According to the World Health Organisation data, 5% of world population suffers from asthma which appears in all ages, but mainly before the age of 10.
Asthma comes in attacks which can last from a few minutes to several hours. During an attack the patient experiences shortness of breath (dyspnoea), cough and wheezing.
Severe symptoms of suffocation can develop if asthma is complicated by a coexistent upper airway infection. These can be triggered by inhaling specific allergens or if the inhaled air is very cold or very hot. Between attacks, patients generally remain symptom-free.
An asthma attack can also be triggered by physical activity. In women the disease often worsens before menstruation. Drugs, especially aspirin, can also exacerbate asthma. Other asthma triggers include polluted environmental air, workplace health issues, infections and emotional stress.
Forms of asthma
Asthma can be subdivided into the allergic and non-allergic (intrinsic) asthma.
The latter is characterised by having no known cause. Possible causes could include viruses or antibodies that target the lung tissue. Allergic asthma can typically be caused or exacerbated by specific allergens (i.e. substances that trigger an immune response and usually do not harm a healthy body). A history of atopy is the strongest risk factor for the development of allergic asthma.
Atopy or atopic syndrome is an allergic hypersensitivity affecting parts of the body not in direct contact with the allergen. Affected individuals have a hereditary predisposition to various allergic diseases including asthma. In childhood, the prognosis of asthma is excellent; 50% of children who suffer from asthma in childhood are disease-free in adulthood. However, asthma can be very dangerous, for a patient can suffocate to death during a severe attack.
The development of allergic asthma is IgE antibody-mediated. When the patient inhales an allergen, special immune cells called mastocytes begin to secrete many inflammatory mediators, most importantly histamine, under the influence of IgE antibodies. The secretion of inflammatory mediators leads to an inflammatory reaction. Airway mucosa swells up and narrows the airways. If the patient is not treated aggressively, permanent injury of airway mucosa may result.
On appearance of asthma symptoms, diagnosis is made on the basis of a good patient history and a physical exam. The final diagnosis is made based on the results of the pulmonary function tests (PFTs). Asthma can also be confirmed by exposing the airways to special substances and measuring their response.
Asthma prevention is directed mainly at preventing acute attacks that present with cough, dyspnoea, wheezing, a choking sensation and chest tightness.
Asthma patients need to;
Know the triggers of their asthma attacks, which may be various allergens (pollen, dust mites, cat fur, etc.), viral infections of the upper airways, physical stress, cigarette smoke, emotional stress, cold and/or polluted air as well as certain medications;
Effectively use their prescribed inhaler to have maximum impact.
Have a plan of action detailing how to act in the case of an acute attack, even before medical assistance is sought.
Asthma therapy generally includes avoidance of all known triggers as well as the use of one or more medications. Because the disease varies with time, it is important to closely follow the symptoms and control the pulmonary function. Because of the need for adequate treatment adjustment, a good cooperation between the patient and the physician is required.
The aim of the therapy in the first line is the treatment of chronic inflammation of the airways and prevention and control of the acute exacerbations.
Two groups of medications are used to that effect:
Short-acting drugs, such as the bronchodilators, are used for immediate treatment of attacks. These medications are symptomatic medications; they are used on a per need basis, i.e. when the patient first starts to feel dyspnoea. These medications act to dilate the airways by relaxing the airway muscles. The group includes the short-acting beta-2-agonists such as salbutamol. They take their effect in a few minutes and last for 4-6 hours.
Medications for long-term control used on a daily basis include the anti-inflammatory drugs such as the inhalation corticosteroids that represent the initial drug of choice. They may also be used in combination with the long-acting beta-2-agonists and antileukotrienes, etc. in the case that the desired control has not been achieved.
In patients with allergic asthma for whom the culprit for the attacks is the known hypersensitivity to a specific allergen, the following may be of use:
Avoidance of the known allergens is the most important step that a patient can take towards prevention of allergic reactions and decrease of the number of asthma attacks. In immunotherapy, increased amounts of the responsible allergen are injected subcutaneously with the aim of conditioning the immune system and reducing its sensitivity to this allergen. The goal is to ameliorate the asthma symptoms, as well as to reduce the need for medications and the danger of future serious asthma attacks.
Initially, injections are administered once or many times per week for about 30 weeks. With time, the doses are administered in increasingly long intervals or once per month. The therapy is carried out for 3 to 5 years, in some cases even longer.
Medications such as systemic anti-histamines; they can be used regularly in the case of dust mite and cat fur hypersensitivity, or only during the periods of greatest exposure, such as in the spring, in the case of pollen hypersensitivity.
In addition, important measures include professional counselling (because choosing the wrong profession may expose the patient to the known allergic triggers) as well as vaccination against influenza and pneumococcus.