Disturbances in airflow dynamics and tracheal sounds during forced and quiet breathing in subjects with unilateral vocal fold paralysis

Variable extra thoracic obstruction has been found in spirometric studies i n subjects with unilateral vocal fold paralysis. The aim of the study was t o further evaluate airflow dynamics in these subjects with body plethysmogr aphy and tracheal sound analysis. Ten patients with unilateral vocal fold p aralysis without a history of chronic pulmonary diseases and 10 healthy con trol subjects were studied. Flow-volume spirometry, body plethysmography an d tracheal sound analysis were performed within 1 day. The study shows that peak inspiration, flow (PIF) and specific airway conductance (SG(aw)) expr essed as percentage of Finnish reference values were significantly lower an d airway resistance (R-aw) was higher among the patients than among the con trols (P = 0.004, P = 0.026 and P = 0.004, respectively). The patients had higher sound amplitude of both inspiration, and expiratory tracheal sounds than the controls [root mean square (RMS) values of the power spectra were 31.5 and 25 dB, P = 0.006 in inspiration and 31.5 and 26 dB, P = 0.013 in e xpiration, respectively]. Quartile frequencies (F25 and F50) and RMS of exp iratory tracheal sounds had significant negative correlation with PIT (P = 0.02, P<0.001, P = 0.02, respectively) and forced inspiratory volume in 1 s (FIV1) (P = 0.01, P<0.001, P = 0.01, respectively). There was also an asso ciation between F50 and peak expiratory flow (PEF) (P = 0.02). According to the present study, both quiet breathing and forced inspiration are disturb ed in subjects with unilateral vocal fold paralysis. A close relationship b etween tracheal sounds and respiratory function tests exists.