Small Airway Dysfunction and Abnormal Exercise Responses. A Study in Coal Miners.

RATIONALE: Coal mine dust exposure can cause symptoms and loss of lung function from multiple mechanisms, but the roles of each disease process are not fully understood. OBJECTIVES: We investigated the implications of small airway dysfunction for exercise physiology among a group of workers exposed to coal mine dust. METHODS: Twenty coal miners performed spirometry, first breathing air and then helium-oxygen, single-breath diffusing capacity, and computerized chest tomography, and then completed cardiopulmonary exercise testing. MEASUREMENTS AND MAIN RESULTS: Six participants meeting criteria for small airway dysfunction were compared with 14 coal miners who did not. At submaximal workload, miners with small airway dysfunction used a higher proportion of their maximum voluntary ventilation and had higher ventilatory equivalents for both O2 and CO2. Regression modeling indicated that inefficient ventilation was significantly related to small airway dysfunction but not to FEV1 or diffusing capacity. At the end of exercise, miners with small airway dysfunction had 27% lower O2 consumption. CONCLUSIONS: Small airway abnormalities may be associated with important inefficiency of exercise ventilation. In dust-exposed individuals with only mild abnormalities on resting lung function tests or chest radiographs, cardiopulmonary exercise testing may be important in defining causes of exercise intolerance.

Prevalence of Airflow Obstruction in U.S. Adults Aged 40-79 Years: NHANES Data 1988-1994 and 2007-2010.

BACKGROUND: The study evaluated the change in the prevalence of airflow obstruction in the U.S. population 40-79 years of age from years 1988-1994 to 2007-2010. METHODS: Spirometry data from two representative samples of the U.S. population, the National Health and Nutrition Examination Surveys (NHANES) conducted in 1988-1994 and 2007-2010, were used. The American Thoracic Society/European Respiratory Society (ATS/ERS) criteria were used to define airflow obstruction. RESULTS: Based on ATS/ERS criteria, the overall age-adjusted prevalence of airflow obstruction among adults aged 40-79 years decreased from 16.6% to 14.5% (p < 0.05). Significant decreases were observed for the older age category 60-69 years (20.2% vs. 15.4%; p < 0.01), for males (19.0% vs. 15.4%; p < 0.01), and for Mexican American adults (12.7% vs. 8.4%; p < 0.001). The prevalence of moderate and more severe airflow obstruction decreased also (6.4% vs. 4.4%; p < 0.01). Based on ATS/ERS criteria, during 2007-2010, an estimated 18.3 million U.S. adults 40-79 years had airflow obstruction, 5.6 million had moderate or severe airflow obstruction and 1.4 million had severe airflow obstruction. CONCLUSIONS: The overall age-adjusted prevalence of airflow obstruction among U.S. adults aged 40-79 years decreased from 1988-1994 to 2007-2010, especially among older adults, Mexican Americans, and males.

Lung-function impairment among US underground coal miners, 2005 to 2009: geographic patterns and association with coal workers' pneumoconiosis.

OBJECTIVE: To investigate contemporary geographic distributions of lung-function impairment and radiographic evidence of coal workers' pneumoconiosis (CWP) and their associations. METHODS: From 2005 to 2009, 6373 underground coal miners completed a health survey, including spirometry testing and chest radiography. Coal workers' pneumoconiosis and progressive massive fibrosis were determined by NIOSH B readers, using the International Labour Office classification. Prevalences of CWP and spirometry less than lower normal limits were mapped by county, and their association assessed. RESULTS: The prevalences of abnormal spirometry results and CWP were 13.1% and 4.0%, respectively. Counties with elevated prevalences for both the outcomes were located in contiguous areas of southeastern Kentucky, western Virginia, southern West Virginia, and eastern Pennsylvania. Prevalence of abnormal spirometry results increases with increasing category of simple CWP and progressive massive fibrosis. CONCLUSIONS: Abnormal spirometry in coal miners is associated with CWP; these two health outcomes have similar geographic distributions.

Rapid decline in lung function in coal miners: evidence of disease in small airways.

