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Randomized Controlled Trial
. 2010 Jan;104(1):76-82.
doi: 10.1016/j.rmed.2009.08.004. Epub 2009 Sep 6.

Distribution of emphysema in heavy smokers: impact on pulmonary function

Hester A Gietema  1 , Pieter Zanen, Arnold Schilham, Bram van Ginneken, Rob J van Klaveren, Mathias Prokop, Jan Willem J Lammers
Affiliations
Free article
Randomized Controlled Trial

Distribution of emphysema in heavy smokers: impact on pulmonary function

Hester A Gietema et al. Respir Med. 2010 Jan.
Free article

Abstract

Purpose: To investigate impact of distribution of computed tomography (CT) emphysema on severity of airflow limitation and gas exchange impairment in current and former heavy smokers participating in a lung cancer screening trial.

Materials and methods: In total 875 current and former heavy smokers underwent baseline low-dose CT (30 mAs) in our center and spirometry and diffusion capacity testing on the same day as part of the Dutch-Belgian Lung Cancer Screening Trial (NELSON). Emphysema was quantified for 872 subjects as the number of voxels with an apparent lowered X-ray attenuation coefficient. Voxels attenuated <-950 HU were categorized as representing severe emphysema (ES950), while voxels attenuated between -910 HU and -950 HU represented moderate emphysema (ES910). Impact of distribution on severity of pulmonary function impairment was investigated with logistic regression, adjusted for total amount of emphysema.

Results: For ES910 an apical distribution was associated with more airflow obstruction and gas exchange impairment than a basal distribution (both p<0.01). The FEV(1)/FVC ratio was 1.6% (95% CI 0.42% to 2.8%) lower for apical predominance than for basal predominance, for Tlco/V(A) the difference was 0.12% (95% CI 0.076-0.15%). Distribution of ES950 had no impact on FEV(1)/FVC ratio, while an apical distribution was associated with a 0.076% (95% CI 0.038-0.11%) lower Tlco/V(A) (p<0.001).

Conclusion: In a heavy smoking population, an apical distribution is associated with more severe gas exchange impairment than a basal distribution; for moderate emphysema it is also associated with a lower FEV(1)/FVC ratio. However, differences are small, and likely clinically irrelevant.

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Comment in

  • Are we measuring pulmonary emphysema?
    Hochhegger B, Marchiori E, Irion KL, Moreira J. Hochhegger B, et al. Respir Med. 2010 Jul;104(7):1073; author reply 1074. doi: 10.1016/j.rmed.2009.10.032. Epub 2010 Apr 13. Respir Med. 2010. PMID: 20392620 No abstract available.

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