Management of difficult asthma

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It is convenient to divide asthma into two main groups: extrinsic and intrinsic asthma. This division is more a difference in triggering mechanisms than in pathophysiology, but it does enable us to formulate a management plan and, to a lesser degree, predict a response to that plan. In extrinsic asthma, the patient should have strongly positive immediate wheal and flare skin tests to antigens and, more importantly, a history to fit the positive skin test. Patients in whom such an association is not found are classified as having intrinsic asthma. Most patients with adult-onset asthma have intrinsic or a mixed type of asthma. Apart from differences in triggering mechanisms, there is also variation in location of airways obstruction (large versus small airways), in response to therapy, in drug requirements, and in degree of reversibility. All these factors make asthmatics an extremely heterogeneous group requiring individualized treatment.

Difficult asthma may be defined as asthma not effectively controlled by around-the-clock use of bronchodilators, by occasional bursts of corticosteroids, and by the addition of another nonsteroidal preparation. Most patients with difficult asthma will be in the group of intrinsic or mixed asthma. Extrinsic asthma is relatively less difficult to treat. After the diagnosis has been confirmed with appropriate history and skin tests, asthma is sometimes controlled by removing the offending antigen. However, in most instances, an around-the-clock oral bronchodilator must be added. Of the oral bronchodilators the theophylline compounds should be used as first-line drugs. The variation in theophylline dosage required is well . . .



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