The computer grades are QFVC=F and the QFEV1=A. The computer FVC grade is F because there are only two exhalations that lasted longer than 6-seconds and only one of the curves has a plateau (blue curve #3). The red curve #4 is unacceptable or rejected due to a large extrapolated volume. The lack of a plateau is due to the variations in volumes. However, the curves are very repeatable well within the 150 ml limit, as are the FVC values. Given the repeatability of the volume-time curves, there is reason to expect the FVC's to represent the subject maximal effort FVC's -- thus the revised grades of QFVC=B and QFEV1=A.
