title: Airflow pattern complexity during resting breathing in patients with COPD: effect of airway obstruction.
abstract: We investigated the influence of airway obstruction in the complexity of the airflow pattern in COPD and its use as a marker of disease activity. The sample entropy (SampEnV') and the variability (SDV') of the airflow pattern were measured in a group of 88 subjects with various levels of airway obstruction. Airway obstruction resulted in a reduction in the SampEnV' (p<0.0001) that was significantly correlated with spirometric indices of airway obstruction (R=0.50, p<0.001). The early adverse effects in mild airway obstruction were detected by the SampEnV' with an accuracy of 84%. SDV' increased with airway obstruction (p<0.002). We conclude that (1) the airflow patterns in COPD exhibit reduced complexity compared with healthy subjects; (2) this reduction in complexity is proportional to airway obstruction; and (3) the evaluation of SampEnV' may provide novel respiratory biomarkers suitable to facilitate the diagnosis of respiratory abnormalities in COPD.
authors: Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Brazil.
authors: Karla Kristine
authors: KK
authors: Dames
authors: Pulmonary Function Laboratory, Faculty of Medical Sciences, State University of Rio de Janeiro, Brazil.
authors: Agnaldo José
authors: AJ
authors: Lopes
authors: Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Brazil; Clinical and Experimental Research Laboratory in Vascular Biology, Institute of Biology, State University of Rio de Janeiro, Brazil. Electronic address: plopes@uerj.br.
authors: Pedro Lopes
authors: PL
authors: de Melo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000392:Air Movements; D000403:Airway Resistance / Q000502:physiology; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods; D012146:Rest / Q000502:physiology*; D013147:Spirometry; D018709:Statistics, Nonparametric; D013990:Tidal Volume / Q000502:physiology; D014797:Vital Capacity / Q000502:physiology
keywords: COPD; Complexity; Diagnostic; Homeokinesis; Sample entropy; Variability