Evaluation of the Laryngeal Adductor Reflex with a Mechatronic Micro-droplet Laryngoscope

• Applicants: Professor Dr.-Ing. Lüder Alexander Kahrs; Professor Dr. Martin Ptok
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics ; Otolaryngology, Phoniatrics and Audiology
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 314572885

• Final Report Year: 2022

Final Report Abstract

The laryngeal adductor reflex (LAR) is a vital mechanism of the human larynx, protecting the lower airways by vocal fold medialization. The LAR may be weakened in case of neurological impairment, increasing the risk of dangerous pneumonia due to accidental inhalations of foreign particles. Moreover, the neural control of the LAR has not yet been fully elucidated. To detect reflex pathologies and to facilitate further research regarding LAR characterization, a reproducible method for triggering and assessing this reflex is highly desirable. In the present project, a system of hardware and software components was developed to explore methods for the targeted, droplet-initiated LAR stimulation as well as for the automated analysis of simultaneously recorded, laryngoscopic high-speed frame sequences. Part of the developed system is an integrated droplet applicator module, which enables the formation of a stable LAR stimulation droplet with a known muzzle energy and a reproducible trajectory. To assist the clinical operator of the system, fluid system pressure regulation and control of the integrated solenoid valve have been automated, ensuring constant system parameters. Two different, custom-built laryngoscopes allow the visualization of the vocal folds and the surrounding tissue as well as the stereoscopic detection of the trajectory of a released droplet. This enables a prediction of the droplet impact site in the laryngoscopic image to guide the clinical user during the LAR evaluation procedure. After recording the LAR activity with a high-speed camera integrated in the stereolaryngoscopic system, the movement of the vocal folds after impact of the stimulation droplet can be tracked and LAR-related parameters can computationally be extracted from the frame sequence using algorithms developed in this project. Even though some challenges remain before a clinically approved MIT-LAR (Microdroplet Impulse Testing of the LAR) system can be introduced into the clinical routine, the obtained results represent a significant step forward with respect to the state of the art in the field of reproducible, objective, and safe screening methods of the laryngeal adduction reflex.

Publications

• (2017): Towards microprocessor-based control of droplet parameters for endoscopic laryngeal adductor reflex triggering, Current Directions in Biomedical Engineering 3(2): 239-243
  Fast JF, Muley A, Kühn D, Meisoll F, Ortmaier T, Jungheim M, Ptok M, Kahrs LA
  
• (2018): Risiko einer Lungenentzündung besser erkennen – 3D-High-Speed-Jet-Endoskop verbessert Kehlkopfdiagnostik, Technologie-Informationen 3|2018, Arbeitskreis der Technologietransferstellen niedersächsischer Hochschulen (Hrsg.)
  Fast JF, Kahrs LA, Ptok M
  
• (2018): Towards Fully Automated Determination of Laryngeal Adductor Reflex Latencies through High-Speed Laryngoscopy Image Processing, Bildverarbeitung für die Medizin 2018: 121-126
  Fast JF, Ptok M, Jungheim M, Szymanski R, Ortmaier T, Kahrs LA
  
• (2019): An actuated larynx phantom for pre-clinical evaluation of droplet-based reflex-stimulating laryngoscopes, Current Directions in Biomedical Engineering 5(1): 137-140
  Fast JF, He J, Jungheim M, Ortmaier T, Ptok M, Kahrs LA
  
• (2019): Aufbau eines bildleiterbasierten Stereo-Laryngoskops für das anatomiegerechte Routine-Screening der Latenz des laryngealen Adduktionsreflexes nach Auslösung durch Tropfenbeschuss, 36. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie (DGPP)
  Fast JF, Krauth M, Ortmaier T, Ptok M, Kahrs LA
  
• (2019): Endoscopic guidance system for stimulation of the laryngeal adductor reflex by droplet impact, Proc. SPIE 10951, Medical Imaging 2019: Image-Guided Procedures, Robotic Interventions, and Modeling, 109510M: 1-10
  Fast JF, Rüppel AK, Bärhold C, Jungheim M, Ortmaier T, Ptok M, Kahrs LA
  
• (2020): Droplet applicator module for reproducible and controlled endoscopic laryngeal adductor reflex stimulation, Biomicrofluidics 14 044112:1-16
  Fast JF, Westermann KA, Laves MH, Jungheim M, Ptok M, Ortmaier T, Kahrs LA
  
• (2020): Euclidean distances of laryngopharyngeal structures obtained from CT data for preclinical development of laryngoscopic devices, Surgical and Radiologic Anatomy 42(6): 695-700
  Diers D/Fast JF, Götz F, Kahrs LA, Miller S, Jungheim M, Ptok M
  
• (2021): Stereo Laryngoscopic Impact Site Prediction for Droplet-Based Stimulation of the Laryngeal Adductor Reflex, IEEE Access 9: 112177-112192
  Fast JF, Dava HR, Rüppel AK, Kundrat D, Krauth M, Laves MH, Spindeldreier S, Kahrs LA, Ptok M
  
• EP3536226 – Medizinische Vorrichtung, Verfahren zur Prädiktion eines Auftrefforts und Computerprogramm (europäisches Patent, erteilt am 17.02.2021)
  Fast JF, Kundrat D, Ptok M, Kahrs LA
  
• (2022): Computational Analysis of the Droplet-Stimulated Laryngeal Adductor Reflex in High-Speed Sequences, The Laryngoscope (Early View):1-8
  Fast JF, Oltmann A, Spindeldreier S, Ptok M