Differences in the swallowing process of newborns and healthy preterm infants: first results with a non-invasive bioimpedance and electromyography measurement system.

PURPOSE: Preterm infants (PI) have difficulty coordinating sucking, swallowing and breathing, and there is a risk of aspiration. The causes of this are not yet sufficiently understood. The aim of this study was to test a novel measurement device to measure breathing and pharyngeal processes involved in swallowing externally in everyday life to identify possible differences in neonates (NB) and PI. METHODS: Forty healthy NB were studied at 4-8 weeks of age (mean: 6.7 weeks) and 20 healthy PI (mean gestational age 30.5 weeks) at postmenstrual age (PMA) 34/35 weeks (mean PMA 35.1 weeks) during a single feeding. Surface electrodes were used to measure bioimpedance and electromyography reflecting swallow-related changes in the pharynx and muscle activation of the tongue and submental muscles. A respiratory belt was combined with recording of the depth of chest movements and the occurrence of pauses in breathing. RESULTS: Velocity and extent of pharyngeal closure did not differ significantly across the feeding period (velocity: p=0.09, closure: p=0.17), but during the first two suck-swallow bursts PI had greater velocity (p<0.001*) and extent of pharyngeal closure (p=0.004*) than NB. The duration of swallowing phases was significantly longer in PIs (p<0.001*), their muscle activation decreased faster (p<0.001*), and they had more pauses in breathing than NBs. CONCLUSIONS: The novel measurement device allowed, for the first time in everyday life, the measurement of factors influencing swallowing and breath-swallow coordination in NBs and PIs. PIs showed differences from NBs most likely due to differences in muscle strength and condition.

Multisensor Classification System for Triggering FES in Order to Support Voluntary Swallowing.

In dysphagia the ability of elevating the larynx and hyoid is usually impaired. Electromyography (EMG) and Bioimpedance (BI) measurements at the neck can be used to trigger functional electrical stimulation (FES) of swallowing related muscles. Nahrstaedt et al.1 introduced an algorithm to trigger the stimulation in phase with the voluntary swallowing to improve the airway closure and elevation speed of the larynx and hyoid. However, due to non-swallow related movements like speaking, chewing or head turning, stimulations might be unintentionally triggered. So far a switch was used to enable the BI/EMG-triggering of FES when the subject was ready to swallow, which is inconvenient for practical use. In this contribution, a range image camera system is introduced to obtain data of head, mouth, and jaw movements. This data is used to apply a second classification step to reduce the number of false stimulations. In experiments with healthy subjects, the amount of potential false stimulations could be reduced by 47% while 83% of swallowing intentions would have been correctely supported by FES.