In the search for relief from asthma, great progress has been made since the days when every one suffering with dyspnea was classified as asthmatic. The separation of cases into those of cardiac and those of bronchial origin has been helpful. More useful still has been the subdivision of cases of bronchial asthma into those arising from extrinsic and from intrinsic causes.3 Extrinsic agents may be introduced by inhalation, by ingestion, through the unbroken skin, or by inoculation. Following their introduction, the phenomena of hypersensitiveness,4 sometimes called "atopy" or "allergy" and often confused with "anaphylaxis," may develop. Intrinsic causes may lie in the bronchial tree or in other parts of the body and may include foci of infection, nasal polypi, diseases of the subdiaphragmatic viscera, metabolic diseases, the so-called bacterial and winter asthmas, and secondary infection developing perhaps in the soil of an earlier pollen asthma.
PRESENT KNOWLEDGE OF BRONCHIAL ASTHMA. JAMA. 1927;89(12):968-969. doi:10.1001/jama.1927.02690120044017