Correct height measurement for pulmonary function testing parameters.

antitussive or expectorant activity. Cough can also be reported in terms ofits intensity, loudness, duration, pressure, flow and volume relationships, cough “resistances” can be calculated to reflect the inertial, elastic and flow-resistive components of respiration, and changes in breathing mechanics in the upper and lower airways may be recorded.’ Under the same sponsorship as the Charlottesville group,2 we studied the behavior ofthe maximum expiratory flow-volume curve, closing volume information, the slope of the alveolar plateau (phase III)and the response tolow-density gas breathingfor 19 patients with chronic bronchitis given either guaifenesin (2,400 mg daily), or matched placebo, by double-blind random assignment for seven days following a one-week placebo washout. Clinical status was assessed by patient scoring ofcough attributes and chest discomfort, and by observer notation of physical signs. Reliance upon airbreathing, MEFV curves or closing volume data would have missed treatment differences. Significant decreases in delta N,% (p = 0.05) and the volume of isoflow (p 0.01) f r the guaifenesin group, compared with placebo, implied smallairways activity for the former consistent with the expected locus of activity of an expectorant. Guaifenesin was also statistically superior in improving cough characteristics and lessening chest discomfort, wheeze and breathlessness, indicating favorable objective and subjective clinical concomitants of the physiologic changes. Admittedly, we gave larger total doses than did Kuhn et al (28 doses over seven days compared with five doses over 30 hours) to patients with stable chronic cough. However, similar evidence of peripheral airways dysfunction occurs in nonsmokers with uncomplicated common colds34 and are susceptible to serial measurement. Changes in cough frequency would appear more valuable for studies of cough suppressants. Burton M. Cohen, M.D. , F.C.C.P Clinical Professor of Medicine, University ofMedicine and Dentistry of New Jersey-N ew Jersey Medical School, Elizabeth Reprint requests: Dr Cohen, 425 Westfield Avenue, Elizabeth, New Jersey 07208