Related Experiment Video
Updated: Oct 7, 2025
Three-Dimensional Phase Resolved Functional Lung Magnetic Resonance Imaging
Published on: June 21, 2024
Differences between FEV6, FVC and VC at the diagnosis of obstructive ventilatory defect
C S Sousa1, D B Coelho2, P Amorim2
1Hospital Central do Funchal, Portugal.
Introduction:
The diagnosis of airway obstruction can be made through FEV1/FVC ratio <0.7 or FEV1/VC ratio < lower limit of normality (LLN). Several authors advocate that FEV1/FEV6 ratio is an alternative to diagnosing obstructive ventilatory defect, while others have determined that the best cut-off for this ratio (best combined sensitivity and specificity) is 0.73.
Objective:
To evaluate the non-inferiority of FEV1/FEV6 ratio < 0.73 when compared to FEV1/FVC ratio < 0.7 and FEV1/VC < LLN in diagnosing airway obstruction.
Methods:
A retrospective analysis of the medical records from patients who underwent spirometry or plethysmography in a university central hospital from June 1st to December 31st, 2018 was carried out. Only medical records which included FEV1/FVC < 0.7 or FEV1/VC < LLN were selected, and these results were compared to FEV1/FEV6 ratio.
Results:
A total of 526 patients with obstructive ventilatory defect were identified by one of the two ratios described. Of these, 95.1%, 87.4% and 88.6% were obstructive by FEV1/FVC, FEV1/VC, and FEV1/FEV6 ratio, respectively. The positive predictive value (PPV) of FEV1/FEV6 in relation to FEV1/FVC ratio was 99.6% (p < 0.001) with a diagnostic efficacy of 92.8%, whereas the PPV of FEV1/FEV6 in relation to FEV1/VC was 91.0% (p < 0.001) and diagnostic efficacy was 85.2%. Most false negatives, comparing FEV6 with the other two tests, were found in patients with FEV1 > 70% (mild obstruction) and in individuals aged >50 years.
Conclusions:
FEV1/FEV6 < 0.73 may be a good alternative ratio, as it is non-inferior to FEV1/VC and FEV1/FVC in diagnosing obstructive ventilatory defect.
More Related Videos
05:56Author Spotlight: Enhancing Diagnostic Strategies and Biomarker Development for Comprehensive Lung Function Analysis
Published on: August 9, 2024
07:09Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
Related Concept Videos
01:15Respiratory Volumes
Tidal Volume (TV) Tidal volume (TV) is the air inhaled or exhaled in a...
01:27Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History
01:19Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
01:29Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
01:26Respiratory Volumes and Capacities I
01:22Respiratory Volumes and Capacities