Development of Ultrasonically Activated Bending Scalpel for Endoscopic Surgery

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Ultrasonically activated scalpels are used clinically to provide hemostatic cutting in endoscopic surgery. To assist the physician during endoscopic surgery, we developed an ultrasonically activated bending scalpel constructed of super elasticity alloy ( SEA in short ). First, we performed the vibration analysis and its verification in bending state of ultrasonically activated scalpel. We found out that longitudinal vibration was transmitted even if probe was bent. The influence of transverse vibration is very small. There is no trouble destroying tissue contacts with the probe. Next, a SEA bending probe and its bending angle control system were manufactured as an experiment. From the experiment using chicken, we evaluated the validity of the bending scalpel. From this research, we found out that it is possible to bend the probe of ultrasonically activated scalpel by using Super Elasticity Alloy, and the activation of ultrasonically activated scalpel could be realized.Although, a lot of surgeons have used ultrasonic coagulating and cutting systems and shears ( LCS ) in performing endoscopic thryroidectomies and parathyroidectomics and parathyroidectomies, our experience showed that some patients had temporary paralysis of the recurrent laryngeal nerve ( RLN ) after these operations. We sometimes noticed that the heat of the blade of the LCS was raised just after use; therefore, we designed the RLN model and investigated the damage to the RLN attributable to by heat of LCS. We investigated the effects of the heat of the blade of LCS upon rats' femoral and sciatic nerves using temperature measurements, histological examinations and evoked electromyography. Our results suggest that we should not touch the RLN directly with the blade just after using it, and that it is possible to use LCS at a distance of 3mm from the RLN for less than 20 sec at level 3. In order to maintain these distances requires visualizing the RLN in the view of endoscope at the neck surgery.