The expiratory rate during the third quarter of a maximal forced expiration (E50-75). A useful index of obstructive pulmonary disease.

0 BSTRUCTIVE pulmonary disease is one of the most important causes of dyspnea, and is a common reason for patients to seek medical attention. Since mild obstructive disease often goes unrecognized, there is need for a means of detect,ing its presence and grading its severity. When severe, it is often confused with congestive heart failure, and the common coexistence of the two imposes the urgent need for a ready means of assessing the pulmonary component of the patient’s disease. Although obstructive pulmonary disease produces a great many characteristic aberrations in function, from the clinical standpoint, the most practicable tests are those which measure the maximal expiratory rate. A kymographic tracing of a maximal forced expiration (expirogram)l serves this purpose well and we believe that, among the procedures suitable for day t,o day use in the practice of medicine, this is the best available measure of airway obstruction. Expirograms in severe emphysema or asthma present an abnormality so gross as to be recognizable at a glance. However, there are many instances which differ from the normal in minor respects and their evaluation requires carefully selected standards to distinguish normal variation from disease. Several parameters, all derivable from the expirogram, have been used as measures of the abnormality in obstructive disease. Some of these are shown in Fig. 1. The volume expired in the first second (F’SV)2 and the rate of expiration between the points where 200 CC. and 1,100 cc. have been cxpired” have three disadvantages. First, they deal with the early phase of the expiratory effort at which time the bronchial lumen is most patent and the effect of an obstructing lesion is minimal. Second, patients often fail to exhale as rapidly as possible during early expiration either because of pool motivation or technique. Finally, although of doubtful clinical importance, the inertia of most spirometers makes this portion of the curve differ somewhat from the true maximal expiratory flow rate. Examination of many expiratory tracings from patients with obstructive disease and apparent,ly