A novel system using the Forced Oscillations Technique for the biomechanical analysis of swallowing

Physiological studies of swallowing and the diagnosis and treatment of dysphagia are crucially dependent of detailed information of respiratory and feeding events. However, this information has been obtained by indirect and/or expensive methods, as well as by methods demanding exposure to radiation. In this context, the purpose of this study was twofold: (1) describe a new low-cost system for the analysis of the respiratory events during swallowing using the Forced Oscillation Technique and (2) evaluate the performance of this device in the description of physiological events during water swallowing. The device consists of a personal computer adapted to measurement modules able to characterize the soft palate movement, the elevation of the larynx, the duration of deglutition apnoea, and the direction of airflow at the end of the swallow apnoea. These parameters were studied in eight healthy subjects under conditions of saliva swallowing and three doses of water (5,10 and 20 mL). The system allowed a real time description of the respiratory and feeding events, which were in close agreement with physiological principles. Mean results showed an increase of the apnoea time that was not statistically significant. In contrast, a highly significant increase of respiratory impedance during swallowing was observed (p < 0.0001). The described instrument does not use radiation. It shows itself particularly well suited for studies of deglutition physiology, including mechanisms involved in airway protection during swallowing. It can also be potentially useful contributing to easy clinical bedside evaluations and biofeedback procedures for the rehabilitation of paediatric and elderly patients.