Chest
Volume 147, Issue 6, June 2015, Pages 1485-1493
Journal home page for Chest

Original Research: COPD
Diffusing Capacity for Carbon Monoxide Correlates Best With Tissue Volume From Quantitative CT Scanning Analysis

https://doi.org/10.1378/chest.14-1693Get rights and content

BACKGROUND

Quantitative analysis of high-resolution chest CT scan (QCT) is an established method for determining the severity and distribution of lung parenchymal destruction in patients with emphysema. Diffusing capacity of the lung for carbon monoxide (Dlco) is a traditional physiologic measure of emphysema severity and is probably influenced more by destruction of the alveolar capillary bed than by membrane diffusion per se. We reasoned that Dlco should correlate with tissue volume from QCT.

METHODS

A total of 460 patients with upper-lobe-predominant emphysema were enrolled in the study. The mean (SD) of percent predicted values for FEV1, total lung capacity, and Dlco were 30.6% (8.0%), 129.5% (18.1%), and 6.7% (13.1%), respectively. QCT was performed using custom software; the relationship between Dlco and various metrics from QCT were evaluated using Pearson correlation coefficients.

RESULTS

On average, whole-body plethysmography volumes were higher by 841 mL compared with QCT-calculated total lung volume. However, there was a strong correlation between these measurements (r = 0.824, P < .0001). Dlco correlated with total lung volume (r = 0.314, P < .0001), total tissue volume (r = 0.498, P < .0001), and percentage of lung with low density (−950 Hounsfield units) (r = −0.337, P < .0001).

CONCLUSIONS

In patients with severe emphysema, Dlco correlates best with total tissue volume, supporting the hypothesis that pulmonary capillary blood volume is the main determinant of Dlco in the human lung. The relationships between Dlco and various anatomic metrics of lung parenchymal destruction from QCT inform our understanding of the relationship between structure and function of the human lung.

Section snippets

Patient Selection

The patients reported in this analysis all presented with smoking-related, upper-lobe-predominant emphysema. They were evaluated and considered eligible for participation in one of five studies of bronchoscopic lung-volume reduction by implantation of intrabronchial valves (Spiration, Inc). The studies were carried out in North America, Europe, and South Africa (e-Tables 1, Table 2). Typical inclusion and exclusion criteria for these studies have been previously published23, 26, 27, 28, 29 and

Baseline Patient Characteristics

The characteristics of patients (N = 460) are shown in Table 2. Their mean ± SD age was 64.2 ± 6.8 years, and mean BMI was 25.8 ± 5.0. Just over one-half of the cohort (57.2%) were men, and 42.8% of the patients were women. Pulmonary function testing was performed at the beginning of the study. Spirometry showed an average FEV1/FVC of 32.8%. FEV1 was 30.6% ± 8.0% predicted and FVC was 71.8% ± 16.0% predicted. Patients had significant hyperinflation, with average TLC of 129.5% ± 18.1% predicted

Acknowledgments

Author contributions: C. B. C. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. I. B. served as principal author. S. S., X. G., H. O. C., and C. B. C. contributed to the study concept and design; data acquisition, analysis, and interpretation; and manuscript revision; I. B. contributed to data analysis and revision and writing the manuscript; and W. S. contributed to data analysis and manuscript

References (54)

  • N Macintyre et al.

    Standardisation of the single-breath determination of carbon monoxide uptake in the lung

    Eur Respir J

    (2005)
  • FJW Roughton et al.

    Relative importance of diffusion and chemical reaction rates in determining rate of exchange of gases in the human lung, with special reference to true diffusing capacity of pulmonary membrane and volume of blood in the lung capillaries

    J Appl Physiol

    (1957)
  • G Turato et al.

    Airway inflammation in severe chronic obstructive pulmonary disease: relationship with lung function and radiologic emphysema

    Am J Respir Crit Care Med

    (2002)
  • K Ando et al.

    Relationship between quantitative CT metrics and pulmonary function in combined pulmonary fibrosis and emphysema

    Lung

    (2013)
  • WM Thurlbeck et al.

    Emphysema: definition, imaging, and quantification

    AJR Am J Roentgenol

    (1994)
  • M Mishima et al.

    Complexity of terminal airspace geometry assessed by lung computed tomography in normal subjects and patients with chronic obstructive pulmonary disease

    Proc Natl Acad Sci U S A

    (1999)
  • Y Nakano et al.

    Comparison of low attenuation areas on computed tomographic scans between inner and outer segments of the lung in patients with chronic obstructive pulmonary disease: incidence and contribution to lung function

    Thorax

    (1999)
  • S Eda et al.

    The relations between expiratory chest CT using helical CT and pulmonary function tests in emphysema

    Am J Respir Crit Care Med

    (1997)
  • O Lucidarme et al.

    Expiratory CT scans for chronic airway disease: correlation with pulmonary function test results

    AJR Am J Roentgenol

    (1998)
  • S Matsuoka et al.

    Quantitative assessment of air trapping in chronic obstructive pulmonary disease using inspiratory and expiratory volumetric MDCT

    AJR Am J Roentgenol

    (2008)
  • S Matsuoka et al.

    Quantitative assessment of peripheral airway obstruction on paired expiratory/inspiratory thin-section computed tomography in chronic obstructive pulmonary disease with emphysema

    J Comput Assist Tomogr

    (2007)
  • RA O'Donnell et al.

    Relationship between peripheral airway dysfunction, airway obstruction, and neutrophilic inflammation in COPD

    Thorax

    (2004)
  • GA Gould et al.

    CT measurements of lung density in life can quantitate distal airspace enlargement—an essential defining feature of human emphysema

    Am Rev Respir Dis

    (1988)
  • DS Gierada et al.

    Repeatability of quantitative CT indexes of emphysema in patients evaluated for lung volume reduction surgery

    Radiology

    (2001)
  • GA Gould et al.

    Parenchymal emphysema measured by CT lung density correlates with lung function in patients with bullous disease

    Eur Respir J

    (1993)
  • OM Mets et al.

    Quantitative computed tomography in COPD: possibilities and limitations

    Lung

    (2012)
  • GA Gould et al.

    Lung CT density correlates with measurements of airflow limitation and the diffusing capacity

    Eur Respir J

    (1991)
  • Cited by (22)

    • Physical and mental health profile of patients with the early-onset severe COPD phenotype: A cross-sectional analysis

      2022, Clinical Nutrition
      Citation Excerpt :

      Scores ranged from 1.3, representing mild emphysema, to 23.7, representing severe emphysema, with the majority of subjects (75%) scoring >10.25. In line with this, early-onset severe COPD patients within the current study had a median (IQR) TLCO of 41.6 (36.1–55.2) %predicted, which is also indicative of emphysema [42,43]. The degree of emphysema was comparable with older severe subjects.

    • Normal Weight but Low Muscle Mass and Abdominally Obese: Implications for the Cardiometabolic Risk Profile in Chronic Obstructive Pulmonary Disease

      2017, Journal of the American Medical Directors Association
      Citation Excerpt :

      The majority of the patients had moderate-to-severe COPD (Global Initiative for Chronic Obstructive Lung Disease I/II/III/IV: 11.1%/49.4%/30.9%/8.6%). The average DLCO was 49.4 ± 14.6 %predicted, indicative of emphysema.30,31 Abdominal obesity was present in 61 of the 81 patients (75%) (Figure 1).

    View all citing articles on Scopus

    FUNDING/SUPPORT: This study was supported by Spiration Inc.

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

    View full text