Involvement of the aero-digestive tract in swallowing-ventilation coordination: an animal study.

BACKGROUND

The precise coordination of swallowing and ventilation is considered an important mechanism for minimizing the risk of pulmonary aspiration. The aim of this study was to test the hypothesis that the aero-digestive tract is involved in swallowing-ventilation coordination in rats.

METHODS

The goal of the first part of the study was to characterize swallowing events associated with ventilation signals obtained using a barometric plethysmograph. This was done in seven rats with the help of esophageal electromyograms. Thereafter, swallowing-ventilation coordination was assessed in 15 rats with right unilateral vocal cord paralysis and 10 rats following oropharyngeal anesthesia.

KEY

RESULTS

In healthy animals, 92 ± 11% of swallows occurred during expiration and 8 ± 11% during inspiration. Swallow frequency and swallowing characteristics based on ventilation did not change following unilateral laryngeal paralysis. Swallows during expiration decreased (71 ± 9%, P < 0.01) while swallows during inspiration increased (29 ± 11%, P < 0.01) following oropharyngeal anesthesia with lidocaine.

CONCLUSIONS & INFERENCES: Our findings using a rat model need to be confirmed, however, they indicated that a rat model can be used to study oropharyngeal dysphagia and that laryngo-pharyngeal anesthesia alters swallowing-ventilation coordination.