Asthma

Description

Asthma is a chronic, inflammatory disease of the airways that is characterized by bronchial hyperactivity and variable airway obstruction.

There are both allergic (atopic or extrinsic) and non-allergic (non-atopic or intrinsic) asthma forms. Allergic asthma is a disease of the atopic type. This is characterized by the immune system overreacting to certain external stimuli. In approximately 10% of patients a combined form of the disease is observed. While allergic asthma is more common in children, the non-allergic form occurs more frequently in adults.

Symptoms

Typical of asthma are symptoms of breathlessness (dyspnea). Exhalation is especially difficult, and this is often accompanied by wheezing (expiratory stridor). But symptoms such as a persistent dry cough can also sometimes indicate the disease. The impeded breathing and shortness of breath can lead to feelings of anxiety, with restlessness, speech difficulties and nausea. In acute attacks it can also lead to palpitations (tachycardia) and major respiratory distress, with a bluish discoloration of the lips and skin. Characteristic of asthma is the lack of symptoms in the intervals between attacks.

Causes and Risks

In asthma, two things come together. First, a predisposition that causes the inflamed bronchial tubes to be particularly sensitive to certain stimuli, and second, external triggers such as allergens, respiratory infections or cold air, which can cause the typical attacks of breathlessness. Allergic people who do or have suffered from hay fever, neurodermatitis or infantile eczema have a higher risk of asthma. Smoking is toxic to the respiratory system and increases vulnerability. Even passive smoking increases the risk of respiratory diseases. Moreover, smoking weakens the effect of asthma medications. Frequent respiratory infections make the airways vulnerable and can pave the way for asthma.

Non-allergic (intrinsic) asthma can have quite varying causes: infections, usually causes by viruses, make the airways susceptible and trigger inflammation that leads to cramping of the bronchi, mucous congestion, coughing and shortness of breath.

Certain medications such as analgesics (aspirin) or anti-inflammatory drugs (NSAIDs) may cause an asthmatic reaction. This is not an allergy but a genetically predisposed intolerance toward certain drugs, although to an observer it appears to be an allergic reaction.

Examination and Diagnosis

The diagnosis is often easy to make by means of the medical history and typical symptoms present. The lung function diagnostics for asthma typically comprise spirometry, pulse oximetry (non-invasive analysis of arterial oxygen saturation), and body plethysmography (a method for measuring lung and respiratory parameters). As previously mentioned, asthma is often allergic. Therefore it is very important to find out if there is a possible hypersensitivity to certain substances. This is done by skin tests and blood tests. In rare cases, challenge tests may be required, in which the patient inhales the allergen. An X-ray examination can help rule out any other diseases of the lungs. Also the coughed-up mucus, the so-called sputum, will be examined. If certain white blood cells, called eosinophilic granulocytes, are present this can be a sign of asthma. Bacteria may also be present in the sputum, if so indicating an infection of the respiratory tract rather than asthma. With allergic asthma, laboratory diagnostics such as differential blood count, immunoglobulins, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are of crucial importance.

Treatment

Although asthma cannot be cured, medications can be used to control the disease. This allows patients to largely maintain their quality of life: with optimal therapy they retain full physical performance. Drugs that are used include glucocorticoids (inhalation), beta sympathomimetics (inhalation), methylxanthines (theophylline), leukotriene antagonists, and mast cell stabilizers (cromoglicic acid, nedocromil, lodoxamide). In the milder stages of the disease the drugs are usually administered in the form of metered-dose inhalers. In later stages of the disease, oral or - especially in an asthma attack - intravenous application is often required.

Course and Prognosis

The symptoms of asthma can be kept under control via treatment and preventive measures. In half of all affected children, asthma subsides again after puberty. The probability that the illness "sorts itself out" rises when it is detected and treated early. In adulthood, asthma heals in about 20 percent of cases, and in 40 percent there is a significant improvement.

Miscellaneous/Other Comments

Acute severe asthma (status asthmaticus), a life-threatening asthma attack, is a dreaded complication which is not easily defeated with medication and so lasts for 24 hours or longer. It sometimes happens that the gas exchange in the lungs fails and the asthma patient is supplied with insufficient oxygen. In serious asthma attacks with severe shortness of breath, which does not improve when given emergency medications prescribed by a doctor, one should call an emergency doctor immediately. A severe attack can also result in hyperinflation of the lungs.