Effects of noninvasive ventilation on the coordination between breathing and swallowing in patients with chronic obstructive pulmonary disease

Purpose: As shown in our previous study, inspiration after swallowing (SW-I) increases during the bi-level positive airway pressure ventilation (BiPAP) in healthy subjects because swallowing-associated non-inspiratory flow (SNIF) triggers inspiratory support, while SW-I during continuous positive pressure ventilation (CPAP) is rare. In the present study, we evaluated the coordination between breathing and swallowing during spontaneous breathing, BiPAP, and CPAP in patients with chronic obstructive pulmonary disease (COPD).

Patients and methods: This study is a prospective intervention study at the Hoshigaoka Medical Center (November 01, 2015-April 30, 2018). We simultaneously recorded the respiratory flow, laryngeal motion, and swallowing sounds during saliva swallowing in patients with COPD. We estimated the respiratory phase after swallowing, frequency of SNIF, the duration of the respiratory pause during swallowing, and timing of swallowing in the respiratory cycle and compared these parameters among control, CPAP, and BiPAP conditions.

Results: The expiration after swallowing (SW-E) frequency was associated with the occurrence of SNIF (p<0.01), pause duration ≤0.8 s (p<0.01), and timing of swallowing at the intermediate respiratory phase (50-80% of the respiratory cycle from the onset of inspiration) (p<0.01). In particular, the occurrence of SNIF most substantially affected the SW-E frequency. The SW-I frequencies under the control, CPAP, and BiPAP conditions were 35.0%, 3.0%, and 37.7%, respectively. The pause durations were shorter during CPAP and BiPAP than under the control condition (p<0.01). During CPAP, the occurrence rates of SW-E. Residual denotes the percentage difference between observed and expected values (residual =10.8: p<0.01) and SNIF (residual =9.1: p<0.01) were significantly increased, and timing of swallowing shifted toward the intermediate respiratory phase (residual=3.5: p<0.01).

Conclusion: CPAP decreases the SW-I frequency, increases the SNIF occurrence, and normalizes the timing of swallowing, all of which suggest that CPAP alleviates the risk of aspiration in patients with COPD.