2.3 Correction of signal processing in MBW
In brief, the sensor-crosstalk error in the Exhalyzer D device underestimates O2 and CO2 gas concentrations and thus overestimates end-expiratory concentrations of N2. Elevated N2 concentrations cause a significant overestimation of the main MBW outcomes FRC and LCI as well as of the N2 back-diffusion from the lungs1. An updated Spiroware analysis software (v3.3.1, Eco Medics AG, Duernten, Switzerland), will correct automatically for this error. Previously reported results, however, need to be reanalyzed. In this study, we reanalyzed raw data (A-Files) using LungSim 1.01, a custom Python script developed by our group replicating the signal processing and outcome calculation used in Spiroware analysis software (v3.2.1 and 3.3.1) 1.
2.4 Re-assessment of clinimetric properties and statistical analysis
We present non-parametric summaries for skewed data and parametric summaries for normally distributed characteristics. Statistical analyses were performed using Stata 16.1 (StataCorp 2019, College Station; TX). Figures were created using Stata 16.1 or Graph Pad Prism 8 (Prism G 2018, La Jolla; California). The following clinimetric properties of LCI were examined and compared between the Spiroware software versions 3.2.1 and 3.3.1: