Asthma is a chronic inflammatory disease of the airways. The disease manifests as recurrent attacks of wheezing, coughing and shortness of breath.
During an asthma attack, the muscles surrounding the airways contract, limiting the amount of air supply to the lungs. The lack of sufficient air supply results in a choking sensation. Asthma attacks induce the secretion of sputum and mucus, also which causes the airway to constrict even more, making the asthma attack worse.
Classic asthma symptoms include difficulty breathing, constant coughing and wheezing.
The Mechanism behind Asthma
Asthma is an overreaction to various stimuli. This overreaction can happen extremely quickly. The asthma attack causes three reactions: constriction of the airways, thickening of the inner lining and secretion of sputum into the airways. Together, these three reactions block the airways, making it difficult to breath and resulting in a shortness of breath. Children’s airways are smaller than adults, which makes their asthma attacks more severe.
Asthma is caused by a combination of complex environmental and genetic interactions. These factors influence both severity of the attack and response to treatment.
The Respiratory System
The respiratory system plays a major role in exchanging gases in the body – it brings oxygen to the lungs and disposes of carbon dioxide.
With every breath, air enters the body via the mouth or nose and moves down towards the lungs through the airway. The airway leads to the chest, where it splits into two – the bronchioli. Each of the bronchioli split into smaller tubes until they reach the nodes in the lungs. If the bronchioli are blocked, less oxygen reaches the lungs, resulting in respiratory problems.
The lining of the bronchiole has a number of glands which secrete mucus.
During an asthma attack the bronchiole contracts (bronchospasm) while the lining expands and fluids build up, further constricting the airway. In many cases, the asthma attack is occurs after exposure to stimuli. These stimuli are called allergens. Sometimes, the attack is the result of exercise or other agents that are not directly connected to an allergic reaction. Viral infections also cause asthma attacks.
When a person with asthma suffers from an asthma attack, the attack happens in two stages. During the first stage, the muscles surrounding the airways contract, and mast cells are released. Afterwards, the second stage of inflammation begins. A large number of inflamed cells build up in the airway and release substances which worsen the constriction of the surrounding muscle, cause a build-up of fluid in the lining of the bronchiole. The inflammation worsens over time and if left untreated, can become chronic and cause irreparable damage to the airways.
Asthma patients are usually treated for the acute symptoms which occur during an attack as well as medication to treat the inflammation.
Incidence (Prevalence) of Asthma
Asthma is considered to be the most common chronic diseases among children, affecting around 8%-10% of the population. The incidence of the disease is constantly growing, especially among Western countries and urban areas. The incidence of the disease varies among different populations. In Israel, asthma is more prevalent among city kids than children who live in suburbs or small towns. It is more prevalent among Jews, and affects Jews of Europeans descent more than Jews of African descent.
Half of the children diagnosed with asthma develop the disease by age 3 and most children with asthma have developed the disease by age 8.
There are a number of factors which affect the incidence of asthma among children. These include smoking (children who live in the house with a smoker), environmental factors, genetics, gender (more common among boys), allergies, repeated inflammation of the respiratory system. There is a growing trend of children diagnosed with asthma. This trend is due in part to an increasing awareness of the disease, and the growing use of air-conditioning, believed to be a factor in the development of the disease.
What Causes an Asthma Attack?
Most asthmatic children are sensitive to a number of attack-inducing agents however; the attack is dependent on a person's sensitivity level and the intensity of the exposure.
Smoking – do not smoke in an enclosed space (i.e. a house) with an asthmatic child.
Exposure to dust particles or allergens (dust mites, pollen, fur) – these materials can induce an asthma attack.
Physical Exertion – an attack induced by physical exertion can be prevented with the proper medication (prior to the work-out or with the first sign of an oncoming attack).
Different physical or mental states – stress, excitement, laughter
Inhaling dry, cold air or drinking an extremely cold beverage
Extreme weather changes
Viral infections of the upper respiratory system
Certain food colorings and additives
An asthma attack is a serious event that disrupts a person's normal routine. The attack manifests with wheezing, coughing, and shortness of breath. The symptoms subside after administering medication. The coughs at the beginning of the attack are dry and later on are accompanied by mucus. Not every patient suffers from all the symptoms.
Asthma is clinically classified into one of three categories:
Intermittent Asthma – this is the most common manifestation of asthma, affecting 75% of all children who suffer from asthma. Intermittent Asthma is characterized by relatively light asthma attacks, episodic attacks and relatively more time in between attacks (one in every six weeks). In between attacks, pulmonary function is normal.
Moderate Persistent Asthma – This manifestation affects around 20% of asthmatic children. The asthma attacks are more frequent for these children than they are for children who suffer from intermittent asthma. Additionally, the symptoms manifest in between attacks and pulmonary function is frequently abnormal.
Severe Persistent Asthma – This type of classification affects about 5% of all children suffering from asthma. This type of asthma is characterized by severe and frequent asthma attacks, and the child continues to suffer from certain asthmatic symptoms between attacks (shortness of breath, wheezing). Pulmonary function is abnormal all the time.