Respiratory health screening using pulmonary function tests and lung sound analysis

Lung sounds (LS) analysis is a potential source of additional objective, noninvasive and quantitative information on the status of the pulmonary system. We have examined the hypothesis that the addition of lung sounds analysis to spirometry increases the sensitivity of objective population screening, as compared to the use of spirometry alone. Questionnaires, spirometry and lung sounds were obtained in 493 active workers. Lung sounds analysis consisted of the averaged power spectra of breath sounds, measured separately during inspiration and expiration at four standard locations over the trachea and the chest-wall. Of the 493 subjects, 91 had an obstructive lung disease, including 27 with chronic bronchitis identified by a history of prolonged cough and sputum production but with normal spirometry. Twelve additional workers had a restrictive lung disease. Abnormal spirometric results were found in 74 of the patients. Abnormal lung sounds analyses were found in 54 patients, including 14 of the chronic bronchitis cases, so that the overall sensitivity of objective screening tests increased from 71% to 87% by combining the two tests. Thirty three of the subjects considered normal by evaluation of their questionnaire and spirometry had abnormal lung sounds. Of the twenty four who were re-evaluated 12-18 months after the first tests, three had developed a lung or heart disease. We conclude that the combination of spirometry and lung sounds analysis significantly increased the sensitivity of detection of pulmonary diseases by objective tests, and provided an early sign of lung disease that was not detected by spirometry alone.