In Vitro Model for Testing Novel Implants for Equine Laryngoplasty

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.