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.