Expiratory and inspiratory vital capacities and the ventilatory pattern severity

Introduction: Slow vital capacity (SVC) can be determined by expiratory vital capacity (EVC) or inspiratory vital capacity (IVC). It would be expect that VC obtained through EVC or IVC would be similar, but this is not observed in all individuals. Aims: To determine EVC and IVC in patients with airway obstruction and pulmonary restriction according to ventilatory pattern severity; to characterize the associations between EVC, IVC and EVC and IVC difference (EVC-IVC) and FEV1 and TLC. Methods: Cross-sectional study. Sample included 224 individuals. In half of the sample, VC was determined first by EVC and then by IVC and in the other half in the reverse order. Subjects were divided into airway obstruction and pulmonary restriction groups and those were subdivided according to ventilatory defect severity. Results: In airway obstruction group the EVC and IVC differed significantly between mild and severe and mild and very severe groups (p Conclusions: The maneuver performed to determine SVC should take into consideration existing ventilatory pattern. IVC should be chosen in the presence of severe and very severe airway obstruction and in mild and moderate airway obstruction EVC it’s preferable, because they promotes in these particular circumstances a greater air mobilization capacity.