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Ann Thorac Surg 2008;85:S768-S771. doi:10.1016/j.athoracsur.2007.11.079
© 2008 The Society of Thoracic Surgeons
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Supplement: The Minimally Invasive Thoracic Surgery Summit

Video-Assisted Thoracoscopic Surgery versus Robotic-Assisted Thoracoscopic Surgery Thymectomy

Florian Augustin, MD, Thomas Schmid, MD, Michael Sieb, MD, Paolo Lucciarini, MD, Johannes Bodner, MD*

Clinical Department of General and Transplant Surgery, Innsbruck Medical University, Innsbruck, Austria

* Address correspondence to Dr Bodner, Department of General and Transplant Surgery, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria (Email: Johannes.bodner{at}i-med.ac.at).

Presented at the Minimally Invasive Thoracic Surgery Summit, New York, NY, June 8–9, 2007.


   Introduction
Top
 Introduction
Material and Methods
 Results
 Discussion
 References
 
The correct treatment of diseases of the thymic gland has remained a matter of debate in thoracic surgery. Indications for thymectomy primarily include suspected thymoma, myasthenia gravis with and without thymoma, and thymic cysts [1–4].

Regardless of the underlying disease indicating thymectomy, complete removal of the entire thymus is always mandatory because of potentially ectopic thymic tissue. This is not uniformly achieved by all the approaches used worldwide. Thus, the optimal surgical approach—combining a high degree of resection of the thymic gland and its perithymic fat tissue with low surgical invasiveness—is still controversial [5–8].

The introduction of complete robotic surgical systems in the late 1990s contributed to the field of minimally invasive surgery. It soon became obvious that these devices are most advantageous in tiny and difficult to reach anatomic regions. The mediastinum has thus become a hot spot for thoracic surgeons using robotic assistance, and procedures like thymectomy, thymusectomy, resection of paravertebral tumors or ectopic (para-) thyroidectomy have been shown to be feasible and safe when performed with robotic assistance [9–11].

Innsbruck Medical University Hospital purchased a 3-arm da Vinci operating robot (Intuitive Surgical Inc, Mountain View, CA) in June 2001; to date, 32 robotic thymectomy procedures have been performed. Written informed consent was obtained from all patients. Use of the da Vinci system was approved by the local ethics committee. A review of the patient charts back to 1999 shows that only four thoracoscopic thymectomies were performed with a conventional video-assisted thoracoscopic surgical approach (VATS); therefore, direct comparison of our results for the two types of thymectomy is not appropriate.

A benefit of the robotic-assisted thoracoscopic surgical (RATS) approach to thymectomy compared with the conventional VATS approach has not yet been proven. When combining our institutional experience with the robotic approach and the recent literature on VATS, we arrive at a critical interim appraisal of RATS vs VATS thymectomy.


   Material and Methods
Top
 Introduction
 Material and Methods
Results
 Discussion
 References
 
Robotic-Assisted Thymectomy
After general anesthesia is initiated with a volatile anesthetic (sevoflurane), an opioid (remifentanil), and propofol, patients are intubated with a double-lumen tube for selective single-lung ventilation. Standard patient positioning is an incomplete (side up at a 30° angle) left lateral decubitus position. The right arm is positioned at the patient’s side as far back as possible to gain enough space for the robotic arms (Fig 1). Three trocars are placed: the right and the left are the working ports and the trocar in the mid-position is the camera port.


Figure 1
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  		Fig 1. Detailed description of a robotic thymectomy: (top) adjustment in the operating room, (bottom left) patient positioning, and (bottom right) trocar placement.

 
An extended thymectomy with en bloc resection of the anterior mediastinal fat tissue, including the thymus, is performed [12]. The adipose tissue around the upper poles of the thymus, around both brachiocephalic veins and on the pericardium, is meticulously dissected. Dissection limits are the diaphragm caudally, the thyroid gland cranially, and the phrenic nerves laterally [9].

The port for the robotic endoscope is positioned in the sixth intercostal space in the middle axillary line. The camera is inserted and the 2 robotic instrument ports are visually guided to the third and sixth intercostal spaces, one hand’s breadth left and right of the camera trocar. Dissection is performed with a robotic cautery hook in the right and a Cadiere forceps (Intuitive Surgical Inc, Mountain View, CA) in the left hand, starting medial to the right phrenic nerve from cranial to caudal. Dissection is then continued to the substernal region, and the contralateral pleural cavity is opened.

The thymus is dissected free from the pericardium, and preparation proceeds as far as the thymic veins. This is followed by dissection of the right and left upper horns and transection of the thymic vein(s). Larger vessels are clipped, and smaller ones are sealed 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. The specimen is removed in an Endobag (US Surgical, Norwalk, CT) inserted through the auxiliary port. One chest tube is placed in the right pleural cavity, and patients are extubated while still in the operating room.

