Sun10October0740PM 13

Which one of the following measurements is the most sensitive indicator of mild obstructive airway disease?

(Please select 1 option)

FEV1/FVC ratio

Forced expiratory volume in one second (FEV1) Incorrect answer selected

Forced expiratory flow (FEF25-75%) This is the correct answer

Forced vital capacity (FCV)

Peak expiratory flow (PEF)

Explanation

Forced expiratory volume in one second (FEV1) is the volume expired in the first second of maximal expiration after a maximal inspiration and indicates how quickly full lungs can be emptied. It is the most frequently measured parameter for assessment of bronchoconstriction.

The 'slow' vital capacity (VC) is the maximum volume of air exhaled after a maximal inspiration. Following a forced vital capacity (FVC) or slow vital capacity (VC) manoeuvre, the VC is normally equal to FVC unless airflow obstruction is present, in which case VC is usually higher than FVC.

The FEV1/FVC (Tiffeneau index) gives a clinically useful index of airflow limitation and is used to differentiate between a restrictive and obstructive respiratory disorder.

The forced expiratory volume (FEF25-75) is the average expired flow over the middle half (25-75%) of the FVC manoeuvre. This corresponds to the airflow from the resistance bronchioles. This is a more sensitive indicator of mild small airways narrowing than FEV1, but difficult to interpret if the VC (or FVC) is reduced or increased.

The peak expiratory flow (PEF) is maximal expiratory flow rate achieved, and is normally 8-14 L/second.

Answer Statistics

1

43%

2

24%

3

19%

4

1%

5

14%

Times answered: 279