title: Instrumentation for the analysis of airflow limitation by the negative expiratory pressure technique.
abstract: The aim of this work is to describe a new instrument based on the negative expiratory pressure technique able to detect expiratory flow limitation (EFL) in patients with respiratory diseases. First, we describe the design details of a virtual instrument able to apply a low pressure at the mouth during tidal expiration, simultaneously measure flow and pressure, and automatically elaborate flow-volume curves. Then, the system accuracy is evaluated investigating normal subjects and patients with chronic obstructive pulmonary disease (COPD). These experimental results revealed higher (p〈0.001) EFL in COPD patients (58.5±19.9%) than in normal volunteers (1.5±2.5%). These results are in close agreement with the physiology, confirming the high scientific and clinical potential of this system.
authors.affiliation: Biomedical Instrumentation Laboratory, Institute of Biology, Faculty of Engineering, State University of Rio de Janeiro, Brazil. illene@ig.com.br
authors.forename: Illene
authors.initials: I
authors.lastname: Teixeira
authors.forename: Luiz G Q
authors.initials: LG
authors.lastname: Nunes
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Melo
mesh_terms: D000328:Adult; D000368:Aged; D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008176:Lung Volume Measurements / Q000295:instrumentation*; D008297:Male; D008365:Manometry / Q000295:instrumentation*; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013147:Spirometry / Q000295:instrumentation*; D015919:Ventilators, Negative-Pressure