Video-assisted thoracoscopic surgery (VATS) is generally

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1 Early Experience With Robot-Assisted Surgery for Mediastinal Masses Johannes Bodner, MD, Heinz Wykypiel, MD, Andreas Greiner, MD, Werner Kirchmayr, MD, Martin C. Freund, MD, Raimund Margreiter, MD, and Thomas Schmid, MD Departments of General and Transplant Surgery, Vascular Surgery, and Radiology, Innsbruck University Hospital, Innsbruck, Austria Background. We report the experience of a single institution with the minimally invasive resection of mediastinal masses using the da Vinci robotic surgical system. Methods. From August 2001 to June 2003, 14 patients (5 men and 9 women aged from 21 to 77 years) with mediastinal masses were operated on minimally invasively with the da Vinci robotic system. This consisted of 9 thymectomies (6 thymomas, 2 nonatrophic thymic glands, 1 thymic cyst), 3 resections of paravertebral neurinomas, 1 ectopic mediastinal parathyroidectomy, and 1 resection of a lymphangioma. Results. Complete, extended thymectomy was accomplished in all 9 cases, proven by examination of the thymic bed and resected specimen. In 1 patient with an hourglass-shaped neurinoma, conversion to an open procedure was necessary because the excessive size of the tumor limited vision. The median overall operation time was 166 minutes (range, 61 to 182) including 110 minutes (range, 46 to 142) for the robotic act. There were no intraoperative complications or surgical mortality. Conclusions. These preliminary results of our series suggest that application of the da Vinci robotic surgical system for resection of selected mediastinal masses is technically feasible and safe. It provides an alternative to open approaches and conventional thoracoscopy. Nevertheless, this new technique requires further investigation in larger series and longer follow-up. (Ann Thorac Surg 2004;78:259 66) 2004 by The Society of Thoracic Surgeons Video-assisted thoracoscopic surgery (VATS) is generally accepted for diagnostic and therapeutic procedures in patients with a mediastinal mass [1 7]. It allows excellent exposure of the operating field and facilitates precise dissection, thus providing the advantage of minimal invasive surgery with little operative trauma [1, 3, 7]. More recently, the introduction of robotic surgical systems opened new possibilities in various surgical fields. The da Vinci robotic system (Surgical Intuitive, Mountain View, CA) provides excellent threedimensional vision as well as motility of endosurgical instruments. Selected procedures in cardiac and general surgery using this system have been reported [8 11]. At present, the use of robotic surgery in urology and gynecology is under evaluation. The few reports on the use of robotic systems in thoracic surgery and the fact that only some single-case reports on robotic mediastinal mass resection have been published prompted us to analyze our experience with 14 cases of resection of mediastinal masses with the da Vinci system [12 16]. Accepted for publication Feb 3, Address reprint requests to Dr Schmid, Department of General and Transplant Surgery, Innsbruck University Hospital, Anichstrasse 35, A-6020 Innsbruck, Austria; thomas.schmid@uklibk.ac.at. Patients and Methods From August 2001 to June 2003, a total of 27 patients were referred to our department for surgery of a mediastinal mass; of these 27, 14 met the criteria for a thoracoscopic procedure. Robot-assisted surgery was offered to them and approved by our local ethics committee. Informed consent was obtained from all patients. The remaining 13 patients were not considered for robot-assisted surgery, because they did not meet the criteria for minimal invasive surgery (n 11) or no surgeon with experience in this type of surgery was available (n 2). They underwent open or conventional VATS surgery. The median age of the 14 patients in the study group (5 men, 9 women) was 61 years (range, 21 to 77). The lesion was located in the upper anterior mediastinum in 10 patients, in the middle anterior mediastinum in 1 patient and in the posterior mediastinum in 3 patients. Indications for thymectomy (n 9) were an asymptomatic thymoma in 4 patients; myasthenia gravis in 3, 2 of whom had a noninvasive thymoma at computed tomography (CT) scan; and a thymic cyst in 1 patient. One other patient had symptoms of Cushing s syndrome with the thymus considered to secret the adrenocorticotrophic hormone. In 1 patient, indication for surgery consisted of an unclear nonthymic anterior mediastinal mass. Three patients were operated on for a tumor presumably of neurogenic origin in the paravertebral gutter. The remaining patient was operated on for an ectopic parathy by The Society of Thoracic Surgeons /04/$30.00 Published by Elsevier Inc doi: /j.athoracsur

