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The bronchospastic component in 100 patients with moderate to severe chronic bronchitis and emphysema was investigated by determination of serial, timed vital capacity (FEV1) before and after isoproterenol hydrochloride inhalation. Four hundred twenty-five studies over a one- to five-year period showed that the FEV1decreases with progression of disease; however, the degree of bronchospasm did not change significantly, indicating a tendency for bronchospasm to persist in many patients in spite of the use of bronchodilators (95 patients), daily intermittent positive pressure breathing (51 patients), and steroids (21 patients). A paradoxical response to isoproterenol was encountered in nine patients. Eighty-four patients showed definite improvement in FEV1in one or more tests after isoproterenol administration. It is concluded that a bronchospastic component exists in most patients with chronic bronchitis and emphysema, whether or not a history of asthma is elicited.
John K. Curtis (Mon,) studied this question.