Coordination of swallowing and respiration in normal sequential cup swallows

Objectives: To establish normative data on laryngeal vestibular closure patterns and respiratory phase patterns during sequential cup swallows in healthy adults. Study Design: Cross-sectional study. Methods. Combined videofluoroscopic and respiratory phase recordings were analyzed in 70 healthy adults during 50 mL sequential liquid cup swallows. The following dependent variables were measured offline from the digitized recordings: 1) number of swallows, 2) number of ingestion cycles (IC) (period of sustained apnea including 1 or more swallows), 3) opening of the laryngeal vestibule after each swallow, and 4) respiratory phase surrounding each IC. Patients were grouped according to the position of the larynx after each swallow. Results: The mean number of swallows was 4.35, and the mean number of ICs was 3.28. Laryngeal vestibular opening after swallows was categorized into three groups: Always Open = 67.1%, Mixed (Open and Closed) = 31.4%, Always Closed = 1.4%. Statistical differences were not found in laryngeal opening pattern by age or sex, but the Always Open group had fewer swallows (4.02 vs. 5.23, P=.008) and a greater number of ICs (3.62 vs. 2.41, P=.001) than the Mixed Group. Respiratory phase after IC was expiration in 79% and inspiration in 21%. Conclusions: Normal patterns of laryngeal vestibular closure and respiratory phase coordination during sequential swallowing have been described for the first time. The high occurrence of inspiration and laryngeal vestibular opening that surrounds sequential liquid cup swallows when compared with previous findings in single, discrete swallows may place patients with swallowing disorders at greater risk during this task.