Abstract
There is growing interest in the nitrogen washout technique. The aim of our study was to compare a conventional FRC measurement (body box) with a commercially available nitrogen washout device. Because previous research for 2 commercially avialable devices didn't render satisfying results, our search for a nitrogen washout device continued.
Methods: 12 healthy subjects (9F/3M, 26-56years) performed FRC measurements with body box (Care Fusion®) which was compared to a nitrogen washout device (Eco Medics, exhalizer D®). All body box measurements were done threefold. All nitrogen washout measurements were done twice. If FRC did not reproduce within 10% an additional measurement was done. From all measurements we determined FRC and LCI (Lung Clearance Index).
Results: FRC values using N2-washout were significantly higher than using body box. After manual correction for N2-washout from the body compartment FRC was equal. LCI values were higher than predicted values by Exhalizer D software (Houltz et al. submitted). LCI values were higher than those obtained previously using NDD EasyOne Pro (P<0.001) and comparable to those obtained from Cosmed Quark PFT (P=0.20). Exhalizer D presents LCI at 2.5% N2 which is higher than 1/40 of 0.79 used by the other devices.
Conclusions: We recommend correction of FRC for N2 washout from the body. LCI values were highly different between the different systems. Since there is not really a golden standard, selection of proper reference values is important.
- Copyright ©ERS 2015