Which one of the following is the best measure of airflow obstruction?
A. Diffusing capacity DLCO.
B. Residual volume RV. C. 1-Second forced expiratory volume FEV1.
D. 1- FEV1/FVC ratio
Ans.
D. 1- FEV1/FVC ratio
A decrease in the 1-second forced
expiratory volume—forced vital capacity FEV1/ FVC. ratio is the hallmark of airflow obstruction
The FEV1 is the volume of air forcefully expired during the first second after
a maximal inhalation; the FVC is the total volume of air that can be forcibly
expelled from the lungs after a maximal inhalation. The FEy1 is decrease
obstructive as well as restrictive lung disease capacity DLCO. and the residual volume RV. do not identify airway obstruction. The DLCO
indicates the adequacy of the alveolar—capillary membrane; the RV is the volume
of air remaining in the lungs after a maximal expiratory effort.
