Development of a new trans-oral endoscopic approach for mediastinal surgery based on 'natural orifice surgery': preclinical studies on surgical technique, feasibility, and safety.

OBJECTIVE In recent years, several surgical disciplines adopted endoscopic techniques. Presently, natural orifice approaches are under exploration to reduce surgical access trauma. We have developed a trans-oral endoscopic approach for endoscopic mediastinal surgery and have tested this new technique in preclinical studies for feasibility and safety. METHODS We conducted an experimental anatomical study in fresh-frozen cadavers. By a midline, sublingual incision, we placed an optical scissor through a 6.0-mm trocar in the pretracheal region and created a working space; two additional trocars were placed by bi-vestibular incisions in the oral cavity. We visualized and followed the trachea down to the main bronchi. Paratracheal and subcarinal lymph nodes were resected bilaterally; the specimen could be removed through the midline channel. In an additional animal study in pigs, we tested the feasibility and safety for this surgical approach. Anatomical dissection allowed an estimate of collateral damage. RESULTS In all cases, we could reach the target region endoscopically, and no conversion was necessary. Landmarks (the brachiocervical trunk, the azygos vein, and the pulmonary artery) were visualized easily and kept intact. A working space in the mediastinum could be established by the insufflation of air at 6-8mmHg. It was possible to harvest the specimen through the midline channel. Anatomical dissection of the cervical access route as well as of the mediastinal region showed no collateral damage. In the animal study, we encountered seroma of the surgical field due to the conditions of the animal model. The other outcomes with respect to pain and food intake were normal until the third postoperative day. No local infections occurred. Intraoperative gas exchange was normal and was not influenced by CO(2) insufflation with respect to blood gas analysis. CONCLUSION These preclinical studies showed that the mediastinum could be reached by a trans-oral endoscopic approach, based on natural orifice surgery. Complete compartment resection of the paratracheal and subcarinal lymph node stations was possible in a well-defined and clearly visible working space. This approach may enhance the extent of mediastinal resections in oncologic surgery.