Asthma

Asthma is a common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.  Symptoms include wheezing, coughing, chest tightness, and shortness of breath.

 Prevalence

15% of the children population suffers from asthma compared to 2-5% of adults with a 2:1 male/ female preponderance in childhood due to decreased bronchi diameter in males.

Etiology

Asthma can be classified as atopic (extrinsic) or non-atopic (intrinsic), based on whether symptoms are precipitated by allergens (atopic) or not (non-atopic).

• Allergic/Atopic asthma is also defined as early onset asthma- this is diagnosed in children who are prone to allergies and who usually suffer from allergic diseases such as rhinitis, urticaria and eczema.  This group of patients has positive skin tests, has a raised IgE and has a positive response to the provocation tests with aeroallergens.
• Idiosyncratic/ Non-atopic asthma, also known as late onset asthma is diagnosed in individuals who don’t suffer from allergic diseases, have negative skin tests and a normal IgE. These patients become symptomatic when they have upper respiratory infections with symptoms lasting days to months.

Symptoms

Common symptoms of asthma include wheezing, shortness of breath, chest tightness and coughing. Symptoms are often worse at night or in the early morning, or in response to exercise or cold air. Some people with asthma only rarely experience symptoms, usually in response to triggers, whereas others may have marked persistent airflow obstruction. 

It is always important to identify triggers of asthma in each individual

Some of the known triggers are:

• Allergens-pollen
• Pharmacological stimuli- aspirin, nsaids, B-adrenergic blockers
• Environment pollution- NO₂, ozone, carbondioxide
• Occupational- metal, salts
• Infections-respiratory viruses
• Exercise- inhalation of cold dry air can cause thermally induced hyperemia and microvascular engorgement
• Emotional stress 

Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate. It can be classified as either intermittent, mild persistent, moderate persistent and acute

Intermittent asthma is diagnosed when there is not more than

• 1 or 2 episodes of daytime coughing and/or wheezing
• Less than 1 night time cough and/or wheeze per month
• No recent, within the last year, admission to hospital for asthma.
• When the PEFR is more than 80% predicted between attacks.

Mild persistent asthma

• 2-4 episodes of daytime coughing and/or wheezing
• 2-4 episodes of night time coughing and/or wheezing per month
• Recent admission to hospital which was related to asthma exacerbation
• PEFR >80% predicted between episodes

Moderate persistent asthma

• More than 4 episodes of daytime coughing and/or wheezing
• More than 4 episodes of night time coughing and/or wheezing per month
• Recent admission to hospital which was related to asthma exacerbation
• PEFR >60% but less than 40% of  predicted between episodes 

Diagnosis

There is currently not a precise physiologic, immunologic, or histologic test for diagnosing asthma. The diagnosis is usually made based on the clinical picture, the pattern of symptoms (airways obstruction and hyper responsiveness) and/or response to therapy (partial or complete reversibility) over time. 

Management of intermittent, mild persistent and moderate persistent asthma

The most effective treatment for asthma is identifying triggers, such as cigarette smoke, pets, aspirin and eliminating exposure to them. If trigger avoidance is insufficient, medical treatment is recommended.  Medical treatments used depend on the severity of illness and the frequency of symptoms. Specific medications for asthma are broadly classified into fast-acting and long-acting categories.

Bronchodilators, such as salbutamol, are fast acting agents, they are recommended for short-term relief of symptoms. They are used in patents who suffer from intermittent asthma where no other medication is needed. If mild persistent disease is present (more than two attacks a week), low-dose inhaled glucocorticoids or alternatively, an oral leukotriene antagonist or a mast cell stabilizer is recommended in combination with a bronchodilator.

Patients suffering from daily attacks need an ever increasing dose of inhaled glucocorticoids to control their symptoms or those suffering from an acute attack of asthma need urgent medical attention with hospital admission as soon as possible. They are treated with immediate oxygen, salbutamol nebulizer and intravenous corticosteroids.

Conclusion

Asthma has a good prognosis, especially for children diagnosed with mild disease. 54% of children diagnosed with asthma during childhood no longer carry the diagnosis after a decade.