Robot-assisted transnasal laryngoplasty in cadaveric models: Quantifying forces and identifying challenges.

Objectives/hypothesis: We expanded our prior work with transnasal robotic surgery (TNRS) in this study with the following aims: 1) use a cadaveric model to evaluate the feasibility of laryngoplasty with TNRS, 2) measure robot insertion times and forces, and 3) identify operational challenges to further guide the development of a flexible robotic system.

Study Design: Cadaveric study.

Methods: A 5-mm robot was guided to the larynx via a transnasal approach. Insertion times and forces using TNRS and a 4-mm flexible fiberoptic laryngoscope (FFL) were measured. Target sites on the true vocal cords were marked, and the TNRS was telemanipulated to perform injection laryngoplasty.

Results: Insertion times averaged 5.05 seconds (range, 3.8-10.4 seconds) for the TNRS and 7.97 seconds (range, 6.2-11.6 seconds) for the FFL. Insertion forces averaged 2.06 newtons (range, 1.56-5.55 newtons) for the TNRS and 0.43 newtons (range, 0.157-1.138 newtons) for the FFL. The unpaired t test between times and forces revealed P values of .0024 and .0000658, respectively. Seven target injection sites on three vocal cords in two cadaveric larynxes were successfully injected. In two out of nine sites marked, we were unable to access the vocal cord due tongue base collapse that obscured the posterior airway.

Conclusions: TNRS is able to effectively access the larynx, although in a supine model may be limited by tongue base collapse. Forces with TNRS were significantly higher than with the FFL, albeit within the same scale. Despite increased forces, there was no evidence of tissue trauma using TNRS.

Level Of Evidence: NA Laryngoscope, 125:1166-1168, 2015.