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Original Research: COPD |

Characterizing Functional Lung Heterogeneity in COPD Using Reference Equations for CT Scan-Measured Lobar VolumesReference Equations for Lobar Volumes

Carolyn E. Come, MD, MPH; Alejandro A. Diaz, MD; Douglas Curran-Everett, PhD; Nivedita Muralidhar, BS; Craig P. Hersh, MD, MPH; Jordan A. Zach, BA; Joyce Schroeder, MD; David A. Lynch, MD; Bartolome Celli, MD, FCCP; George R. Washko, MD, MMSc; for the COPDGene Investigators
Author and Funding Information

From the Pulmonary and Critical Care Division (Drs Come, Diaz, Hersh, Celli, and Washko and Ms Muralidhar), and the Channing Laboratory (Dr Hersh), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA; the Division of Biostatistics and Bioinformatics (Dr Curran-Everett), National Jewish Health, Department of Biostatistics and Informatics, Colorado School of Public Health, Denver, CO; and the Division of Radiology (Mr Zach and Drs Schroeder and Lynch), National Jewish Health, University of Colorado School of Medicine, Denver, CO.

Correspondence to: Carolyn E. Come, MD, MPH, Pulmonary and Critical Care Division, Department of Medicine, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115; e-mail: ccome@partners.org


Funding/Support: The COPDGene study is funded by the National Institutes of Health (NIH) [Grants U01HL089897 and U01HL089856]. This work was supported by the NIH [Grant T32HL007633-26 to Dr Come and K23HL089353 to Dr Washko].

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(6):1607-1617. doi:10.1378/chest.12-1616
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Background:  CT scanning is increasingly used to characterize COPD. Although it is possible to obtain CT scan-measured lung lobe volumes, normal ranges remain unknown. Using COPDGene data, we developed reference equations for lobar volumes at maximal inflation (total lung capacity [TLC]) and relaxed exhalation (approximating functional residual capacity [FRC]).

Methods:  Linear regression was used to develop race-specific (non-Hispanic white [NHW], African American) reference equations for lobar volumes. Covariates included height and sex. Models were developed in a derivation cohort of 469 subjects with normal pulmonary function and validated in 546 similar subjects. These cohorts were combined to produce final prediction equations, which were applied to 2,191 subjects with old GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage II to IV COPD.

Results:  In the derivation cohort, women had smaller lobar volumes than men. Height positively correlated with lobar volumes. Adjusting for height, NHWs had larger total lung and lobar volumes at TLC than African Americans; at FRC, NHWs only had larger lower lobes. Age and weight had no effect on lobar volumes at TLC but had small effects at FRC. In subjects with COPD at TLC, upper lobes exceeded 100% of predicted values in GOLD II disease; lower lobes were only inflated to this degree in subjects with GOLD IV disease. At FRC, gas trapping was severe irrespective of disease severity and appeared uniform across the lobes.

Conclusions:  Reference equations for lobar volumes may be useful in assessing regional lung dysfunction and how it changes in response to pharmacologic therapies and surgical or endoscopic lung volume reduction.

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