About Asthma

What is Asthma?

Asthma is a chronic inflammatory disorder of the airways in which the bronchi are reversibly narrowed. It affects people of all ages and is a significant source of morbidity and mortality worldwide [1,2].

Asthma Information

Pathophysiology of asthma

Airway narrowing with impaired airflow is the main physiological event leading to the clinical symptoms of asthma [2,3]. This can be caused by several factors including:

• Bronchoconstriction – contraction of airway smooth muscle (bronchoconstriction) is the predominant mechanism of airway narrowing and can be largely reversed [2,3]. In an acute asthma exacerbation, bronchoconstriction occurs rapidly in response to a variety of stimuli such as allergen [3].
• Airway oedema – this is due to increased microvascular leakage in response to inflammatory mediators [2,3].
• Airway remodeling – this involves the activation of many structural cells and permanent changes in the airway that increase airflow obstruction, such as hypertrophy and hyperplasia of the smooth muscle and thickening of the sub-basement membrane. As a result, airflow limitation may only be partly reversible in some patients [2,3].

Airway hyperresponsiveness, an exaggerated bronchoconstrictor response to a variety of stimuli is a major characteristic abnormality of asthma [2,3]. The resultant airway narrowing leads to variable airflow limitation and intermittent symptoms and is partly reversible with therapy.

Asthma symptoms

Asthma is characterised by episodic symptoms and fluctuating levels of airway inflammation which may culminate in an asthma exacerbation. Symptoms of asthma include coughing, wheezing, shortness of breath and tightness in the chest.

Goal of asthma management

The goal of asthma management is to achieve and maintain overall asthma control, which includes current control (immediate and recent past) and the future risk of for example, exacerbations, instability, permanent impairment of lung function and the adverse effects of treatment [2].

Treatment options for asthma

Asthma treatment strategies should address acute airway inflammation, a key factor associated with loss of lung function in asthma patients.

Asthma treatments include the following:

• Controllers (anti-inflammatory agents) – these are the mainstay treatment for asthma and are used on a long-term basis to keep asthma under clinical control by reducing the underlying inflammation. Examples include inhaled corticosteroids (ICSs), long-acting β2-agonists (LABAs) in combination with ICSs, and leukotriene modifiers. ICS are the most effective controller therapy currently available [2]
• Relievers (bronchodilators) – used on an as-needed basis and act quickly to reverse bronchoconstriction and relieve symptoms. Examples include rapid-acting β2-agonists and inhaled anticholinergics [2].

Combination inhalers have been the mainstay for the treatment of asthma for a number of years. For adults with moderate to severe asthma inadequately controlled on ICS maintenance therapy alone, Global Initiative for Asthma (GINA) guidelines recommend the addition of a LABA or a leukotriene antagonist, such as the ICS/LABA combination budesonide/formoterol (Symbicort®) [2]. Read more about Symbicort in asthma.

References

1. Riccioni G, D'Orazio N, Di Ilio C, et al. Quality of Life and clinical symptoms in asthmatic subjects. J Asthma 2004;41:85-89.
2. Global Initiative for Asthma. Global strategy for asthma management and prevention - updated 2008. Available at: www.ginasthma.com. Last accessed 11 December 2009.
3. National Heart Lung and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. 2007.