Lucas Boeck1, Anna Gensmer2, Sylvia Nyilas3, Bram Stieltjes4, Thomas J Re4, Michael Tamm1, Philipp Latzin3, Daiana Stolz5. 1. Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital Basel, Switzerland. 2. Division of Respiratory Medicine, University Children's Hospital Basel, Switzerland. 3. Division of Respiratory Medicine, University Children's Hospital Basel, Switzerland; Pediatric Respiratory Medicine, University Children's Hospital Bern, University of Bern, Switzerland. 4. Clinic of Radiology and Nuclear Medicine, University Hospital Basel, Switzerland. 5. Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital Basel, Switzerland. Electronic address: daiana.stolz@usb.ch.
Abstract
BACKGROUND: Current functional assessments do not allow a reliable assessment of small airways, which are a major site of disease in COPD. Single-breath washout (SBW) tests are feasible and reproducible methods for evaluating small airway disease. Their relevance in COPD remains unknown. METHODS: We performed a cross-sectional study in 65 patients with moderate to severe COPD. Phase III slope of nitrogen (SIIIN2) and double tracer gas (SIIIDTG) SBW tests were used as a measure of ventilation inhomogeneity. The association of both markers with established physiological and clinical features of COPD was assessed. RESULTS:Ventilation inhomogeneity as measured by SIIIN2 and SIIIDTG was increased in patients with COPD compared with healthy subjects (P < .001 and P < .001, respectively). SIIIN2 was associated with FEV1 predicted, residual volume (RV)/total lung capacity (TLC) and diffusing capacity of the lung for carbon monoxide (Dlco) (all P < .001). Furthermore, SIIIN2 was related to dyspnea, exercise-induced desaturation, and exercise capacity (P = .001, P < .001, and P = .047, respectively). SIIIDTG was associated with TLC, Dlco, and cough (P < .001, P = .001, and P = .009, respectively). In multivariate regression models, we demonstrated that these associations are largely independent of FEV1 and mostly stronger than associations with FEV1. In contrast, FEV1 was superior in predicting emphysema severity. CONCLUSIONS: SIIIN2 and SIIIDTG, two fast and clinically applicable measures of small airway disease, reflect different physiological and clinical aspects of COPD, largely independent of spirometry. TRIAL REGISTRY: ISRCTN99586989, Ethics committee Beider Basel (approval number 295/07).
RCT Entities:
BACKGROUND: Current functional assessments do not allow a reliable assessment of small airways, which are a major site of disease in COPD. Single-breath washout (SBW) tests are feasible and reproducible methods for evaluating small airway disease. Their relevance in COPD remains unknown. METHODS: We performed a cross-sectional study in 65 patients with moderate to severe COPD. Phase III slope of nitrogen (SIIIN2) and double tracer gas (SIIIDTG) SBW tests were used as a measure of ventilation inhomogeneity. The association of both markers with established physiological and clinical features of COPD was assessed. RESULTS: Ventilation inhomogeneity as measured by SIIIN2 and SIIIDTG was increased in patients with COPD compared with healthy subjects (P < .001 and P < .001, respectively). SIIIN2 was associated with FEV1 predicted, residual volume (RV)/total lung capacity (TLC) and diffusing capacity of the lung for carbon monoxide (Dlco) (all P < .001). Furthermore, SIIIN2 was related to dyspnea, exercise-induced desaturation, and exercise capacity (P = .001, P < .001, and P = .047, respectively). SIIIDTG was associated with TLC, Dlco, and cough (P < .001, P = .001, and P = .009, respectively). In multivariate regression models, we demonstrated that these associations are largely independent of FEV1 and mostly stronger than associations with FEV1. In contrast, FEV1 was superior in predicting emphysema severity. CONCLUSIONS: SIIIN2 and SIIIDTG, two fast and clinically applicable measures of small airway disease, reflect different physiological and clinical aspects of COPD, largely independent of spirometry. TRIAL REGISTRY: ISRCTN99586989, Ethics committee Beider Basel (approval number 295/07).
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