Effects of age, gender, bolus volume and bolus consistency on swallowing parameters and on temporal coordination of breathing and swallowing in normal adults

Background: The temporal coordination of respiration and swallowing is provided by an extended pontomedullary neuronal network. However, it is not well known which factors influence swallowing parameters and the breathing pattern during normal swallowing. Methods: The study included 60 healthy subjects, median age 49y. A 2-channel computer assisted system was used to obtain concurrent respiratory and submental surface electromyography signals. Subjects were seated in an upright position and asked to swallow a bolus of 5,10, 25ml water and 5ml applesauce presented in random order. Eight swallows of each bolus volume and viscosity were recorded. For each swallow, the (1) latency between the onset of swallowing and swallowing apnea (SA), (2) duration of swallowing, (3) duration of SA, and (4) pattern of breathing after each SA were evaluated. Results: In healthy subjects a total of 3.360 swallows were performed. The main finding was a significant prolongation of all swallowing parameters (latency between the onset of swallowing and SA, duration of swallowing and duration of SA) (ANOVA, p<0.0001) with age in all bolus volumes of water but not with a higher bolus consistency. Increasing bolus volumes led to a significant increase of the duration of swallowing and SA (ANOVA, p<0.01). Gender influenced none of the parameters. Inspiration after SA occurred in 1.9% of all swallows and was not significantly affected by age, gender and bolus variables. Conclusion: Our study demonstrated a strong influence of age and bolus volume on all swallowing parameters when swallowing water. However, age, gender and all bolus variables did not influence the temporal coordination of breathing and swallowing, which is relevant for airway protection from aspiration during swallowing. Supported by MAIFOR.