Natural Orifice Transluminal Endoscopic surgery (NOTEs) is a unique emerging surgical concept that extends flexible endoscopy beyond the intestinal wall. At present, the application of NOTEs technology in the abdominal cavity has developed rapidly and has entered the stage of clinical operation. However, due to the existence of vital organs and the possibility of more severe complications in the mediastinal cavity, the application is mostly at the exploratory stage , and there are still technical limitations through natural orifices such as esophagus and trachea. The incision, closure and positioning are still urgent problems to be solved . The mediastinum has higher requirements for sterility. The surgery is performed through non-sterile holes such as the gastrointestinal tract, so NOTEs approach sterile environment does not meet the requirements to some extent.
NOTEs technology pursues no surface incision. Numerous animal experiments have been conducted to realize this concept, and various pathways are on trial [3, 5–7]. However, for the patients with esophageal cancer who are not feasible for ESD/EMR and need total esophagectomy and gastrointestinal reconstruction, it may be available in the future. Studies have shown that flexible endoscopy can provide good vision during mediastinal exploration and can perform basic operations such as pleural biopsy. In addition, due to its flexibility, you can go wherever you want [3, 8]. Besides, it has been reported that the flexible endoscopy can create a connective tissue tunnel to the distal esophagus to perform Heller Myotomy . The compact connective tissue tunnel has safe propulsion and stability for the endoscope . Combining previous literatures with NOTEs concept, in our operation, advanced endoscopic techniques are used to assist surgical operation and replace rigid mediastinoscopy and instruments. The subxiphoid incision can indwell a mediastinal drainage tube to prevent mediastinal emphysema and serious infection to a certain extent. More advanced technology to minimize surgical trauma and alleviate patient suffering.
Flexible endoscopy may have absolute advantages in the mediastinum, such as the ability to identify avascular embryonic tissue planes and conform to the tortuous mediastinal structure. Shorter operation time and undifferentiated intraoperative blood loss can prove the advantages. The lymphadenectomy under previous animal experiments requires the endoscopic ultrasound-guidance, positioning or the support of technologies such as nano-carbon [11–14]. In our clinical application, we have enough experience in MAE. A low level of positive pressure carbon dioxide insufflation could provide ample exposure space, which is not a cumbersome operation.
The flexible mediastinoscopy can reach anywhere close enough through the endoscopic magnification. Blunt and sharp separation complete the lymphadenectomy jointly. Instead of lymph node polymer, select a single lymph node dissect. Some reports state that it is a safe strategy to dissect the left recurrent laryngeal nerve lymph nodes (RLN LNs) during esophageal cancer surgery under the flexible laparoscope . Our results and experience also verify that it is safe and effective to perform this operation through articulator grasper and IT knife in the context of neuro-denseness. The transparent cap on the front can reduce the damage to the adjacent mediastinal structure theoretically and provide a more stable operating vision. In comparison, conventional mediastinoscopy requires some additional auxiliary rigid instruments to expose the surgical space. In the narrow space, it is not only necessary to overcome the triangular position of rigid instruments, but also to overcome the influence of breathing movement. For rigid instruments, it is difficult even impossible to access to the distant esophagus and mediastinum. It is hard to reach the level of inferior pulmonary vein.
Due to the LCS and trachea's nearly parallel angle and the poor visual field, it is not easy to dissociate the subcarinal lymph nodes. In contrast, since positioning the trachea is the easiest in the narrow endoscopic vision and the operational port is flexible, obviously the flexible mediastinoscopy is more suitable.
However, the risk of postoperative pleural effusion in the flexible mediastinoscopy group was higher than that in the conventional mediastinoscopy group. Our conjecture is that we were relatively unfamiliar with the esophageal outer boundary initially, which was caused by the injury of pleura, and it is proved by the fact that the latter 7 patients did not have such complications. Clear fluid drained from pleural canals, no bacterial infection found in hydrothorax culture, and no severe mediastinal infection found in postoperative CT, all of this proved that our aseptic operating environment was qualified.
So far, the indications and contraindications for the MAE are still controversial, and there is no comprehensive and recognized standard. Many comparative studies have demonstrated the feasibility of MAE, and in the course of long-term follow-up, the treatment effect is similar to transthoracic esophagectomy [2, 16, 17]. MAE avoids transthoracic operations, and it can be considered as a more friendly technique for patients with poor cardiac and pulmonary function, or a history of pleural disease . It doesn’t need to change position. Besides, the operation time is relatively shortened. Early studies reported numerous instruments and methods to improve MAE, but the standard technology has not yet established . Conventional mediastinoscopy has not been widely used due to the limited vision and operational inconveniences. Besides, it is just regarded as a palliative surgical treatment for the patients with significant tumor invasion or mediastinal lymph nodes involvement. We believe that the flexible mediastinoscopy could make MAE indications more extensive to some extent. As for the advanced tumors, we are making relevant attempts.
It is essential to be familiar with the esophageal anatomy and physiology in the application of flexible endoscopic techniques. The cardiothoracic surgeon's unfamiliarity with flexible endoscopes will undoubtedly slow the transition from research protocols to clinical applications in thoracic surgery. In our operation, the flexible mediastinoscopy is carried out with the joint efforts of particularly experienced endoscopists and under thoracic surgeons with rich MAE experience. We believe that both flexible and rigid mediastinoscopy can safely achieve the operation of the thoracic esophagus, while the flexible mediastinoscopy has better advantages due to its less aggressiveness, its stability in a narrow space, and its flexibility. It provides more possibilities for MAE. We proposed the concept of flexible mediastinoscopy. We believe that, with the development of more innovative endoscopic instruments, the flexible mediastinoscopy might have great application value.