For the diagnosis of obstructive airway disease which of the following is preferred: (A) Vital capacity, (B) Timed vital capacity, (C) Tidal volume, (D) Blood gas analysis
Answer is B. In obstructive airway diseases fev1 is markedly reduced than FVC. Maximum mid expiratory flow rate(fev 25 -75 %) is the more sensitive measure of small airway obstruction.