2 260 BODNER ET AL Ann Thorac Surg ROBOTIC SURGERY FOR MEDIASTINAL MASSES 2004;78: Table 1. Indication for Resection, Location, and Size of Each Lesion and Number of Trocars Patient No. Sex Age (years) Indication Location Side Size (mm) Trocars Auxiliary Trocars 1 M 72 Thymoma Upper anterior Right M 72 Thymic cyst Upper anterior Right M 65 Thymoma Upper anterior Right F 77 Thymoma Upper anterior Right M 67 Myasthenia gravis thymoma Upper anterior Right F 28 Ectopic Cushing Upper anterior Right F 25 Myasthenia gravis thymoma Upper anterior Right/left F 21 Myasthenia gravis Upper anterior Right F 71 Thymoma Upper anterior Right F 61 Mediastinal mass Upper anterior Left M 56 Paravertebral tumor Costovertebral sulcus Left F 40 Paravertebral tumor Costovertebral sulcus Right F 73 Paravertebral tumor Costovertebral sulcus Right F 58 Ectopic parathyroid Aortopulmonary window Left F female; M male. roid gland in the aortopulmonary window. More patient characteristics and details are summarized in Table 1. Robotic System The da Vinci robotic system consists of a master console, where the surgeon handles telemanipulators and optical controls using three-dimensional vision and the surgical arm cart, a manipulator unit with two instrument arms, and a central arm to guide the two-channel endoscope. Specific robotic surgical instruments are introduced through special ports and attached to the arms of the robot. The surgeon s movements on the handles are transmitted to the tips of the robotic instruments. The main technological advantages of this system are realistic three-dimensional imaging, motion-scaling, and tremor filtration. Thus, it facilitates more precise and accurate endoscopic surgery as compared with VATS. Robotic procedures are usually performed by two surgeons, the surgeon at the console and the tableside surgeon, who places the trocars and connects them with the robotic arms, changes the robotic instruments, and manipulates additional endoscopic instruments through the auxiliary ports, if needed. The robotic trocars are 10 mm for the binocular robotic camera and 8 mm for the instruments. By elevating the robotic camera arm, the thoracic wall can be pulled up, thus enlarging the visceral compartment. This maneuver is called the thoraco-lift. As in conventional thoracoscopy, a 30-degree endoscope is used. Surgical Technique Patients were intubated with a double-lumen tube for selective single-lung ventilation. For thymectomy, all but 1 patient were placed in an incomplete (side up at a 30-degree angle right or left) lateral decubitus position. The arm of the elevated side was positioned at the patient s side as far back as possible to gain enough space for the robotic arms. At our institution thoracoscopic thymectomy is usually performed from the right side for well-known reasons [6]. Only 1 patient was operated on from the left side, as CT scan showed a thymic cyst predominantly located on the left side. In 1 very petite female, a bilateral access was chosen and the patient placed in a dorsal position. Patients with a tumor in the posterior mediastinum were placed in an extreme lateral decubitus position. Standard right lateral decubitus position was applied in the patient with an ectopic parathyroid adenoma and in the patient with a mediastinal lymphangioma. At the end of the procedure a chest tube was placed in the pleural cavities. Thymectomy The port for the robotic endoscope was positioned in the sixth intercostal space in the middle axillary line. A more ventral position would facilitate controlateral preparation but hamper ipsilateral dissection. The camera was inserted and the two robotic instrument ports were placed under vision in the third and sixth intercostal spaces, one hand s breadth left and right of the camera trocar, respectively. These two ports were positioned at 70 degrees to 90 degrees to prevent extracorporal collision of the robotic arms. An auxiliary port was inserted dorsal to and between the camera and the left instrument trocar. The position of the three robotic ports and the auxiliary port are depicted in Figure 1. An extended thymectomy with en bloc resection of the anterior mediastinal fat tissue including the thymus, as described by Masaoka [17], was performed. The adipose tissue around the upper poles of the thymus around both brachiocephalic veins and on the pericardium was dissected meticulously. Dissection limits were the diaphragm caudally, the thyroid gland cranially, and the phrenic nerves laterally.

