Spirometry score system
| Score | FVL visual analysis | FEV1 and FVC repeatability | |
| FEV1 mL | FVC mL | ||
| 2 | Sharp PEF, and steep upslope, and absent BEV (or <100 mL or 5% FVC if available in the printout) | <100 | <100 |
| 1 | >100<200 | >100<200 | |
| 0 | Either flat PEF, or flat upslope, or evident BEV (or >100 ml or 5% FVC if available in the printout) | >200 | >200 |
FEV1: forced expiratory volume in one second; FVC: forced vital capacity; FVL: flow-volume loop; BEV: back extrapolation volume; PEF: peak expiratory flow; upslope: upslope of the FVL.