An Ophthalmic Anesthesia Training System Using Integrated Capacitive and Hall Effect Sensors

Regional anesthesia delivery for ocular surgery involves insertion of a syringe needle into the orbital space at the proper position and orientation such that ocular structures remain undamaged while avoiding adverse systemic reactions. Additionally, anesthetic fluid must be injected at an appropriate rate to achieve painless and rapid akinesia. Training on human subjects is risky and animal cadavers do not emulate human ocular anatomy. Thus, a training system, which closely replicates human ocular anatomical structure and provides real-time qualitative feedback on the effectiveness and safety of the anesthetic procedure would significantly mitigate risks associated with real life procedures. This paper presents a rapid prototyped, anatomically precise training manikin that detects the proximity and touch of syringe needle to the extraocular muscles and alarms the trainee to avoid injury. The proximity of the needle to the muscle structure is detected using capacitive sensors integrated in the manikin. A Hall-effect sensor-based measurement scheme for detection of rate of injection from a syringe has been developed. The specially designed syringe piston provides illusion of fluid flow inside the manikin for the trainee while reducing anesthesia wastage. A virtual instrument developed measures the output from capacitive sensing electrodes and Hall-effect sensor and displays it to the trainee through a graphical user interface. The proposed capacitive touch and proximity detection schemes have been validated by tests performed on the prototype system. The rate of injection was measured in real time on a prototype syringe, demonstrating the practical use of the system for medical training purposes.