3 Ann Thorac Surg BODNER ET AL 2004;78: ROBOTIC SURGERY FOR MEDIASTINAL MASSES 261 Fig 1. Schematic illustration of a thymectomy. (S surgeon; TS table surgeon; AN anesthetist; SN surgical nurse; IN instruments; TV conventional monitor.) The cart was moved toward the patient s ventral side and the robotic arms connected to the ports. For dissection, the Cadiere forceps (Surgical Intuitive, Mountain View, CA) was attached to the left arm, which was mainly used for grasping tissue. Dissection was performed with a robotic cautery hook on the right arm starting medial to the right phrenic nerve from cranial to caudal. En-bloc extirpation of fat tissue in the lower anterior mediastinum may be hindered by collision of the left robotic arm with the patient s shoulder. In this situation, a curved thoracoscopic grasper is inserted through the auxiliary port to achieve better exposure. Dissection was then continued to the substernal region and the controlateral pleural cavity was opened. The thymus was dissected free from the pericardium and preparation proceeded as far as the thymic veins. This was followed by dissection of the right and left upper horns and transection of the thymic veins. Larger vessels were clipped, smaller ones controlled by electrocautery. The da Vinci system enables the surgeon to also dissect the left thymic lobe accurately from a right-sided access in most patients. As previously mentioned, the dissection limit on the left side is the phrenic nerve. The specimen was removed in an Endobag (US Surgical, Norwalk, CT) inserted through the auxiliary port. In the patient with an obvious benign nonthymic lesion in the anterior mediastinum set-up and positioning of trocars were identical to those for the thymectomy procedure described above. Extirpation of Posterior Mediastinal Tumors Extirpation of posterior mediastinal tumors (Fig 2) was performed in 3 patients (2 lesions in the right and 1 in the left paravertebral gutter). The camera port was positioned in the anterior axillary line and the intercostal space was selected according to the location of the tumor. The ports for the two working arms were placed symmetrically one hand s breadth right and left of the camera trocar. The cart was then approached dorsocranially. An auxiliary port was not placed there unless it was needed. For dissection, the Cadiere forceps was again held in the left and the cautery hook in the right hand. The tumor was excised in toto with the covering parietal pleura. Extirpation of Tumor in Aortopulmonary Window The positions of the three robotic and the two auxiliary ports are shown in Figure 3. The camera port was inserted in the sixth intercostal space in the anterior axillary line and the two instrument ports were placed in the fourth intercostal space one hand s breadth right and left. A flexible retractor (US Surgical, Norwalk, CT) was inserted in the medioclavicular line of the sixth intercostal space through the first auxiliary port to keep the lung down. Suction was provided through a second auxiliary port, positioned in the posterior axillary line of the sixth intercostal space. Dissection was started by incising the parietal pleura covering the aortopulmonary window. Care must be taken not to injure the left vagal and recurrent laryngeal nerves. The tumor between the aortic arch, the trunk of the pulmonary artery, and the trachea was carefully excised by blunt dissection using the cautery hook. The vascular pedicle was controlled with metal clips. Results All procedures were performed by the same surgeon. Of 14 procedures, 13 (93%) were carried out with the da Vinci robotic system. In 1 patient with a large hourglasslike neurogenic tumor in the costovertebral gutter, conversion to a standard thoracotomy was necessary. The time for setting up the robot, the time for the surgeon working at the console (console time) and the overall operating time (first skin incision to skin closure) for each patient are given in Table 2. The median overall

4 262 BODNER ET AL Ann Thorac Surg ROBOTIC SURGERY FOR MEDIASTINAL MASSES 2004;78: Fig 2. Schematic illustration of a resection of a posterior paravertebral mediastinal tumor. The tumor is indicated by the arrow in the CT scan. (CT computed tomography; S surgeon; TS table surgeon; AN anesthetist; SN surgical nurse; IN instruments; TV conventional monitor.) operation time was 166 minutes (range, 61 to 182) including 110 minutes (range, 46 to 142) for the robotic act. There was no relevant intraoperative blood loss in any of the patients and no major surgical complications occurred. The robotic system itself did not show any technical failure. Chest tubes were removed on postoperative day 2 [2 6]. There were no