Which of the following is used to measure the resistance to small airways
Vital capacity
FEVt
Max. mid respiratory flow rates.
Closing volume
Ans. is 'c' i.e Max. Mid expiratory flow rates. * The following lines from Harrison support the answer.In obstructive lung disease, the hallmark is a decrease in expiratory flow rates. With fully established disease, the ratio of FEV1/FVC in decreased, as is the FEF25-75 %'( Max. mid expiratory flow rate).With early obstructive disease, which originates in the small airways, FEV1/FVC may be normal, the only abnormalities noted on routine testing of pulmonary function may be a depression in FEF25-75% and an abnormal configuration in the terminal portion of the forced expiratory flow-volume curve. "
Respiratory System