ATS/ERS 2019 spirometry - how SpiroWright applies the standard
The 2019 ATS/ERS technical statement replaced the 2005 rules that most software in the field still runs. SpiroWright implements the 2019 criteria on every effort and every session, then shows its working on the report.
What changed in 2019 (and why it matters for your reports)
- Acceptability is now defined separately for FEV1 and FVC, plus a new "usable" category, so an effort with a poor end-of-test can still contribute a valid FEV1.
- End-of-forced-expiration (EOFE) is met by a plateau (≤0.025 L change for ≥1 s), or a forced expiratory time of 15 s, or when the patient cannot continue - the old "6-second rule" alone is no longer sufficient.
- Back-extrapolated volume (BEV) must be ≤5% of FVC or 0.100 L, whichever is greater - SpiroWright computes true back-extrapolation and reports BEV and FET on each effort.
- Repeatability: the two largest FVC values and the two largest FEV1 values must each agree within 0.150 L (0.100 L if FVC ≤1.0 L).
- Session grading A–F (and U) for FEV1 and FVC separately, based on the number of acceptable efforts and how closely they repeat - so a report can say "Grade A" instead of "3 acceptable" and mean something auditable.
- Z-scores over percent-predicted, with GLI reference equations, and lower limits of normal (LLN) rather than fixed cut-offs.
What SpiroWright does on every effort
Start of test
True back-extrapolation FEV1; BEV and FET shown per effort; hesitation and glottic closure flagged with coaching prompts.
End of test
Plateau / 15 s / cannot-continue EOFE logic; cough in the first second, early termination, leak and extra breaths flagged.
Session
Acceptable / usable / unacceptable per effort for FEV1 and FVC; repeatability check; A–F session grade; acceptability matrix printed on the report.
Reference values
GLI-2012 (LMS) and race-neutral GLI Global 2022, GLI 'Other' for African / South African populations, NHANES III and ECCS available; z-scores, LLN/ULN, percent-predicted with source cited.
Calibration verification & accuracy
ATS/ERS 2019 asks for a daily calibration check with a 3-litre syringe and BTPS correction. SpiroWright records the syringe and motor calibration with an ATS/ERS 2019 pass/fail verdict, takes BTPS from a live weather station or manual/altitude entry, and prints a calibration certificate. The AME / IQTeQ sensor is validated against ISO 26782 flow/volume reference waveforms via a Hans Rudolph simulator, with a measurement range of ±16 L/s.
Interpretation support
Obstructive / restrictive / mixed pattern with severity, GOLD 2026 staging and ABE group, pre/post-bronchodilator responsiveness, small-airways indices and lung-age estimate. The AI interpretation and referral letter are drafts for the clinician to review and sign - SpiroWright is decision support, not a diagnosis.
Reference: Graham BL et al. Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement. Am J Respir Crit Care Med 2019;200(8):e70–e88.
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