The computer grades are QFVC=C, QFEV1=B. Curves 2 and 3 (red) are not acceptable because of large extrapolated volumes. The computer FVC grades is C as the difference between the largest (curve #1) and second largest (curve #4) FVC is 154 ml higher than the 150 ml needed for an A or B grade. However, you could argue that curve #4 is unacceptable do to variable effort and the FVC and FEV1 grades both should be D or F as there would be only one acceptable curve.. The computer FEV1 grade is B as if says are two, but not three, acceptable curves within 150 ml which is repeatable. This is an example of where the FEV1 grade may be considered by some reviewers as too high because of poor start of test or variable efforts. However, the FEV1's are very repeatable and it is unlikely that a better effort (higher peak flow) would produce a higher FEV1. In general, the FEV1 has a slight negative effort dependency where the largest FEV1 for some subjects is observed at approximately 85% to 90% of the maximum observed peak flow. The FVC values from all curves indicate that a complete inhalation is likely. Curve #1 appears to be a maximal effort with higher flows unlikely and has FVC and FEV1 values near the other curves. Thus the FEV1 grade is not changed but the FVC grade is raised slightly because its repeatability based on unacceptable curves (#2 and #3) -- QFVC=B and QFEV1=B.
