In search of a longitudinal animal model of evoked swallow function

Abstract

Background: A malfunction or impairment of swallow function can potentiate aspiration events and interfere with both quality of life and survival. Establishing an animal model for swallow research would provide a better understanding of its pathophysiology and would also allow for the development and validation of physiologically based clinical interventions to improve swallow function. Two requirements define the ideal model for longitudinal exploration: 1) identification of species similar to human in form and function; and 2) provision for reliable and reproducible evoked swallow under general anesthesia and one that would also support a longitudinal study design. Objective: We hypothesize that an anesthetized porcine model under dexmedetomidine-based or ketamine-based anesthesia will support a reproducible and stable evoked swallow response. Methods: Seven neutered male Yorkshire pigs were anesthetized using combinations of dexmedetomidine-based or ketamine-based anesthesia for induction and maintenance of anesthesia during the experimental portion of our study. Single stimulation of iSLN or vagus nerve, bilateral simultaneous single stimulation of iSLN or vagus nerve, and stimulus trains applied to afferent nerves were performed. Results: None of the seven pigs demonstrated evoked swallow events, both during inhalational anesthesia (1.0 MAC) or during post-washout intravenous anesthesia (dexmedetomidine, ketamine/fentanyl or ketamine alone). Conclusion: Our results support a high degree of organizational neurophysiologic complexity characterizing the swallow reflex and highlight the challenges and limitations of intraoperative study in survival models. Level of Evidence: NA Laryngoscope, 2018.