[Bronchial asthma. Pathogenesis and clinical aspects]

Asthma bronchiale (a.b.) is defined as paroxysmal or permanent, partly or completely reversible dyspnoea due to a bronchospasm resulting from pathological hyperreactivity of the bronchial system. In the pathogenesis participate allergic, immuno-infiltrative and genetic factors, irritating substances (environment) and infectious. The allergic constituent acts via sensitization and allergization of the mast cell, to its degranulation with release of mediators (histamine, serotonin, leukotrienes, thromboxane, PAF) with subsequent bronchoconstriction and production of viscous mucus. As to adrenergic factors, a block of beta-adrenergic receptors and reduced adrenal function is involved. As to non-adrenergic factors an increased sensitivity of the parasympathetic--vagus is involved which conditions bronchoconstriction and hyperkrinia. From the clinical aspect extrinsic (atopic) and intrinsic (cryptogenic) asthma bronchiale can be differentiated. The former is encountered more frequently in childhood and adolescence, in subjects with a positive family-history, high IgE and positive skin tests and a known allergen. The latter type of a.b. is found in adolescence, in subjects with a negative family-history, with eosinophilia; it is conditioned by infection (e.g. chronic bronchitis), strain, cold and takes a dangerous course (aspirin). As to the course, attacks of a.b. are involved with a symptom-free interval (extrinsic a.) easily controlled by treatment. Then there is the chronic form with a variable course and the necessity of permanent treatment. Status asthmaticus is in recent years with increasing frequency the cause of death and thus calls for maximal treatment. It is the third most serious form of a.b. Assessment of arterial blood gases is very important as a check of treatment as well as from the prognostic aspect (cross-over intubation). From the differential diagnostic aspect we must consider the asthmoid component in chronic bronchitis, pulmonary embolism, left-sided cardiac failure, tracheal or bronchial compression by an aortal aneurysm, tumour. The differential diagnosis is not always easy.