Cigarette smoking is the largest environmental risk factor for mortality and explains the higher prevalence of COPD in older age and among males. However, the prevalence of COPD among women is increasing.
Respiratory Area
Chronic obstructive pulmonary disease (COPD)
Chronic obstructive pulmonary disease (COPD) is defined as a disease characterised by chronic respiratory symptoms due to airway abnormalities that cause persistent, often progressive airway obstruction. The chronic limitation of pulmonary airflow characteristic of COPD is partially or completely non-reversible. COPD is an important cause of mortality worldwide and represents a major public health problem.
COPD is the result of interactions between genetic and environmental factors that occur throughout an individual's life and can damage the lungs.
Several specific occupational exposures, including coal particles from mines, have been proposed as risk factors for COPD.
The most relevant (though rare) genetic risk factor for COPD identified to date is mutations leading to α-1 antitrypsin deficiency.
Other factors that may contribute to bronchial obstruction are inhalation of toxic particles and gases from household and environmental air pollution.
Respiratory infections, especially those of viral origin, are important causes of COPD flare-ups.
The three most common symptoms of COPD are cough, sputum and exertional dyspnoea. The development of exertional dyspnoea is often described as increased effort required to breathe, air hunger or choking. Many patients present with these symptoms for months or years before seeking medical attention. Although the development of bronchial obstruction is a gradual process, many patients attribute the onset of the disease to an acute event or flare-up.
As COPD worsens, the main feature becomes exertional dyspnoea with progressive reduction in the ability to perform occupational and non-occupational activities. In more advanced stages, dyspnoea also appears during the performance of daily activities.
Relapses are a predominant feature of the natural history of COPD. They are commonly defined as episodes of increased dyspnoea and coughing with changes in the quantity and characteristics of sputum.
The increased frequency of exacerbations is accompanied by worsening bronchial obstruction.
The approach to a patient with COPD should include a thorough history and a complete physical examination. The history should include quantification of the degree of dyspnoea and information on the occurrence of dyspnoea as a result of normal or special activities.
The examination that confirms the presence of airflow limitation, and thus the diagnosis of COPD, is spirometry.
Chronic obstructive pulmonary disease (COPD) is usually easy to differentiate from asthma, since the symptoms show less variability, do not regress completely and show less (or no) reversibility. Approximately 10% of COPD patients present with aspects of asthma.
Asthma
Asthma is a disease characterised by airway obstruction that varies markedly both spontaneously and after treatment. Asthmatics develop a particular form of airway inflammation that makes the airways more responsive to a wider range of stimuli than non-asthmatics leading to excessive bronchoconstriction resulting in reduced airflow and symptoms characterised by wheezing, dyspnoea and coughing. The reduction in airway calibre is usually reversible but in some patients with chronic asthma there may be a condition of irreversible bronchial obstruction.
Asthma is one of the most common chronic diseases and currently affects more than 300 million people worldwide. Asthma can occur at any age with a peak at 3 years of age; in childhood the male sex is twice as represented as the female sex, but in adults this ratio normalises.
Asthma is a heterogeneous disease in which genetic and environmental factors intersect. Several risk factors predisposing to asthma have been identified. These must be distinguished from triggering factors, which are environmental factors that worsen asthma in a patient with an already diagnosed disease.
Atopy (hereditary predisposition to allergic diseases) is the main risk factor for asthma, and non-atopic individuals have a very low risk of developing asthma. Patients with asthma generally suffer from other atopic conditions such as allergic rhinitis and atopic dermatitis.
Familiarity of asthma indicates a genetic predisposition to the condition; several genes have been identified that may specifically contribute to the development of asthma.
Inhaled allergens, such as house dust mites during early childhood, are common triggers of asthma symptoms and are also involved in allergic sensitisation.
There are many other endogenous and environmental factors implicated in the aetiology of asthma such as obesity, occupational exposure to sensitisers, certain environmental pollutants, respiratory infections, and passive smoking.
Among asthma triggers, many stimuli such as inhaled allergens, viral infections, medications, and exercise induce airway calibre reduction and the onset of symptoms.
The characteristic symptoms of asthma are wheezing, dyspnoea and coughing, which regress either spontaneously or after treatment. Symptoms may worsen at night and lead to awakenings in the early morning hours.
In some patients there is increased mucus production with such density that it is difficult to expectorate.
The diagnosis of asthma is usually evident from symptoms and confirmed by performing spirometry, which demonstrates variable and reversible airway obstruction. Reversibility is demonstrated with the bronchodilator test.