Differentiating Effortful and Noneffortful Swallowing with a Neck Force Transducer: Implications for the Development of a Clinical Feedback System

Abstract

This study sought to determine whether effortful saliva swallows could be differentiated from habitual, noneffortful saliva swallows on the basis of swallow-related changes in neck circumference in humans. Gender differences in swallow-related neck circumference were examined as a secondary question. Twenty-seven healthy adults (14 females; mean age = 26.6 years, SD = 3.9 years) participated in two experimental runs (run duration = 10 min) during which they produced single trials of three visually cued tasks in random order: effortful saliva swallowing, saliva swallowing, and a control task involving repetitive apposition of the dominant thumb and index finger. Neck and ribcage circumference were simultaneously collected from the output of force transducers positioned around the neck and ribcage, respectively. The primary outcome variables were the positive and negative voltage peak amplitudes associated with changes in neck circumference during single-swallow trials. Effects of the swallowing task on positive and negative voltage peaks were examined with separate two-way analysis of variance procedures. Results indicated that both positive (F = 6.49, p < 0.05) and negative (F = 12.05, p <or= .05) voltage peaks were significantly greater for effortful swallows compared with those for noneffortful swallows. The gender main effect and the swallow type by gender interaction were not significant. Effortful and noneffortful swallows of saliva can be differentiated from the output of a noninvasive force transducer worn around the neck. This type of physiologic recording may have potential as a biofeedback technique in training dysphagic patients on the effortful swallow maneuver.