title: Double tracer gas single-breath washout: reproducibility in healthy subjects and COPD.
abstract: The applicability and interpretation of inert tracer gas washout tests is hampered by the lack of feasible protocols and reproducibility data. We assessed feasibility, variability and reproducibility of a new easy to perform double tracer gas (DTG) single-breath washout (SBW) test and compared this with conventional nitrogen washouts. In 40 healthy nonsmokers and 20 patients with stable chronic obstructive pulmonary disease (COPD), we performed three N2 vital capacity SBWs, three N2 multiple-breath washouts and three tidal DTG-SBW tests. Follow-up was after 1 week, 1 month and 6 months. Main outcomes were the lung clearance index (LCI) (N2 multiple-breath washout), slope of phase III (dN2) (N2 vital capacity SBW) and slope of phase III (SIIIDTG) (DTG-SBW). In healthy subjects, mean±sd LCI at baseline was 6.94±0.61, dN2 0.99±0.42% N2 per litre and SIIIDTG -0.206±0.108 g·mol(-1)·L(-1). In COPD, LCI and dN2 were significantly higher (LCI 12.23±2.67, dN2 7.43±5.38% N2 per litre; p<0.001) and SIIIDTG significantly steeper (-0.653±0.428 g·mol(-1)·L(-1), p<0.001). Reproducibility was high for main outcome parameters: the intraclass correlation coefficient over 6 months was 0.77 (0.86 in COPD) for LCI, 0.82 (0.89) for dN2 and 0.83 (0.93) for SIIIDTG. The tidal DTG-SBW is a reproducible test in healthy and COPD subjects that seems attractive for use in routine clinical settings.
authors.affiliation: Klinik Schillerhöhe, Center for Respiratory Medicine and Thoracic Surgery, Robert-Bosch-Krankenhaus-GmbH, Stuttgart, Germany kim.husemann@klinik-schillerhoehe.de.
authors.forename: Kim
authors.initials: K
authors.lastname: Husemann
authors.affiliation: Klinik Schillerhöhe, Center for Respiratory Medicine and Thoracic Surgery, Robert-Bosch-Krankenhaus-GmbH, Stuttgart, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Berg
authors.affiliation: Klinik Schillerhöhe, Center for Respiratory Medicine and Thoracic Surgery, Robert-Bosch-Krankenhaus-GmbH, Stuttgart, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Engel
authors.affiliation: University of Stuttgart, Dept of Biomedical Engineering, Stuttgart, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Port
authors.affiliation: University of Stuttgart, Dept of Biomedical Engineering, Stuttgart, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Joppek
authors.affiliation: University of Stuttgart, Dept of Biomedical Engineering, Stuttgart, Germany.
authors.forename: Ziran
authors.initials: Z
authors.lastname: Tao
authors.affiliation: University Children's Hospital Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Singer
authors.affiliation: Helmholtz Zentrum Munich, Institute of Epidemiology I, Neuherberg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Schulz
authors.affiliation: Klinik Schillerhöhe, Center for Respiratory Medicine and Thoracic Surgery, Robert-Bosch-Krankenhaus-GmbH, Stuttgart, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kohlhäufl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001944:Breath Tests / Q000379:methods*; D002248:Carbon Monoxide / Q000737:chemistry; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000737:chemistry*; D010991:Plethysmography; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012907:Smoking; D013147:Spirometry; D013990:Tidal Volume; D016896:Treatment Outcome; D014797:Vital Capacity; D055815:Young Adult
chemical_list: D002248:Carbon Monoxide; D009584:Nitrogen