I had experienced in the last two years several gross discrepancies (and may other not so obvious) with potential overestimation of FEV1 in young children.
In spite of strict adherence to ERS/ATS quality criteria of spirometry, our pediatric patients, in an acute setting [asthma during mild exacerbation with wheezing and mild/moderate distress] generated perfectly reproducible curves with FEV1 above 100% predicted.
I performed a new calibration, did a strict evaluation of ambient settings [temperature, pressure, humidity] and did a new height measurement of child [we use a protocol, involving a Harpenden stadiometer, in our clinic]... And same values came into attention.
I was intrigued by such scenarios in patients in whom one can expect a FEV1 between 60-80% predicted.
Did you experience a similar scenario?