Study On Safety Application Of Energy Equipment Of LigaSure In Thyroid Surgery

Objective: To study the safety distance and safety interval of the LigaSure Small Jaw used near the recurrent laryngeal nerve (RLN) in thyroidectomy, we simulated application of ligasure near the RLN on porcines protected by continuous intraoperative neuromonitoring(CIONM).Methods:1. Experimental animal grouping:36 porciines were randomly divided into the distance study group and the interval study group, each group of 18 porcines. The distance study group was randomly divided into group 1 (3 mm from RLN)、group 2 (2 mm from RLN) and group 3(1 mm from RLN) according to the distance between LigaSure and RLN, each group of 6 porcines. The interval study group was randomly divided into group 1(cooling 3s)、group 2 (cooling 2s) and group 3 (cooling 1s) according to different cooling times at room temperature,each group of 6 porcines.2. Experimental model preparation:1) Anesthesia and application of CIONMThe animals were intravenously anesthetized with thiopental (15 mg / kg) and a nerve integrity monitor endotracheal tube was inserted under the guidance of Laryngoscopy. Then ECG and Oxygen Monitoring were connected and anesthesia was maintained with sevoflurance (1-2%).Vagal nerve(VN)exposure, APS electrode position and RLN exposure were followed the CIONM application standardization steps to monitor RLN function.2) Distance study18 left RLNs (right side control) were selected and the application site was selected between the 2nd and 3rd tracheal cartilages. According to different groups,the LigaSure Small Jaw was activated 4s at 3mm、2mm and 1mm from the RLN respectively. CIONM was used to monitor RLN function. Amplitude and latency were compared before and after the excitation. To observe recovery of RLN function, we monitored 30min after excitation and recorded real-time amplitude and latency of 15min and 30min after excitation.3) Interval study18 left RLNs (right side control) were selected and firstly LigaSure Small Jaw was activated on the sternocleidomastoid muscle for 5s. Open the head of LigaSure Small Jaw and contacted with the RLN between the 2nd and 3rd tracheal cartilages level directly after 3s、2s or 1s cooling times at room temperature. The EMG contrast before and after injury and observation of RLN function were same as distance study.3. Pathological sectionsThe experimental side of RLN and the right side of the normal RLN were made pathological sections to observe of histological changes.Results:1. Distance studyThere was no significant EMG change after excitation in group 1 and amplitude and latency fluctuated within the normal range. And also had no statistically significance. Group 2 and group 3 showed varying degrees of amplitude redution and latency extension. In Group 2, amplitude reduction were less than 50% and latency extension were less than 10%. The monitor had no alarm and the change had no statistically significant. The EMG can be restored to the normal range before injury in 30min. Group 3 appeared dangerous EMG and the monitor alarmed. After the injury the amplitude and latency were recovered, but it did not reach the threshold level of warning in 30min. The amplitude and latency before and after injury of had statistically significant in Group 3. Group 1,group 2 and control group showed normal nerve structure under microscopic and Group 3 showed nerve edema.2. Interval studyIn Group 1,amplitude reduction were less than 50% and latency extension were less than 10% after injury. The monitor had no alarm and the change had no statistically significant. The EMG can be restored to the normal range before injury in 30min. EMG of group 2 and group 3 changed rapidly after injury and the alarm appeared. The amplitude and latency before and after injury of had statistically significant. In Group 2, the amplitude and latency were recovered after the injury, but it did not reach the threshold level of warning in 30min. Group 3 appeared LOS and could not be recovered after injury. Group 1 and control group showed normal nerve structure under microscopic. Group 2 showed nerve edema and group 3 showed nuclei fragmentation and necrosis.Conclusion: Based on the CIONM evaluation of the function of RLN, the safe distance for LigaSure Small Jaw activation was further 2mm near the RLN and after a single excitation, time interval should be no less than 3s before next excitation. The use of LigaSure Small Jaw should be standardized to avoid the occurrence of energy thermal injury of RLN. CIONM can evaluate real-time function changes of RLN sensitively and identify injury in its earliest phases. It can also remind the surgeon to predict and control the injury. CIONM is of great significance to neuroprotection and worthy of promotion...