Characterization of peripheral airway obstruction by pulmonary function parameters

Abstract

Introduction: Peripheral airway obstruction (PAO) is characterized by a concomitant decrease in FVC and FEV1 with normal FEV1/FVC and TLC and an increase in RV (classic criteria). However, several authors suggest the valuation of other parameters for its detection.

Objectives: To verify the presence of PAO through the criteria: 1) RV/TLC≥40%, 2) FEF’s<65% and 3) RV/TLC≥40%+FEF’s<65% in individuals with and without PAO by classic criteria; to identify the existence of agreement between the classic criteria and the proposed criteria: 1, 2, 3; to determine the sensitivity and specificity of the proposed criteria.

Methods: Cross-sectional study. 140 individuals were studied for the presence of PAO using the classic and the proposed criteria. Two groups were established: 70 subjects with classical criteria and 70 without.

Results: In the sample with PAO by the classic criteria, the RV/TLC criterion≥40% detected PAO in 97.1% of the subjects, the FEF’s<65% in 48.6% and the RV/TLC+FEF’s in 48.6% and in those without classic PAO criteria in 37.1%, 7.1% and 5.7%, respectively. There was a statistically significant agreement (p<0.001) between the classic and the proposed criteria, with the RV/TLC≥40% parameter being the most consistent (K=0.600;p<0.001). For RV/TLC criterion≥40%, a sensitivity of 97.1% and a specificity of 62.8% were obtained, for FEF’s<65%, 48.5% and 92.8% and for RV/TLC+FEF 48.5% and 94.2%, respectively.

Conclusion: The RV/TLC criterion≥40% revealed a high capacity for detecting PAO in individuals without the presence of the classic criteria and a high agreement with the latter, so its valorization represents an added value, reducing the occurrence of false negatives.