2020 Volume 24 Issue 3 Pages 217-230
Purpose: The purpose of this study was to evaluate the coordination between swallowing and respiration during noninvasive positive pressure ventilation (NPPV), and clarify the safe swallowing volume and method.
Methods: The subjects consisted of 28 nurses (11 males and 17 females) aged 36.0±5 years (mean). The independent variables were the swallowing volume (5 or 10 mL), NPPV (during or without), and the swallowing method (voluntary or according to instructions), and their combinations were analyzed. For swallowing according to instructions, the subjects were instructed to swallow after inspiration. The dependent variables were the incidences of respiration patterns during swallowing, respiratory cessation during preparation before and after swallowing, and inspiration after swallowing apnea, as well as respiratory cycle duration before swallowing, swallowing apnea duration, respiratory cycle duration related to swallowing during NPPV, and the presence of forced ventilation.
During swallowing, respiration data were obtained using a Piezo Respiratory Belt Transducer® with simultaneous surface electromyography of the suprahyoid muscles. For NPPV, Trilogy 100® and oronasal masks were used. The subjects were placed in the supine position with a 30°head-up tilt on the bed. Water was injected into the oral floor using an 8-Fr feeding catheter, and the subjects were asked to swallow it.
Water (5 and 10 mL) was swallowed three times under each of the following conditions: voluntary swallowing without NPPV, voluntary swallowing during NPPV, and swallowing according to instructions during NPPV (total number of swallows: 18 times).
Results: 1. In voluntary swallowing during NPPV compared with that without NPPV, the incidence of the inspiration-apnea-expiration (iae) pattern increased, and the respiration cycle duration before swallowing was significantly prolonged irrespective of the water volume.
2. In swallowing according to instructions during NPPV compared with voluntary swallowing during NPPV, the incidence of the iae pattern increased irrespective of the water volume. In addition, inspiration after swallowing as a respiration pattern was not observed. However, the incidence of respiratory cessation during preparation before swallowing was high.
3. In swallowing according to instructions during NPPV compared with voluntary swallowing without NPPV, the respiratory cycle duration before swallowing and that related to swallowing during NPPV were significantly prolonged.
Discussion: In voluntary swallowing during NPPV, the incidence of the iae pattern was high irrespective of the water volume. It may be important for safer swallowing to instruct patients to swallow just at the end of inspiration and then expire immediately during NPPV.
