Airflow Pattern Complexity in Asbestos-Exposed Workers: Effect of Smoking and Diagnostic Accuracy

Abstract

We evaluated the effect of exposition to asbestos in the complexity of the respiratory system investigating the airflow pattern sampling entropy (SamEnV′), recurrence period density entropy (RPDEV′) and variability (SDV′). A non-invasive and simple protocol for assessing respiratory mechanics during spontaneous breathing was used in a group of 30 controls and 29 asbestos-exposed patients. Exposition resulted in a significant reduction in the RPDEV′ (p < 0.001) and an increase in SDV′ (p < 0.001). These results suggest that the airflow pattern becomes less complex in exposed patients, which may explain the reduction in respiratory systems’ adaptability to daily life activities. The influence of smoking was also investigated in exposed patients, which resulted in a significant reduction in SamEnV′ (p < 0.03). This suggests a further abnormal effect in smokers. Diagnostic accuracy evaluations indicate that RPDEV′ and SDV′may contribute to the diagnosis of respiratory abnormalities in asbestos-exposed patients with accuracies of 76.9 and 78.8%, respectively. As measuring airflow pattern complexity during tidal breathing is simple method, requiring only the passive cooperation, this technique may constitute a significant clinical contribution by providing novel respiratory biomarkers to facilitate the diagnosis of respiratory abnormalities these patients.