Regional lung function in asbestos workers

Our plain-English summary of Regional lung function in asbestos workers, by D. Seaton (Thorax, 1977).

The study

• Author: D. Seaton
• Journal: Thorax
• Published: 1977;32(1):40-4
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Regional lung function was measured using radioactive xenon-133 in a group of normal subjects and in two groups of asbestos workers. When compared with the normal group, patients with pulmonary asbestosis showed impaired ventilation of the lower zones. Subjects with calcified pleural plaques without radiological evidence of lung parenchymal fibrosis did not show this abnormality.

In plain English

This study from Liverpool used scans with radioactive xenon-133 gas to measure how air and blood reached the upper, middle and lower zones of the lungs. The author compared nine healthy life-long non-smokers (mean age 60) with eleven workers who had an average of 30 years of industrial exposure to asbestos dust (mean age 61). Six workers had pulmonary asbestosis (group 1). Five had bilateral calcified pleural plaques with no X-ray sign of lung fibrosis (group 2). The article does not say which asbestos fiber types these workers were exposed to. In group 1, the spread of inhaled and injected xenon did not differ significantly from the healthy group. However, after 30 seconds of normal breathing, more xenon stayed in the lower zones. Group 2 did not show this lower-zone pattern. The author suggested that this lower-zone problem in asbestosis may be due mainly to lung tissue disease rather than pleural fibrosis, and that pleural calcification alone did not disturb regional ventilation as measured by this method. The author noted that the results show relative, not absolute, regional impairment.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Small clinical physiology study comparing regional lung function (xenon-133 lung scanning) in normal subjects and two groups of asbestos workers
• Who was studied: Nine normal, life-long non-smoking control subjects (mean age 60) and eleven asbestos-exposed patients (mean age 61). Group 1 was six subjects with radiographic and clinical features of asbestosis. Group 2 was five subjects with bilateral calcified pleural plaques without evidence of lung parenchymal fibrosis. Liverpool Cardiothoracic Surgical Centre. No study dates are given.
• Exposure: Industrial exposure to asbestos dust, averaging 30 years. The fiber types and jobs of the studied workers are not specified. Chrysotile is mentioned only when the author discusses earlier research on a possible mechanism.
• Main results:
  • In the nine normal subjects, a single inhaled breath of xenon reached the lower and middle zones equally, with an apparent decrease in the upper zone.
  • In group 1 (asbestosis), the zonal distribution of inhaled and injected xenon did not differ significantly from the control group.
  • In group 1 (asbestosis), retention of injected xenon after the washout procedure was markedly abnormal, with greater retention in the lower zone than the upper zone.
  • In group 2 (calcified pleural plaques), the steep lower-to-upper perfusion gradient seen in the control group and group 1 was not seen.
  • In group 2 (calcified pleural plaques), after washout there was slightly greater retention of xenon in the upper than the lower zone. Group 2 did not show the impaired basal washout seen in group 1.
• The authors' conclusion: The author suggested that the impaired lower-zone washout in asbestosis may be due primarily to lung parenchymal disease rather than coincidental pleural fibrosis. The author also suggested that pleural calcification alone, without radiological evidence of lung fibrosis, is insufficient to disturb regional ventilation as assessed by this technique.
• Limitations the authors state:
  • The results show relative impairment in certain lung regions and do not necessarily exclude disease in other parts.
  • Some subjects in both groups may have had radiologically undetectable apical emphysema from past smoking. This could account for the upper-zone trend in group 2 and could have been masked in group 1.
  • In normal subjects, the low amount of xenon retained after washout may increase the share of recorded counts that come from chest wall radiation. This affects the middle-zone readings.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Asbestosis, Pleural Plaques, Parenchymal Fibrosis.

Related studies

• Regional lung function in asbestos workers: observations and speculations — R.H. Secker-Walker, J.E. Ho (1982)
• Asbestos-related pleural plaques and lung function — L.C. Oliver, E.A. Eisen, et al. (1988)
• Diffuse pleural thickening in asbestos workers: disability and lung function abnormalities — C.R. McGavin, G. Sheers (1984)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• Pleural plaques and lung function in the Marysville worker cohort: a re-analysis — K. Zu, G. Tao, et al. (2016)
• Asbestos-induced pleural fibrosis and impaired lung function — D.A. Schwartz, L.J. Fuortes, et al. (1990)

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