TABLE 1

In vitro functional residual capacity (FRC) measurements on each device

Lung model FRC volume	Trials	WIMR	EM	ndd v.2.00	ndd v.2.01
2.31	9	2.30±0.02	2.39±0.02	1.78±0.14	2.16±0.04
2.11	9	2.10±0.02	2.17±0.02	1.72±0.12	2.00±0.03
1.81	9	1.84±0.02	1.88±0.02	1.37±0.11	1.72±0.03
1.51	9	1.53±0.03	1.53±0.02	1.25±0.05	1.43±0.02

Data presented as mean±sd, unless otherwise stated. Measurements are in litres. WIMR: Woolcock in-house device; EM: Exhalyzer D device; ndd v.2.00: EasyOne Pro LAB device Version 2.00.01.05; ndd v.2.01: EasyOne Pro LAB device analysed in Version 2.01.00.09.