(0821) Laryngeal Injury After Prone Positioning: A Cadaveric Evaluation of Endotracheal Tubes-Larynx Contact Pressures

Introduction: The advent of the novel coronavirus disease 2019 (COVID-19) has led to an increase in laryngotracheal stenosis (LTS) diagnoses. There is a 40% incidence of LTS in COVID-19 patients (6.3% classified as severe) and prolonged orotracheal intubation is known to be associated with increased rates of posterior glottic injury in this population. The effect of prone positioning on laryngeal contact pressure has not been studied. The aim of this project is to compare endotracheal tube (ETT) pressure on the posterior glottis in supine and prone Thiel-embalmed cadavers.

Methods: A custom pressure sensor device was developed using an Arduino microcontroller board (Turino, Italy) interfaced with a flexible thin film resistive pressure sensor. The sensor was affixed to 7.5 mm and 8 mm Shiley TaperGuard Evac endotracheal tubes (Covidien; Dublin, Ireland) in the posterior position. The apparatus was covered in Tegaderm (3M; Cottage Grove MN, USA) and a latex cover to prevent fluid intrusion onto the sensor. Two cadavers (male and female) were intubated such that the pressure sensor rested on the posterior glottic commissure. Glottic contact pressure measurements were made in the supine and prone positions in triplicate.

Results: The male cadaver’s mean posterior glottic pressure was 388g supine (range 200g-885g) and 662g prone (range 398g-892g) (p < 0.001). The female cadaver’s mean posterior glottic pressure was 586g supine (range 202g-1794g) and 1659g prone (range 944g-2183g) (p < 0.001).

Conclusions: In this Thiel-embalmed cadaveric study, prone positioning increased the pressure exerted onto the posterior glottis compared to supine positioning. The female cadaver, with a smaller glottic opening, experienced higher contact pressures overall compared to the male cadaver.