Which of the following statements is false about the FEV1 measurement?

a. It is a volume measurement.
b. The recorded FEV1 must come from the same forced vital capacity (FVC) effort.
c. It is often compared to the size of the FVC.
d. It is a popular test.

ANS: B
The FEV1 is a measurement of the volume exhaled in the first second of the FVC (Figure 20-2, A). To ensure validity of the FEV1, the measurement must originate from a set of three acceptable FVC trials. The first second of forced exhalation begins at the zero time point (Figure 20-3). To ensure reliability of the FEV1, the largest FEV1 and second largest FEV1 from the acceptable tri-als should not vary by more than 0.150 L. Consistent with its definition, the largest FEV1 (body temperature, ambient pressure, saturated [BTPS]) measured is the patient's FEV1. The largest FEV1 sometimes comes from a different trial than the largest FVC.