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Published on: February 9, 2022
Instrumentation for the analysis of airflow limitation by the negative expiratory pressure technique
Illene Teixeira1, Luiz G Q Nunes, Pedro L Melo
1Biomedical Instrumentation Laboratory, Institute of Biology, Faculty of Engineering, State University of Rio de Janeiro, Brazil. illene@ig.com.br
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.
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