Lung cinescintigraphy in the dynamic assessment of ventilation and mucociliary clearance of asbestos cement workers

Our plain-English summary of Lung cinescintigraphy in the dynamic assessment of ventilation and mucociliary clearance of asbestos cement workers, by L. Di Lorenzo, M. Mele, M.M. Pegorari, et al (Occupational and Environmental Medicine, 1996).

The study

• Authors: L. Di Lorenzo, M. Mele, M.M. Pegorari, A. Fratello, C. Zocchetti, D. Capozzi
• Journal: Occupational and Environmental Medicine
• Published: 1996;53(9):628-35
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: To verify in vivo whether lung cinescintigraphy confirms the effect of asbestos on the patency of the smallest airways and on the efficiency of mucociliary clearance in asbestos cement workers.

Methods: 39 male subjects were examined: 30 asbestos cement workers and nine workers never exposed to occupational respiratory irritants. All subjects had a chest radiograph (International Labour Organisation (ILO) 1980); standard questionnaire on chronic bronchitis; spirometry; arterial blood gas analysis; carbon monoxide transfer factor (TLcosb); pulmonary O2 and CO2 ductances (DuO2, DuCO2); electrocardiogram; and lung cinescintigraphy after radioaerosol inhalation for the measurement of mucociliary clearance time in vivo in the smallest ciliated airways and for the assessment of radioaerosol deposition in alveoli (alveolar deposition index).

Results: Apart from nine non-exposed subjects, the 30 asbestos cement workers were so classified on the basis of chest radiography: nine of them as healthy exposed, 10 with pleural plaques, and 11 with asbestosis. The four groups had similar ages, work seniority, and smoking habits. Exercise dyspnoea was significantly more frequent in asbestos cement workers. Lung function variables of workers with effects related to asbestos were significantly lower than the other two groups. The PaO2, TLcOsb and DuO2 mean values were significantly lower in exposed workers than non-exposed. The mean PacO2 value was significantly higher in the asbestosis group than in the other three groups. Workers with effects related to asbestos showed a significantly lower alveolar deposition index and a significantly higher mucociliary clearance time than the other two groups. Subjects with asbestosis showed similar differences from those with pleural plaques.

Conclusions: Lung cinescintigraphy confirms in vivo the effects of asbestos on bronchiolar and alveolar patency and on efficiency of mucociliary clearance in the smallest ciliated airways. Finally, lung cinescintigraphic variables are able to discriminate workers with asbestosis from those with pleural plaques.

In plain English

This Italian study compared 30 former asbestos cement workers, recruited through a union, with nine union members never exposed to respiratory irritant dust or fumes. The cement was 20% asbestos: 70%-80% chrysotile, 15%-20% crocidolite, the rest amosite. By chest x ray, the exposed men were classed as healthy exposed (9), pleural plaques (10) or asbestosis (11). All had lung function tests and lung cinescintigraphy, a scan after inhaling a radioactive aerosol. It estimated how much reached the deepest lung (alveolar deposition index) and how fast small airways cleared the particles. Mean alveolar deposition index was 84.3% (unexposed), 72.8% (healthy exposed), 56.2% (plaques) and 36.1% (asbestosis). Both plaque and asbestosis groups were significantly lower than the other two, and asbestosis lower than plaques. Mean clearance time was significantly longer only with asbestosis (312.5 minutes, against 62.6 to 131.2 in other groups). Blood oxygen was significantly lower in all three exposed groups. Including smoking in the analysis showed no difference attributable to it; nobody had smoked over 10 pack-years. The authors concluded that the method appears feasible for studying these workers.