BACKGROUND: Coal mine dust exposure can cause both pneumoconiosis and chronic airflow limitation. The contributions of various pathophysiologic mechanisms to dust-related lung function decrements remain unclear. METHODS: Clinical and physiological findings were assessed for 15 underground coal miners who had demonstrated accelerated FEV1 losses (decliners) over 6-18 years. Decliners' findings were evaluated in comparison to a group of 11 miners who had shown relatively stable lung function (referents) during the same period. RESULTS: At follow-up examination, the decliners showed significantly greater mean airway resistance (10.47 vs. 6.78 cmH2 O/L/s; P = 0.05) and more air trapping (RV/TLC = 37.5 vs. 29.1%; P < 0.01) compared to the referents. Decliners also demonstrated more evidence of small airways dysfunction and tended to have more bronchospasm than the referent group. Total lung capacity, lung compliance, diffusing capacity, and chest radiography did not differ significantly between the two groups. After cessation of mine dust exposures, the decliners' mean rate of FEV1 loss normalized. CONCLUSION: In a series of working coal miners, accelerated lung function declines were associated with air trapping and evidence of small airways dysfunction. A preventive benefit from controlling dust exposures was suggested.

Periodic spirometry in occupational setting: improving quality, accuracy, and precision.

OBJECTIVE: Effectiveness of periodic spirometry in medical monitoring depends on spirometry quality. We describe an intervention on spirometry quality and its impact on accuracy and precision of longitudinal measurements. METHODS: The intervention was conducted from 2005 to 2010 in a monitoring program involving approximately 2500 firefighters. Intervention supported adherence to 2005 American Thoracic Society/European Respiratory Society recommendations through monitoring of spirometry quality and longitudinal data precision, technician training, change of spirometer, and quality control. RESULTS: The percentage of forced vital capacity tests meeting the American Thoracic Society/European Respiratory Society criteria increased from 60% to 95% and the mean longitudinal forced expiratory volume in 1 second within-person variation decreased from 6% to 4%. The increased accuracy and precision of measurements and estimated rates of forced expiratory volume in 1 second decline were statistically significant. CONCLUSION: Monitoring of quality and data precision helped to recognize the need for intervention. The intervention improved accuracy and precision of spirometry measurements and their usefulness.

Worksite wellness program for respiratory disease prevention in heavy-construction workers.

OBJECTIVE: To describe a respiratory disease prevention program in a US heavy-construction company. METHODS: The program uses periodic spirometry and questionnaires and is integrated into a worksite wellness program involving individualized intervention. Spirometry Longitudinal Data Analysis (SPIROLA) technology is used to assist the physician with (i) management and evaluation of longitudinal spirometry and questionnaire data; (ii) designing, recoding, and implementing intervention; and (iii) evaluation of impact of the intervention. Preintervention data provide benchmark results. RESULTS: Preintervention results on 1224 workers with 5 or more years of follow-up showed that the mean rate of FEV1 decline was 47 mL/year. Age-stratified prevalence of moderate airflow obstruction was higher than that for the US population. CONCLUSION: Preintervention results indicate the need for respiratory disease prevention in this construction workforce and provide a benchmark for future evaluation of the intervention.

Spirometry Longitudinal Data Analysis Software (SPIROLA) for Analysis of Spirometry Data in Workplace Prevention or COPD Treatment.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality. Periodic spirometry is often recommended for individuals with potential occupational exposure to respiratory hazards and in medical treatment of respiratory disease, to prevent COPD or improve treatment outcome. To achieve the full potential of spirometry monitoring in preserving lung function, it is important to maintain acceptable precision of the longitudinal measurements, apply interpretive strategies that identify individuals with abnormal test results or excessive loss of lung function in a timely manner, and use the results for intervention on respiratory disease prevention or treatment modification. We describe novel, easy-to-use visual and analytical software, Spirometry Longitudinal Data Analysis software (SPIROLA), designed to assist healthcare providers in the above aspects of spirometry monitoring. Software application in ongoing workplace spirometry-based medical monitoring programs helped to identify increased spirometry data variability due to deteriorating test quality and subsequent improvement following interventions, and helped to enhance identification of individuals with excessive decline in lung function.