Patients
Between February 2009 and July 2013, 402 patients with clinical stage I (T1a, 1b, 2a N0M0) NSCLC underwent “VATS lobectomy” plus “non-grasping en bloc MLND” performed by one surgical team in our department. Informed consent was obtained from every patient before the operation. All patients underwent routine systemic function assessments, including blood tests and cardiopulmonary function text preoperatively. The preoperative staging consisted of routine computerized tomography (CT) scanning of the thorax and the upper abdomen, CT scanning or magnetic resonance imaging of the brain, bone scintigraphy, and bronchoscopy. The 18 F-fluorodeoxyglucosepositron emission tomography/CT (18 F-FDG-PET/CT) and/or mediastinoscopy were performed to those subjects with suspicious LN involvement shown on CT scans. Patients with documented positive LNs involvement were excluded from this study. Clinical and pathological data were prospectively collected and retrospectively reviewed for every patient. All LNs harvested were counted by the surgeon himself immediately after the operation and checked by pathologists postoperatively. Informed consent was obtained from each patient. This study was approved by the institutional review board of our hospital.
Surgical techniques
General anesthesia is administered to each patient through double-lumen endotracheal intubation. Each patient is placed in the appropriate lateral decubitus position. A 1.5 cm observation incision is made in the seventh intercostal space at the midaxillary line for the thoracoscope while two additional utility incisions are placed as follows: a 3 cm main utility incision is made at the anterior axillary line in the third intercostal space for the upper and middle lobes and in the fourth intercostal space for the lower lobes, and a 2 cm assistant utility incision is made in the ninth intercostal space (between the posterior axillary line and subscapular line). The surgeon stands in an anterior position to the patient. We prefer to perform lymphadenectomy after lobectomy, while some experts prefer to begin with lymphadenectomy. Lobectomy is performed following the “single-direction” strategy as in our previous description [16]. Dissection of LNs of stations 10, 11, and 12 is performed along with the lobectomy. The intralobar LNs (stations 13 and 14) were retrieved along with the resected lobe and anatomized by the surgeon himself. As recommended, we routinely dissect stations 2, 4, 7, 8, and 9 for right-side lobectomy and stations 4, 5, 6, 7, 8, and 9 for left-side lobectomy. Dissection of station 3 is performed only for selected patients if there are suspicious LNs found during operation.
It is better to perform video-assisted thoracoscopic MLND with fewer tools because of limited access ports. Keeping this point in mind, we have explored diversified and novel use of an ordinary metal endoscopic suction (MES) with side holes on the tip. Because of its suction capacity, MES can be used to “grasp” the target structure, and then to facilitate exposure by lifting or doing slight side compression of the target structure. This device can play simultaneous roles as peanut, grasper, and suction. Additional grasper or retractor and accompanied mutual interference among instruments can be saved. The MES can immediately suck away the smog or ooze to ensure a clear visual or operating field. In addition, an electrocoagulation hook (EcH), which plays roles as dissector and sealer, is used for precise excision and hemostasis. An ultrasonic scalpel (US), which produces reliable and durable ligation of small lymphatic or blood vessels, plays roles as blunt dissector, sealer, and clamper. A simple combination of the MES and the alternating use of the EcH or US are helpful in maintaining a clear operating field and are effective enough in dissection. During the operation, we avoided grasping the target LNs directly as possible. During a right-side procedure the MES is inserted through the assistant utility incision while the EcH or US was inserted through the main utility incision. However, during a left-side procedure the MES is inserted through the main utility incision while the EcH or US is inserted through the assistant utility incision. Instead of dissecting the target LNs only, we attempt to dissect the total fat pad located among the anatomic landmarks of each station. Adhering to the en bloc strategy, we carry out three-dimensional dissection following specific orders according to different anatomic features of each station. Modular dissection is carried out station by station. Detailed operative techniques are described as follows.
2 R and 4 R
With retraction of the remnant lung toward the right posterior costophrenic corner, the mediastinal pleura is opened by the EcH along the cephalad and caudal border of the azygos vein, and along the posterior border of the SVC to the caudal border of the innominate artery. With the help of MES, dissection of the block is initiated right beneath the arch of azygos vein by the US. The block is first dissected off the arch of azygos vein, and then hollowed out from the interspace surrounded by the arch of azygos, SVC, lower trachea, and ascending aorta (Figure 1A). Then the lower part of the block is free and will be flipped over the arch of azygos vein and lifted by the MES (Figure 1B). Next, the block is slightly pushed aside or lifted by the MES and dissected off the posterior border of the SVC, the lateral border of the ascending aorta, and the anterior border of the trachea sequentially from the cephalad border of the azygos vein to the caudal border of the innominate artery (Figure 1C). “Grasped” by the MES, the block will be dissected longitudinally and anterior to the vagus nerve en bloc (Figure 1D). Small venous or lymphatic vessels draining the mediastinal fat pad are ligated and cut by the US. At the apex, the right recurrent laryngeal nerve should be kept in mind and protected from thermal or mechanical injury with no necessity to expose it desperately.