postoperative complications after thymectomy or extirpation of a posterior mediastinal mass, whereas the patient in whom a tumor was removed from the aortopulmonary window suffered from transient postoperative hoarseness due to an incomplete palsy of the left laryngeal recurrent nerve. Eight months after surgery the patient has recovered completely. Histology Pathology revealed 6 thymomas (5 Masaoka stage I, 1 Masaoka stage II), 1 atrophic thymic gland, 1 large active thymic gland, and 1 thymic cyst. The nonthymic-anterior mass was histologically classified as lymphangioma. The 3 tumors extirpated from the costovertebral gutter were histologically of neurogenic origin and benign. The tumor in the aortopulmonary window was confirmed to be a parathyroid adenoma. Histology confirmed in all 14 patients that the resection margins were free of tumor (R0). After a follow-up of 16 months (range, 1 to 20), there is no clinical or radiologic sign of tumor recurrence in any of the patients including the 1 with invasive (Masaoka stage II) thymoma who refused adjuvant therapy. Comment Conventional VATS has become a widely accepted alternative for various thoracic procedures and the standard approach for mediastinal thymic as well as nonthymic benign lesions. However, most surgeons still hesitate to perform VATS for the resection of malignant tumors [3, 18 20]. The reason for this may be the limitation of conventional thoracoscopy with regard to accuracy and safety [21, 22]. The introduction of robotic surgical systems has added a new dimension to minimally invasive surgery. Hand movements in the grips of the console are naturally and intuitively transmitted to the robot s instruments. Ergonomics for the surgeon are much better than in conventional laparoscopic surgery and allow for even highprecision microsutures. Movement of the instruments allows seven degrees of freedom and is therefore superior to a surgeon s hand in open surgery. Anyone who works with a robot for the first time is amazed at the ability to require dexterity and accuracy with a very short learning curve [23]. After 2 years of experience with the da Vinci robotic surgical system and more than 100 general and thoracic surgical procedures, we still marvel at the precise movements of the instruments, the quality of the threedimensional camera image, and the stable operation field. The fact that the camera is robotically controlled provides an entirely stable camera image, and the need to clean the lens is less frequent. That has been shown to improve the motion coordination and the dexterity of the surgeon [24, 25]. These features pose an extraordinary advantage for operations in small and remote areas. Thus, resection of mediastinal lesions appears to be an ideal indication for the robot. So far, only 3 case reports on robotic surgery for benign thymic lesions have been published [13, 16, 26]. Our report is the first on a small series of thymectomies performed with the da Vinci robotic system. We demonstrate in 9 patients that thoracoscopic thymectomy with

5 Ann Thorac Surg BODNER ET AL 2004;78: ROBOTIC SURGERY FOR MEDIASTINAL MASSES 263 Fig 3. Schematic illustration of extirpation of a tumor in the aortopulmonary window. The tumor is indicated by the arrow in the CT scan. (CT computed tomography; S surgeon; TS table surgeon; AN anesthetist; SN surgical nurse; IN instruments; TV conventional monitor.) the da Vinci robotic system is routinely feasible. In all our 9 patients, an extended resection was sought due to myasthenia or potential malignancy because the final staging can be determined only on full specimen histology. The completeness of the procedure was proven by backtable investigation of the specimens and intraoperative evaluation of the resection margins. A striking example of the robot s benefit in tiny and remote areas is the dissection of the superior horns during extended thymectomy. That is sometimes cumbersome to achieve by means of conventional thoracoscopy but is quite easily performed with the robot. The VATS thymectomy has been performed more recently also in patients with thymoma [3, 27 30] but has not gained general acceptance for that indication, as long-term results are still lacking. We are very enthusiastic with our results with thymomas using the new robotic technology. Regardless of the tumor size and the nature of its surrounding capsule we sought complete thymectomy with en bloc removal of all mediastinal fat around the tumor in all cases, in contrast to enucleation of an encapsulated thymoma. Precise instrument movements as well as the active thoraco-lift and the superior three-dimensional vision enabled this type of surgery. The relative simplicity of the first thymectomies, resulting in complete and intact specimens, motivated us toward a robotic approach even in a case with a5cm tumor. Care was taken not to touch the tumor itself during any phase of the operation, and histology confirmed its intactness with free resection margins postop- Table 2. Set-Up, Console, and Overall Operating Time for Each Procedure Patient No. Procedure Set-Up Time (minutes) Console Time (minutes) Overall Time (minutes) 1 Thymectomy Thymectomy Thymectomy Thymectomy Thymectomy Thymectomy Thymectomy Thymectomy Thymectomy Resection of lymphangioma Resection of neurinoma Resection of neurinoma Resection of neurinoma (conversion) Parathyroidectomy

