A Simple Measure to Assess Hyperinflation and Air Trapping: 1-Forced Expiratory Volume in Three Second / Forced Vital Capacity

Abstract

Background: Several recent studies have suggested that1 minus-forced expiratory volume expired in 3 seconds /forced vital capacity (1-FEV3/FVC) may be an indicatorof distal airway obstruction and a promising measure toevaluate small airways dysfunction.Aims: To investigate the associations of 1-FEV3/FVC with the spirometric measures and lung volumesthat assess small airways dysfunction and reflectshyperinflation and air trapping.Study Design: Retrospective cross-sectional study.Methods: Retrospective assessment of a total of 1110cases who underwent body plethysmographic lungvolume estimations between a time span from 2005 to2012. Patients were assigned into two groups: firstly byFEV1/FVC (FEV1/FVC =70%);secondly by FEV3/FVC = LLN). Spirometricindices and lung volumes measured by whole-bodyplethysmography were compared in groups. Also thecorrelation of spirometric indices with measured lungvolumes were assessed in the whole-study populationand in subgroups stratified according to FEV1/FVC andFEV3/FVC.Results: Six hundred seven (54.7%) were male and 503(45.3%) were female, with a mean age of 52.5±15.6years. Mean FEV3/FVC and 1-FEV3/FVC were 87.05%,12.95%, respectively. The mean 1-FEV3/FVC was 4.9%in the FEV1/FVC >=70% group (n=644) vs. 24.1% in theFEV1/FVC