Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos-induced fibrosis

Our plain-English summary of Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos-induced fibrosis, by J. Schneider, R. Arhelger, M. Funk (The Clinical Respiratory Journal, 2014).

The study

• Authors: J. Schneider, R. Arhelger, M. Funk
• Journal: The Clinical Respiratory Journal
• Published: 2014;8(2):175-84
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Exercise intolerance is typical for asbestosis. We examined the correlation of spiroergometric parameters with severity of asbestosis according to the International Labour Office (ILO) classification. Patients were compared to a healthy control group.

Objectives: Nineteen consecutive male patients with compensated asbestosis and 24 healthy subjects were examined.

Methods: All participants underwent pulmonary functional testing including maximal cardiopulmonary exercise testing (CPET). Results were compared to those of healthy subjects; the correlation to disease status was investigated.

Results: Significantly lower VCin , FVC, FEV1 , MEF50 , TLC and PaO2 at rest (P<0.001) were observed in asbestosis patients. Lower peak (weight-related) work rate (WR, WR/kg), (weight-related) oxygen uptake (V'O2 , V'O2 /kg), oxygen pulse (V'O2 /hr), ventilation volume (V'E ), carbon dioxide output (V'CO2 ) and blood lactate was associated (P<0.001) with more severe asbestosis according to the ILO-classification. Significant positive correlations (P<0.001) were seen for alveolar-arterial oxygen difference [P(A-a)O2 ] and PaCO2 . Multiple regression analysis revealed that asbestosis was the only significant factor associated with the spiroergometric parameters (P<0.001). A reduction of V'O2 , V'O2 /kg, V'O2 /hr, V'E , or V'CO2 at identical submaximal workload could neither be detected among the asbestosis severity nor in comparison to healthy subjects. Only the respiratory frequency was depending on severity of asbestosis.

Conclusions: The severity of asbestosis correlates with maximal WR, V'O2 , V'O2 /hr, V'E and gas exchange. At identical workload the discrimination between patients and controls was only possible concerning the respiratory frequency. For detection of limitations in asbestosis patients, maximal CPET is recommended.

© 2013 John Wiley & Sons Ltd.

In plain English

This German study compared exercise test results in 19 men with compensated asbestosis (lung scarring from asbestos) with 24 healthy men aged 60 to 79. The patients came from 320 formerly asbestos-exposed people seen at a Giessen outpatient clinic over five years. Thirteen had X-ray scarring graded ILO 1/1 and 6 had more severe grades. All did lung function tests and a maximal cycling test. At peak exercise, patients reached lower work rates than healthy men: a mean of 88.5 watts in the milder group and 75.0 in the more severe group, versus 149. Patients also had lower oxygen uptake. Higher X-ray grades were associated with lower peak work rate (r=-0.73), lower oxygen uptake (r=-0.72) and a larger alveolar-arterial oxygen difference (r=0.747). The authors allowed for age, body size, smoking, pleural plaques and airway disease. After that, each step in X-ray grade was linked to 7.2 watts less peak work. At equal, below-peak workloads, only breathing rate was higher in patients. The authors noted wide overlap between groups. They concluded that maximal exercise testing is recommended to detect limitations in asbestosis patients.

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: Comparison study: patients with asbestosis tested with lung function tests and maximal cardiopulmonary exercise testing, compared with a healthy control group, with correlation and multiple regression analyses
• Who was studied: 19 consecutive men with compensated asbestosis (ILO profusion 1/1, n=13; greater than 1/1, n=6), drawn from 320 people with former occupational asbestos exposure examined over a 5-year period at an outpatient clinic in Giessen, Germany. They were compared with 24 healthy men recruited from the local population for a reference-value study of people aged 60-79. Pleural plaques were present in 8 (62%) of the ILO 1/1 group and 3 (50%) of the more severe group.
• Exposure: Occupational asbestos exposure in Germany before the asbestos ban. Fiber types were not reported. Main exposures included sprayed asbestos or mats as insulators (n=3), pipe fitters in power utilities (n=5), asbestos cement production, building trades, asbestos paper and textile production, foundry work and rubber industry (n=2). Cumulative exposure was estimated from self-reported work histories: mean 78.9 plus or minus 76.9 fiber-years in the ILO 1/1 group and 362.5 plus or minus 570.0 in the more severe group.
• Main results:
  • Mean peak work rate was 149 plus or minus 32 watts in healthy subjects, 88.5 plus or minus 21.9 in ILO 1/1 patients and 75.0 plus or minus 15.8 in ILO greater than 1/1 patients. Both patient groups differed from controls at p less than 0.001. Peak oxygen uptake was 2221, 1482 and 1267 ml/min respectively.
  • Patients with ILO profusion greater than 1/1 had significantly lower weight-related peak work rate than those with ILO 1/1 (p=0.029).
  • Higher ILO profusion was associated with lower maximal work rate (r=-0.73), weight-related work rate (r=-0.691) and oxygen uptake (r=-0.72), all p less than 0.001.
  • The alveolar-arterial oxygen difference correlated positively with asbestosis stage (r=0.747; p less than 0.001).
  • After controlling for age, height, weight, BMI, pack-years, pleural plaques and obstructive or emphysematous lung function patterns, each ILO profusion step was associated with an average decrease of 7.2 watts in work rate, 81.2 ml/min in oxygen uptake, 0.335 in oxygen pulse and 87.5 ml/min in carbon dioxide output, and an increase of 2.9 mmHg in the alveolar-arterial oxygen difference. Severity of asbestosis was the only significant factor.
  • Cumulative fiber-years did not show a significant effect in the regression models.
  • At identical submaximal workloads, oxygen uptake did not differ between patients and healthy subjects. Only respiratory frequency was higher, depending on asbestosis severity.
• The authors' conclusion: The authors concluded that the ILO classification reflects patients' maximal exercise capacity and gas exchange, and that maximal cardiopulmonary exercise testing is recommended for broader and more reliable detection of limitations in asbestosis patients.
• Limitations the authors state:
  • Spiroergometric variables varied widely, so the groups overlapped and potential differences were hard to detect.
  • Because of the wide range of ventilation parameters, no significant differences could be detected between the two asbestosis groups.
  • Because of impaired exercise tolerance, lactate values in asbestosis patients could not be regarded as appropriate.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Fibrosis, FEV1.

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• Exercise training for asbestos-related and other dust-related respiratory diseases: a randomised controlled trial — M.T. Dale, Z.J. McKeough, et al. (2014)
• Effect of induction chemotherapy on lung function and exercise capacity in patients affected by malignant pleural mesothelioma — G. Marulli, F. Rea, et al. (2010)
• Functional exercise capacity and health-related quality of life in people with asbestos related pleural disease: an observational study — M.T. Dale, Z.J. McKeough, et al. (2013)
• Factors influencing exercise performance in thoracic cancer — R. England, M. Maddocks, et al. (2012)

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