6 264 BODNER ET AL Ann Thorac Surg ROBOTIC SURGERY FOR MEDIASTINAL MASSES 2004;78: eratively. However, such exceptional cases need to be followed up thoroughly. The capacity of the robot allows for extended thymectomies even from a single-sided approach, which is critical for the conventional thoracoscopic procedure. Only in a small female patient was a bilateral approach chosen for anatomical reasons. In robotic surgery, the ideal positioning of the patient is crucial, because any change requires disconnection of the system, which is a time-consuming process. We evaluated various positions such as the classic lateral decubitus position, several lateral positions, and a strictly supine position. An incomplete left lateral position turned out to be most practicable. Care has to be taken to keep the right shoulder back in order to prevent interference with the left robotic arm, especially when beginning dissection along the right phrenic nerve. Whereas thymectomy is a complex minimally invasive procedure, the resection of masses in the posterior mediastinum is relatively simple and straightforward as long as the tumor does not involve nerve roots. The limitation on conventional VATS or the robotic approach, however, is the size of the tumor. One of these three interventions had to be converted to an open procedure. In this patient, the tumor size was 17 8 cm and a minimally invasive approach contraindicated; this tumor could not be grasped with any thoracoscopic instrument. In the other 2 patients, the robotic resection was performed without any problems. Total operating and console times were the shortest of all procedures. Based on this experience, we have restricted the tumor size for future minimally invasive approaches to a diameter of less than 10 cm. Another tumor was an ectopic mediastinal parathyroid in the aortopulmonary window. Although this entity is rare, its location makes it another domain for the robot. In this case, superb three-dimensional vision made it easy for the surgeon at the console to identify the tumor, whereas at the same time the surgeon at the table side, looking at a conventional monitor, found it difficult to recognize the lesion. From conventional open and thoracoscopic surgery, it is well known that ectopic parathyroids can often be identified only with the help of radionuclide guidance. We found dissection in the narrow aortopulmonary window to be accurate and safe, and we believe that the procedure would not have been feasible by means of conventional thoracoscopy. The transient lesion of the left recurrent nerve which occured in this procedure was due to dissection of the nerve from the tumor s capsule and was not based on limitations of the robotic system. One of the disadvantages of robotic surgery is its current lack of tactile feedback. At present, the operating surgeon cannot identify the consistency of the tissue he or she is handling. However, only about 10% of our sensory system is tactile and 70% to 80% derives from visual input [31 33]. Thus, a lack of haptic feedback is compensated by the superior image of the threedimensional camera. The introduction of certain haptic modalities to the robot will make working with it resemble open surgery even more. Another major obstacle for broader application of robotic surgery is, of course, its cost. The situation, however, is similar to that of CT scans or magnetic resonance tomographs in their early days, when they were affordable for bigger hospitals only. Competition between producers drastically brought down costs, and thus these devices are even in use today in smaller private institutions. For the present time, the robots outfit is very basic, as in the early days of laparoscopy. Special devices such as ultrasound dissectors and variously shaped clamps will certainly be developed, as will an accessory robotic arm that is able to position retractors, provide suction and irrigation. With these adaptations, we propose that working with the robot will be even easier and faster in the future. In our study, various