<prompt> Small airway resistance is best measured by:-FEV1Closing volumeTotal lung capacityFEV25-75  <response>: FEV timed: the percentage of total air that is exhaled in the given time. E.g: FEV1 : the air that is exhaled in the 1st second of forceful expiration. Reduced in airway obstruction FEV, 70. FEV1: 80 - 83 FEV2: 90 - 93 FEV3: 97 In exhaled air: First 13rd - is air from large airways Next 13rd - from small airways Last 13rd - from alveoli: Air from small airways is the mid - 13rd faction of expired air i.e the 25- 75th percent of air Exhaled FEV 0.25 - 0.75 FEV0.25 - 0.75 MMFR maximum mid expiratory flow rate reduction indicates small airway obstruction. 