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

Abstract

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