complex surgical maneuvers were performed in the mediastinum without problem. Intraoperative and postoperative complications such as blood loss were comparable with those of conventional thoracoscopic interventions. The left laryngeal nerve palsy after parathyroidectomy, which eventually showed completele recovery, was an independent complication. We conclude that robotic surgery combines the advantges of conventional VATS with the accuracy and safety of an open procedure. However, the role of robotic systems in thoracic and general surgery has not yet been clearly defined. Wider application and the evaluation of long-term results will help to define appropriate indications. The authors thank Emeritus Prof Ernst Bodner, MD, for his vision and endeavors that enabled the acquisition of the da Vinci robot for the Department of Surgery, Innsbruck University Hospital. References 1. Demmy TL, Krasna MJ, Detterbeck FC, et al. Multicenter VATS experience with mediastinal tumors. Ann Thorac Surg 1998;66: Riquet M, Mouroux J, Pons F, et al. Videothoracoscopic excision of thoracic neurogenic tumors. Ann Thorac Surg 1995;60: Roviaro G, Rebuffat C, Varoli F, Vergani C, Maciocco M, Scalambra SM. Videothoracoscopic excision of mediastinal masses: indications and technique. Ann Thorac Surg 1994; 58: Kido T, Hazama K, Inoue Y, Tanaka Y, Takao T. Resection of anterior mediastinal masses through an infrasternal approach. Ann Thorac Surg 1999;67: Roberts JR, Blum MG, Arildsen R, et al. 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Ann Thorac Surg 1993; 55: Kaiser LR. Thymoma. The use of minimally invasive resection techniques. Chest Surg Clin North Am 1994;4: Bholat OS, Haluck RS, Kutz RH, Gorman PJ, Krummel TM. Defining the role of haptic feedback in minimally invasive surgery. Stud Health Technol Inform 1999;62: Bholat OS, Haluck RS, Murray WB, Gorman PJ, Krummel TM. Tactile feedback is present during minimally invasive surgery. J Am Coll Surg 1999;189: Meier AH, Rawn CL, Krummel TM. Virtual reality: surgical application challenge for the new millennium. J Am Coll Surg 2001;192: INVITED COMMENTARY The article by Bodner and colleagues is the largest single series to date detailing the use of robotic technology for the resection of various mediastinal masses. The authors utilize the DaVinci system (Surgical Intuitive Inc., Mountain View, CA), which combines the remote control console, the enhanced three-dimensional magnification technology, and multi-degree of freedom robotic instrumentation. The majority of the patients described in their series involve removal of the thymus gland. The intraoperative and perioperative course are quite acceptable and certainly laudable for an initial series with a complex new technology. Others have documented single case reports or several cases attesting to safety and feasibility [1]. Long-term follow-up will provide further support for the efficacy of this technique but insofar as the authors adhere to the usual principles of surgical resection for tumors in general or thymus in the case of myasthenia gravis then the results should be similar to open techniques. As with other minimally invasive techniques, benefit to the patient will come from earlier recovery including return to full activity and less pain-related morbidity. The absolute clarity of this in the field of gallbladder surgery is such that laparoscopic cholecystectomy is the procedure of choice. In the field of thoracic surgery thoracoscopic lung or pleural biopsy it is the standard approach. Lobectomy for lung cancer has been performed in a number of centers utilizing a purely thoracoscopic approach (no rib spreading, individual hilar vessel, airway and nodal dissection). An NCI-sponsored prospective, multi-institutional trial (CALGB 39802) reported positive results at a recent meeting of ASCO [2]. On the other hand, in this issue of The Annals of Thoracic Surgery Bodner and colleagues report results of surgery for thymic disease. Myasthenia gravis is poorly understood with variable indications for surgery. Thymoma is a slowly growing tumor with recurrences that can occur 5 to 10 years following surgery. As a result the follow-up for these patients will need to be protracted to prove efficacy. The challenge to those leading the field of robotic surgery will be to document the benefit of rather costly technology particularly when the thoracoscopic approach for each of these procedures has been carried out safely and with good intermediate-term follow-up. The incision size is the same for both robotic and thoracoscopic surgery and each should avoid rib-spreading so the 2004 by The Society of Thoracic Surgeons /04/$30.00 Published by Elsevier Inc doi: /j.athoracsur