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: Cross-sectional comparison of four groups (unexposed controls and three groups of exposed workers classified by chest x ray), using lung function tests and radioaerosol lung cinescintigraphy
• Who was studied: 39 men: 30 former workers of an asbestos cement factory, recruited through a union (30 of 35 members asked agreed), and 9 male volunteers from the same union never exposed to respiratory irritant dust or fumes. The exposed men were classified as 9 healthy exposed, 10 with pleural plaques and 11 with asbestosis. Study centres were in Bari and Milan, Italy.
• Exposure: Work in asbestos cement made of 80% cement and 20% asbestos; the asbestos mixtures were 70%-80% chrysotile, 15%-20% crocidolite, and the rest amosite. Mean work seniority ranged from 18.9 to 23.5 years across the exposed groups. No fiber measurements were given.
• Main results:
  • Mean alveolar deposition index was 84.3% (non-exposed), 72.8% (healthy exposed), 56.2% (pleural plaques) and 36.1% (asbestosis). The pleural plaque and asbestosis groups were significantly lower than both the non-exposed and healthy exposed groups.
  • The alveolar deposition index was also significantly lower in the asbestosis group than in the pleural plaque group.
  • Mean mucociliary clearance time was 62.6 min (non-exposed), 112.7 min (healthy exposed), 131.2 min (pleural plaques) and 312.5 min (asbestosis). It was significantly higher in the asbestosis group than in the other three groups. The longer times in the other two exposed groups compared with controls were not statistically significant.
  • Mean arterial oxygen tension was significantly lower in all three exposed groups (83.4, 83.1 and 79.3 mm Hg) than in controls (94.9 mm Hg).
  • Mean arterial carbon dioxide tension was significantly higher in the asbestosis group (42.3 mm Hg) than in the other three groups.
  • Carbon monoxide transfer factor and oxygen ductance were significantly lower in all three exposed groups than in the non-exposed workers.
  • Workers with asbestosis had significantly lower mean FVC and FEV1 than the healthy exposed and non-exposed groups.
  • Exercise breathlessness was reported by 1 of 9 non-exposed men, compared with 8 of 9 healthy exposed, 8 of 10 with plaques and 9 of 11 with asbestosis (P less than 0.001). Differences in chronic phlegm were not significant.
  • Adding smoking to the analysis showed no difference in any measured variable that could be attributed to smoking, in a sample where no worker had smoked more than 10 pack-years.
  • In 6 subjects retested after two months, repeat mucociliary clearance measurements correlated highly (r 0.955).
• The authors' conclusion: The authors concluded that the results seem to confirm that cinescintigraphy can feasibly be used to study mucociliary function and bronchiolar-alveolar patency in vivo in asbestos cement workers. They also stated that only the cinescintigraphic variables and arterial carbon dioxide values distinguished the asbestosis group from the pleural plaque group.
• Limitations the authors state:
  • Variability within subjects on repeat testing means the method needs fuller evaluation with more subjects.
  • An irritant effect of the cement dust itself on the airways could not be excluded, although the authors argued most cement particles are too large to reach the small airways studied.

Topics

Medical terms in this study, explained in our Lexicon: Mucociliary Clearance, Asbestos-Cement, Chest X-Ray, Spirometry, Deposition, Alveoli, Pleural Plaques, Habit.

Related studies

• Rapid short-term clearance of chrysotile compared with amosite asbestos in the guinea pig — A. Churg, J.L. Wright, et al. (1989)
• Lung function in relation to radiographic changes in asbestos workers — S. Zedda, G. Aresini, et al. (1973)
• Studies on the deposition of inhaled fibrous material in the respiratory tract of the rat and its subsequent clearance using radioactive tracer techniques. 1. UICC crocidolite asbestos — J.C. Evans, R.J. Evans, et al. (1973)
• Regional lung function in asbestos workers: observations and speculations — R.H. Secker-Walker, J.E. Ho (1982)
• Bronchoalveolar lavage and 99mTc-DTPA clearance as prognostic factors in asbestos workers with and without asbestosis — N. al Jarad, A.R. Gellert, et al. (1993)
• Early lung events following low-dose asbestos exposure — R. Bégin, M. Rola-Pleszczynski, et al. (1981)

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