Pulmonary Physiology |

Lung Volume and Diffusion Changes Associated With an Isolated Reduction of the FEV3/FVC Ratio FREE TO VIEW

Zachary Morris*, MD; Angel Coz Yataco, MD; Dominik Starosta, MD
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Henry Ford Hospital, Detroit, MI

Chest. 2012;142(4_MeetingAbstracts):803A. doi:10.1378/chest.1384829
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SESSION TYPE: Physiology/PFTs/ Rehabilitation Posters

PRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PM

PURPOSE: An isolated reduction of the FEV3/FVC ratio is reported to identify mild or midflow airways obstruction and is associated with smoking. We sought to determine if this group of patients demonstrated significant differences in other lung function measurements compared to those with otherwise normal spirograms.

METHODS: Lung volumes and diffusing capacity were studied in subjects who had concomitant spirometry. Patients with restriction based on TLC were excluded, as well as repeat tests on the same patient. 15,785 pulmonary function tests were divided into 3 groups. (1) Normal FEV1/FVC and FEV3/FVC (n=9,377), (2) Only a reduced FEV3/FVC (n=984), (3) A reduced FEV1/FVC (n=5,424).

RESULTS: Subjects with only a reduced FEV3/FVC compared to those with normal FEV3/FVC and FEV1/FVC ratios had a higher mean percent predicted TLC (98.7% vs. 97.0%, p<0.001), RV (108.9 vs. 102.2, p<0.001), and RV/TLC ratio (110.0 vs. 105.3, p<0.001). They had a lower mean percent predicted FEV1 (82.4 vs. 90.2, p<0.001), IC (94.3 vs. 98.0, p<0.001) and DLCO (78.4 vs. 81.9, p<0.001). The reduced FEV3/FVC group also had lower mean BMI (31.1 vs. 31.7, p<0.011), were older (61.6 vs. 57.4, p<0.001), and more likely male (50.7 vs. 41.1, p<0.001), with no racial differences. Comparing the isolated reduced FEV3/FVC group to those with greater obstruction (reduced FEV1/FVC), similar but even greater differences were noted in all of the above measurements, though their mean age and sex was not significantly different.

CONCLUSIONS: Though lung volumes and diffusing capacity are within the normal range in those with an isolated reduction of the FEV3/FVC, there are significant changes compared to those with normal spirometry. This finding is a marker of milder airways obstruction and associated with additional subtle physiologic changes compared to those without obstruction on spirometry.

CLINICAL IMPLICATIONS: An isolated reduced FEV3/FVC ratio on spirometry is a significant finding and suggests an early injury pattern toward the development of hyperinflation, air trapping, and loss of diffusing capacity that occurs in more severely obstructed patients.

DISCLOSURE: The following authors have nothing to disclose: Zachary Morris, Angel Coz Yataco, Dominik Starosta

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Henry Ford Hospital, Detroit, MI




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