Summary of within- and between-manoeuvre acceptability criteria
| Within-manoeuvre criteria |
| Individual spirograms are “acceptable” if |
| They are free from artefacts 3 |
| Cough during the first second of exhalation |
| Glottis closure that influences the measurement |
| Early termination or cut-off |
| Effort that is not maximal throughout |
| Leak |
| Obstructed mouthpiece |
| They have good starts |
| Extrapolated volume <5% of FVC or 0.15 L, whichever is greater |
| They show satisfactory exhalation |
| Duration of ≥6 s (3 s for children) or a plateau in the volume–time curve or |
| If the subject cannot or should not continue to exhale |
| Between-manoeuvre criteria |
| After three acceptable spirograms have been obtained, apply the following tests |
| The two largest values of FVC must be within 0.150 L of each other |
| The two largest values of FEV1 must be within 0.150 L of each other |
| If both of these criteria are met, the test session may be concluded |
| If both of these criteria are not met, continue testing until |
| Both of the criteria are met with analysis of additional acceptable spirograms or |
| A total of eight tests have been performed (optional) or |
| The patient/subject cannot or should not continue |
| Save, as a minimum, the three satisfactory manoeuvres |
FVC: forced vital capacity; FEV1: forced expiratory volume in one second.