The place of forced expiratory volume in relation to other lung function tests.

The purpose of t h i study was to relate the forced expiratory volnme (FEV,) to other lung function tests and to assess the factor of "reversihility." Six h m-dred t h i i f i v e patients with "chronic nonspecific lung disease" were divided into those who showed an increase in the FEV, after a brnnchodilator aerosol (469) and those who showed no response (166). There was a linear relationship between the FEV, and the steady-state Musing capacity (gas trader) which was most obvious in the non-responsive group and did not apply to the single breath technique of meamring gas transfer. There was a tendency for the W,.,> to rise with a falling FEV, and, again, this was most marked in the nou-responsive group, the rising sharply for a FEV, below one titer. The findings w e s t , especially when the FEV, does not increase with the inhalation of a brnnchodilator, that information about the steady-state Dm mess-urement may be deducted and an irreversible FEV, below one titer nsnaUy indicates pulmonary insutEciency. Ih-monucrro~ C h r o n i c ainvay obstruction occurs in a wide range of lung diseases which are grouped together under the heading of "chronic obstructive lung dis-ease" or, in British terminology', "chronic non-specific lung disease." The measurement of the degree of obstruction is the most frequent investigation that is camed out in pulmonary laboratories and, without using elaborate techniques, it is the most important. A moderate amount of airway ob-struction2 will cause uneven ventilation in relation to blood flow and, in the later stages, will alter the blood gases and may lead eventually to right heart failure. The object of this paper is to relate the forced expiratory volume used as a measurement of obstruction , to other lung function tests and to assess the importance of the factor of "reversihility." Six hundred thirty-five patients who were referred for pulmonary assessment and who had a clinical diagnosis of chronic non-speci6c lung disease were used in the present investigation. METHODS The sohiects were all ambulatory or semiamhulatory patientc; no bedridden patients were included. Chronic non-specific lung disease war diawosed according to the defin~tion proposed at the Ciba Symposium' i.e, those suh-jects with one or more of the following. chronic mu& with emtoratnon, and paroxysmal or penistent excessive breathlessness, which are not solely attributable to: (a) lacal~zed lung disease of any kind, (h) …