asthma control medications 
• Corticosteroids
• Biologic medications
• Leukotriene modifiers
• Inhaled mast cell stabilizers
• Inhaled long-acting bronchodilators
• Allergy shots.
  

Treatment of asthma in pregnancy

Below are some of the measures that can be followed for asthma treatment during pregnancy:

• Continued use of preventer inhalers that are prescribed during pregnancy
• Avoiding smoke
• Regular exercise and a healthy diet 
• Avoiding allergens that trigger asthma such as pet fur and pollen
  

Types of asthma inhalers

Inhalers are devices that deliver or incorporate medications in a fine mist right into the lungs. These are considered as the first line treatments for asthma and can be used to treat other respiratory conditions. 

Following are some of the common types of inhalers:

• Metered dose inhaler – It is the most common type of inhaler, and this is held in front or put into the mouth when the medicine is released in puffs. A chemical is used to push forward the medicine into the lungs. 
• Nebulizer – In this type of inhaler medicine is released as fine liquid mist, and the mouthpiece delivers the medicine. A nebulizer is often recommended to patients who cannot use metered dose inhalers. 
• Dry powder inhaler – This inhaler are used by children and adults. Medicines such as dry powder is released when patients breathe in at the mouthpiece.
  

Asthma prevention

The exact cause of asthma is unknown; therefore, it may not be possible to prevent asthma, but the severity and further progression of the disease can be prevented.

Further progression of the disease severity can be prevented by adopting a stepwise approach to disease management and strategies to prevent risk factors. Essential parts of asthma management include patient education, monitoring the symptoms to prevent the progression of the disease, controlling factors that trigger asthma, managing co-morbid conditions, and following a stepwise treatment approach.

The severity of asthma varies and differs among individuals and different age groups therefore it is essential to monitor the effectiveness of asthma control to suggest the required adjustments or modifications in a treatment plan. 

Below are some of the measures to prevent asthma from further progression and severity:

• Encouraging patients to build a healthy lifestyle by educating them about the potential triggers of asthma. 
• Recognizing early warning signs of an asthma attack and seeking medical attention when necessary.
• Emphasizing the importance of medication adherence to prevent further progression of disease severity.
• Individuals with active asthma are recommended for routine follow up visits every six months. During these follow-ups physicians assess lung function, exacerbations, the efficacy of medications, quality of life, and patient satisfaction.

Difference between Asthma and COPD

Asthma vs COPD

Both asthma and chronic obstructive pulmonary disease (COPD) are respiratory diseases that affect breathing, but they have some key differences. The following are the parameters that differentiate asthma and chronic obstructive pulmonary disease (COPD):

Difference between asthma and bronchitis

Asthma vs bronchitis

Asthma and bronchitis both are respiratory conditions that present cough as their symptom, but they have some key differences. Below are some of the factors that differentiate between asthma and bronchitis.