Evaluation of an EMG bioimpedance measurement system for recording and analysing the pharyngeal phase of swallowing

A neuroprosthetic device for treating swallowing disorders requires an implantable measurement system capable to analysing the timing and quality of the swallowing process in real time. A combined EMG bioimpedance (EMBI) measurement system was developed and is evaluated here. The study was planned and performed as a case–control study. The studies were approved by the Charité Berlin ethics committee in votes EA1/160/09 and EA1/161/09. Investigations were carried out on healthy volunteers in order to examine the usefulness and reproducibility of measurements, the ability to distinguish between swallowing and head movements and the effect of different food consistencies. The correlation between bioimpedance and anatomical and functional changes occurring during the pharyngeal phase of swallowing in non-healthy patients was examined using videofluoroscopy (VFSS). 31 healthy subjects (15♂, 16♀) were tested over the course of 1350 swallows and 19 (17♂, 2♀) non-healthy patients over the course of 54 swallows. The signal curves obtained from both transcutaneous and subcutaneous measurement were similar, characteristic and reproducible (r > 0.5) and correlated with anatomical and functional changes during the pharyngeal phase of swallowing observed using VFSS. Statistically significant differences between head movements and swallowing movements, food volumes and consistencies were found. Neither the conductivity of the food, the sex of the test subject nor the position of the measurement electrodes exerted a statistically significant effect on the measured signal. EMBI is able to reproducibly map the pharyngeal phase of swallowing and changes associated with it both transcutaneously and subcutaneously. The procedure therefore appears to be suitable for use in performing automated evaluation of the swallowing process and for use as a component of an implant.