7 R
The remnant lung is retracted toward the right anterior costophrenic corner to expose the posterior mediastinum and to increase the angle between the right and left main-stem bronchi. The mediastinal pleura is opened by the EcH posterior to the right main-stem bronchus and anterior to the esophagus, from the inferior ligament, up to the arch of azygos vein. The subcarinal block is first dissected off the esophagus until the left main-stem bronchus and the carina are identified (Figure 2A). During this process, the esophagus is pushed aside with the MES, and the block is detached from the esophagus mainly by EcH. In addition, a small bronchial artery arising from the aorta and entering into the right lung that is frequently present can be ligated with hemoclips and then cut by the US (Figure 2A). Retracted by the MES with certain tension, the block is then dissected off the pericardium and along the posterointernal border of the right main-stem bronchus to the level of carina by the US. Until here, the block has been dissociated three-dimensionally. At last, the block can be dissected off the carina and retrieved en bloc (Figure 2B and C), and when doing so, small feeding vessels entering into the subcarinal LNs from the region of the carina should be carefully dissected by the US to avoid bothersome bleeding. Meticulousness should be maintained to avoid injury to the membraneous portion of the right and left main-stem bronchi.
5 and 6
With retraction of the remnant lung toward the left posterior costophrenic corner, the mediastinal pleura is opened by the EcH posterior to the phrenic nerve and anterior to the vagus nerve, from the upper rim of the left main pulmonary artery to the aortic arch. The station 5 LN block is firstly dissected off the left main pulmonary artery by the EcH. Pushed aside or “grasped” by the MES, the block is then dissected by the US anterior to the vagus nerve and posterior to the phrenic nerve (Figure 3A). The station 6 LN block is commonly located between the phrenic nerve and the ascending aorta. We usually open the mediastinal pleura anterior to the phrenic nerve with the EcH (Figure 3B) and dissect the block with the US leaving the phrenic nerve hung free (Figure 3C and D). During the operation, the surgeon must keep in mind not to injure the phrenic and the vagus nerves.
4 L
With retraction of the remnant lung to the anterior costophrenic corner, the pleural area between the ligamentum arteriosum, left main pulmonary artery, vagus nerve, and left main-stem bronchus is opened by the EcH. The block is pressed downward by the MES, and is first dissociated from the inferior border of the aortic arch mainly by the EcH (Figure 4A). A bronchial artery that is frequently present here can be ligated (Figure 4A). Then, the block is dissected off the left main pulmonary artery and along the left main-stem bronchus to the trachea by the US (Figure 4B). Finally, the block is hollowed out from the interspace between the aortic arch, the left main pulmonary artery, and the left main-stem bronchus (Figure 4C). The left recurrent laryngeal nerve must be identified and meticulously protected, but with no need to anatomize it desperately.
7 L
Dissection of the subcarinal nodes from the left side is more difficult and time-consuming than that from the right side. With retraction of the remnant lung forward, the pleura area between the left main-stem bronchus, pericardium, and esophagus is opened. Similar to that performed on the right side, the subcarinal fat pad is first dissected off the esophagus by the EcH until the right main-stem bronchus and the carina are identified (Figure 5A). Then, the block is dissected off the pericardium and posterointernal border of the left main-stem bronchus by the US (Figure 5B). After that, the block is dissected off the right main-stem bronchus and the carina and retrieved en bloc by the US (Figure 5C and D). The small feeding vessels, which commonly enter into the LNs from the anterior border of the trachea at the level of the carina, must be identified, and clipped or ligated to avoid bleeding. The membranous portion of the left and right main-stem bronchi should not be injured.
3, 8, and 9
A great variation might exist in the number and consistency of station 3 (prevascular and retrotracheal LNs), station 8 (paraesophageal LNs), and station 9 (LNs embedded in pulmonary ligament). Nodes can be completely absent. We retrieve station 3 LNs only when there are obvious prevascular and/or retrotracheal lymphadenectasis. We retrieve station 8 LNs, if there would be any, when we perform dissection of station 7 LNs. Dissection of station 9 LNs is accomplished when we cut off the inferior pulmonary ligament.