Computerised acoustical respiratory phase detection without airflow measurement

A simple, non-invasive acoustical method is developed to detect respiratory phases in relationship to swallows without the direct measurement of airfl ow. In 21 healthy subjects (4-51 years) breath sounds are recorded at the t rachea and at five different recording locations at the chest wall, with si multaneous recording of airflow by a pneumotachograph. The chest signal wit h the greatest inspiratory-expiratory power difference ('best location') is either in the mid-clavicular line in the second interspace on the left or third interspace on the right. Using the 'best location' on the chest wall and the tracheal signal, a phase detection algorithm is developed and achie ves 100% accuracy in the estimation of respiratory phases without using the measured airflow signal. Thus, acoustically monitoring breaths and swallow s holds promise as a non-invasive and reliable assessment tool in the study of swallowing dysfunction.