Effects of a novel, 3D printed bilateral arytenoid abductor on canine laryngeal airway resistance ex vivo

Abstract

Background: Laryngeal paralysis is a disease process most commonly seen in older, large breed dogs. When both arytenoid cartilages are affected dogs can develop life-threatening respiratory compromise, therefore surgical intervention is recommended. While there are multiple surgical procedures that have been described to treat laryngeal paralysis, there remains a considerable risk for postoperative complications, most commonly aspiration pneumonia. The objective of this ex vivo experimental study was to evaluate the effects of a novel, 3D printed bilateral arytenoid abductor on laryngeal airway resistance in canine cadaver larynges. Laryngeal airway resistance was calculated for each specimen before (control) and after placement of a 3D printed, bilateral arytenoid abductor. The airway resistance was measured at an airflow of 10 L/min with the epiglottis closed and at airflows ranging from 15 L/min to 60 L/min with the epiglottis open. The effects of the bilateral arytenoid abductor on laryngeal airway resistance were evaluated statistically.

Results: With the epiglottis open, median laryngeal airway resistance in all larynges with a bilateral arytenoid abductor were significantly decreased at airflows of 15 L/min (0.0cmH2O/L/sec), 30 L/min (0.2cmH2O/L/sec), and 45 L/min (0.2cmH2O/L/sec) compared to the controls 15 L/min (0.4cmH2O/L/sec; P = 0.04), 30 L/min (0.9cmH2O/L/sec; P = 0.04), and 45 L/min (1.2cmH2O/L/sec; P = 0.04). When the epiglottis was closed, there was no significant difference in laryngeal resistance between the control (18.8cmH₂O/L/sec) and the abducted larynges (18.1cmH₂O/L/sec; P = 0.83).

Conclusions: Placement of a bilateral arytenoid abductor reduced laryngeal resistance in canine cadaver larynges compared to the controls when the epiglottis was open. With the epiglottis closed, there was no loss of laryngeal resistance while the device abducted the arytenoid cartilages. The results of this ex vivo study is encouraging for consideration of further evaluation of the bilateral arytenoid abductor to determine an appropriate material and tolerance of this device in vivo.

Keywords: Arytenoid abductor; Laryngeal airway resistance; Laryngeal paralysis.

Fig. 1

Image of a cadaver larynx mounted in the testing chamber for measurement of airway pressure. The inflow at the end of the chamber is connected to a high-flow air circuit. The outflow end has an airtight seal around the tracheal rings but the lumen of the trachea is continuous with the environment. The two ends of the stay suture for epiglottic manipulation have been passed down the trachea and attached to mosquito hemostats

Fig. 2

Computer generated renderings of the bilateral arytenoid abductor using Autodesk Meshmixer (A). Dorsal and ventral views of 3D-printed arytenoid abductor (B). Arytenoid abductor secured in situ (C), with an endotracheal tube in place (D) and with the epiglottis closed (E)