Asthma Basics
Asthma is a chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed. Worldwide, around 300 million have been affected with this disease.
During attacks (exacerbations), the smooth muscle cells in the bronchi constrict and the airways become inflamed and swollen, with breathing becoming difficult.
Asthma is a chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed. Worldwide, around 300 million have been affected with this disease.
During attacks (exacerbations), the smooth muscle cells in the bronchi constrict and the airways become inflamed and swollen, with breathing becoming difficult.
Attacks can be prevented by avoiding triggering factors by drug treatment. Drugs are used for acute attacks, commonly inhaled β2-agonists. In more serious cases, drugs are used for long-term prevention, starting with inhaled corticosteroids, and then long-acting β2-agonists if necessary. Prognosis is good with treatment.
In contrast to chronic obstructive pulmonary disease and chronic bronchitis, the inflammation of asthma is reversible. In contrast to emphysema, asthma affects the bronchi and not the alveoli.
Public attention in the developed world has recently focused on asthma because of its rapidly increasing prevalence, affecting up to one in four urban children.
Causes
Asthma is caused by environmental and genetic factors, which can influence how severe asthma is and how well it responds to medication. Some environmental and genetic factors have been confirmed by further research, while others have not been.
Environmental Cause
1. Environmental tobacco smoke, especially maternal cigarette smoking, is associated with high risk of asthma prevalence and asthma morbidity, wheeze, and respiratory infections.
2. Poor air quality, from traffic pollution or high ozone levels, has been repeatedly associated with increased asthma morbidity and has a suggested association with asthma development that needs further research.
3. Caesarean sections have been associated with asthma when compared with vaginal birth; a meta-analysis found a 20 percent increase in asthma prevalence in children delivered by Caesarean section compared to those who were not.
4. Psychological stress has long been suspected of being an asthma trigger. Rather than stress directly causing the asthma symptoms, it is thought that stress modulates the immune system to increase the magnitude of the airway inflammatory response to allergens and irritants.
5. Viral respiratory infections at an early age, along with siblings and day care exposure, may be protective against asthma, although there have been controversial results, and this protection may depend on genetic context.
6. Antibiotic use early in life has been linked to development of asthma in several examples; it is thought that antibiotics make one susceptible to development of asthma because they modify gut flora, and thus the immune system.
Genetic Cause
Over 100 genes have been associated with asthma in at least one genetic association study. However, such studies must be repeated to ensure the findings are not due to chance. By the end of 2005, 25 genes had been associated with asthma in six or more separate populations.
Gene–environment interactions
Research suggests that some genetic variants may only cause asthma when they are combined with specific environmental exposures, and otherwise may not be risk factors for asthma.
The genetic trait, CD14 single nucleotide polymorphism (SNP) C-159T and exposure to endotoxin (a bacterial product) are a well-replicated example of a gene-environment interaction that is associated with asthma.
Endotoxin exposure varies from person to person and can come from several environmental sources, including environmental tobacco smoke, dogs, and farms. Researchers have found that risk for asthma changes based on a person’s genotype at CD14 C-159T and level of endotoxin exposure.
Signs and Symptoms of the Disease
Asthma exists in two states: the steady-state of chronic asthma and the acute state of an acute asthma exacerbation. The symptoms are different depending on what state the patient is in.
The Steady-State of Chronic Asthma: Common symptoms of asthma in a steady-state include: nighttime coughing, shortness of breath with exertion but no dyspnea at rest, a chronic ‘throat-clearing’ type cough, and complaints of a tight feeling in the chest.
Severity often correlates to an increase in symptoms. Symptoms can worsen gradually and rather insidiously, up to the point of an acute exacerbation of asthma. It is a common misconception that all people with asthma wheeze – some never wheeze and their disease may be confused with another Chronic obstructive pulmonary disease such as emphysema or chronic bronchitis.
The Acute State of an Acute Asthma Exacerbation: An acute exacerbation of asthma is commonly referred to as an asthma attack. The cardinal symptoms of an attack are shortness of breath (dyspnea), wheezing and chest tightness.
The shortness of breath is often regarded as the sine qua non of asthma, and in the late stages of an attack, air motion may be so impaired that no wheezing may be heard.
When present, the cough may sometimes produce clear sputum. The onset may be sudden, with a sense of constriction in the chest, breathing becomes difficult, and wheezing occurs (primarily upon expiration, but can be in both respiratory phases).
*Content from Wikipedia was used while writing this article.