PT  - JOURNAL ARTICLE
AU  - Rachel Salvador-Ong
AU  - Erica Dijkers
AU  - Reindert Steenwijk van
AU  - Peter Sterk
TI  - Single-breath diffusion: Comparison between helium and methane as tracer gases in COPD and healthy controls
DP  - 2014 Sep 01
TA  - European Respiratory Journal
PG  - P1271
VI  - 44
IP  - Suppl 58
4099  - http://erj.ersjournals.com/content/44/Suppl_58/P1271.short
4100  - http://erj.ersjournals.com/content/44/Suppl_58/P1271.full
SO  - Eur Respir J2014 Sep 01; 44
AB  - Rationale: A real-time gas analyzer for methane (CH4 ) has been introduced as alternative for helium (He) in determining the alveolar volume (VA) for the single-breath diffusing capacity for carbon monoxide (DLCO). A difference can be expected due to the physical properties of these gases. Since the clinical relevance of changing tracer gases in single-breath diffusion has not been published, an adequate comparison is warranted.Objective: The aim of this study was to compare the DLCO and VA obtained using He and CH4 among COPD patients and healthy controls in order to examine whether their results are equivalent.Methods: This prospective, cross-over study included 10 healthy controls and 10 COPD patients. The DLCO and VA were measured in random order and in accordance to ATS/ERS guidelines. The correlations between the results were calculated using intraclass correlation test and visualized with Bland and Altman.Results: The intraclass correlation coefficient for the DLCO and VA was both 0.99 for the total group and in separating the groups the same intraclass correlation was found. The Bland and Altman analysis of DLCO and VA results from COPD patients showed a difference of -0.08 mmol/min/kPa (limits of agreement (LOA) -0.63 - 0.47) and -0.09 liter (LOA -0.33 - 0.15) respectively; for the healthy control the difference is 0.36 mmol/min/kPa (LOA -0.47 - 1.19) for DLCO and -0.03 liter (LOA -0.39 - 0.32) for VA.Conclusion: The DLCO and VA results obtained by CH4 as tracer gas correspond to those by He both among COPD patients and healthy controls. This suggests that CO diffusion capacity obtained by CH4 can be used for follow-up from previous tests obtained with He.