In vitro model for testing novel implants for equine laryngoplasty

Abstract

Objective - To develop an in vitro laryngeal model to mimic airflow and pressures experienced by horses at maximal exercise with which to test laryngoplasty techniques. Study Design - Randomized complete block. Sample Population - Cadaveric equine larynges (n=10). Methods - Equine larynges were collected at necropsy and a bilateral prosthetic laryngoplasty suture was placed with #5 Fiberwire™ suture to achieve bilateral maximal arytenoid abduction. Each larynx was positioned in a flow chamber and subjected to static flow and dynamic flow cycling at 2 Hz. Tracheal pressure and flow, and pressure within the flow chamber were recorded at a sampling frequency of 500 Hz. Data obtained were compared with the published physiologic values for horses exercising at maximal exercise. Results - Under static flow conditions, the testing system produced inspiratory tracheal pressures (mean±SEM) of -33.0±0.98 mm Hg at a flow of 54.48±1.8 L/s. Pressure in the flow chamber was -8.1±2.2 mm Hg producing a translaryngeal impedance of 0.56±0.15 mm Hg/L/s. Under dynamic conditions, cycling flow and pressure were reproduced at a frequency of 2 Hz, the peak inspiratory (mean±SEM) pharyngeal and tracheal pressures across all larynges were -8.85±2.5 and -35.54±1.6 mm Hg, respectively. Peak inspiratory flow was 51.65±2.3 L/s and impedance was 0.57±0.06 mm Hg/L/s. Conclusions - The model produced inspiratory pressures similar to those in horses at maximal exercise when airflows experienced at exercise were used. Clinical Relevance - This model will allow testing of multiple novel techniques and may facilitate development of improved techniques for prosthetic laryngoplasty. © Copyright 2008 by The American College of Veterinary Surgeons.