Abstract
Cervical auscultation (CA) is used frequently in the clinical assessment of dysphagia. Abnormal swallowing and respiratory sounds during dysphagic swallows can be heard by cervical auscultation. However, assessment by CA is based on subjective evaluation. This study was designed to evaluate quantitatively the swallowing and expiratory sounds for distinguishing dysphagic swallows from normal swallows.
Fourteen glossectomized patients were examined. Patients swallowed 5 ml of barium several times. The swallowing and expiratory sounds were detected and recorded with videofluorographic (VF) images of these swallows and expiratory events. From the VF data, the analyzed sounds were classified into three groups ; Safety (sounds produced during safe swallows), WA (sounds produced during swallows with aspiration) and WP (with penetration). The mean durations of the swallowing sounds of WA (9.01 sec) and WP (12.06 sec) were significantly longer than that of Safety (0.60 sec). Comparison of the differentiation using the critical duration with the VF data (Safety/WA or WP) showed significant agreement in both areas. In the frequency domain analysis, the averaged magnitude of each frequency band from 0 to 1000 Hz of the expiratory sounds of WA and WP were significantly greater than those of Safety. Comparison of the differentiation using the critical magnitude of a frequency band from 0 to 250 Hz of the expiratory sounds with the VF data showed significant agreement in both areas. These results suggest that acoustic characteristics of the swallowing and expiratory sounds can be used as a clinical tool for detecting dysphagic swallows.
