title: Evaluation of nitrogen analyzers.
abstract: Commercial N2 analyzers are in current use in tests for pulmonary closing volume. To determine whether differences between instruments might lead to inconsistencies in the measurement of closing volume, we compared the performances of 3 different N2 analyzers. The tests involved measurement of accuracy under constant and varying conditions, response to transient changes in N2 concentration, long-term stability, and an assessment of mechanical integrity. There were moderate differences in accuracy among the 3 instruments that can be essentially eliminated at N2 concentrations less than 40 per cent by changing the calibration procedure for one of the instruments. There were also moderate differences in instrument stability, dependence on environmental conditions, and mechanical quality.
mesh_terms: D008176:Lung Volume Measurements / Q000295:instrumentation*; D009584:Nitrogen / Q000032:analysis*
chemical_list: D009584:Nitrogen