To locate evidence-based data on RATS and VATS thymectomy, a literature research reviewing the recent literature filed on PubMed (The New York Academy of Sciences) was performed using the key words thymectomy, thoracoscopy, VATS, and robotic.


   Results
Top
 Introduction
 Material and Methods
 Results
Discussion
 References
 
Institutional Robotic Series
In the 32 institutional robotic thymectomies reported to date, no death and no major intraoperative or postoperative morbidity occurred. One patient (3%) was converted to thoracotomy owing to minor bleeding from the right internal thoracic vein. Minor postoperative complications included a wound infection at a port site and a patient with a peripheral pulmonary embolism. No relevant intraoperative blood loss occurred. Chest tubes were removed on postoperative day 2 (range, 2 to 6 days). Median hospital stay was 6 days (range, 4 to 15 days).

In a subgroup of 9 thymoma patients, 6 at Masaoka stage I and 3 at Masaoka stage IIa, histology confirmed the resection margins to be free of tumor (R0). Median size of the thymoma was 30 mm (range, 20 to 50 mm). At a mean follow-up of 25 months (range, 2 to 49 months), no clinical or radiologic sign of tumor recurrence has been noted in any of the thymoma patients.

Literature Research
The literature contains 150 published studies and reports demonstrating that the VATS approach for thymectomy is a feasible and technically safe procedure with very low morbidity. Its results in myasthenia gravis are comparable with the open approach, with a positive effect on postoperative pulmonary function [13]. However, concerns still surround application of the VATS approach in thymoma patients [14].

The feasibility and safety of RATS thymectomy with the daVinci system have been proven by 10 studies published to date. In this study, we have compared RATS and VATS. Table 1 summarizes a comparison of the recent literature, emphasizing the difference between open and minimally invasive access for thymectomy [15–30]. Because many VATS studies compare thoracoscopic and open procedures, the results for the transsternal operation are also shown.


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  		Table 1 Comparison of Video-Assisted and Robotic-Assisted Thoracoscopic Thymectomy From the Literature
 

   Discussion
Top
 Introduction
 Material and Methods
 Results
 Discussion
References
 
Thymectomy is indicated in various diseases, including thymoma, thymic cysts, and thymus carcinoma, and is also a therapeutic option in adjunct to medical management in myasthenia gravis. The surgical approach to thymectomy remains controversial, and a variety of different techniques have been introduced in recent decades, each with its advantages and disadvantages. Common characteristics of any kind of minimally invasive approach are reduced patient morbidity, mortality, and postoperative pain; shorter postoperative hospital stay and recovery; and lower wound infection rates. These obvious advantages of minimally invasive surgery have induced greater acceptability, especially among patients with myasthenia gravis and the physicians who treat them, and have thus increased the total number of thymectomies being performed.

The VATS approach combines the advantages of minimally invasive techniques with an excellent view of the anterior mediastinum. This permits an extended thymectomy to be performed, similar to the one in the transsternal approach. The most evident benefits of a VATS approach are decreased estimated blood loss (7.5 to 82.5 mL vs 52.5 to 557.1 mL) [15–17], decreased length of hospital stay (1.5 to 6.1 days vs 5.6 to 26.9 days) [15,18–21], improved cosmetic results, and faster recovery and social reintegration with lower pain scores (median visual analog scale score, 1.9 to 3.1 vs 4.8 to 6.1) [16, 21, 30].

Moreover, the results obtained with the minimally invasive transcervical, VATS, or combined approach have been proven to be comparable with the significantly more invasive transsternal approach in terms of remission or clinical improvement of myasthenic symptoms, thus suggesting that any approach is effective if thymectomy is radical and extended to the perithymic tissue [15–18, 30].

Compared with VATS, RATS thymectomy has a similar median length of hospital stay of 2 to 5 days. To date, no data on intraoperative blood loss or postoperative pain scores are available for the robotic approach.

Published operative times for VATS thymectomy range from a median 90 minutes to 268.3 minutes. This wide range may be caused by learning curves, different frequencies among various institutions, and differences in patients and diseases enrolled. In 2005, Savitt and colleagues [26] reported 15 successful RATS thymectomies with a mean operative time of 96 minutes (range, 62 to 132 minutes). In a series of patients with myasthenia gravis operated on robotically, Rea and colleagues [27] reported a mean operative time of 120 minutes (range, 60 to 240 minutes). The median operative time in our own first series of extended thymectomies was 150 minutes (range, 104 to 223 minutes) [24], but dropped with increasing experience to 127 minutes (range, 54 to 314 minutes in 2006 [25]. In sum, overall operating time seems to be shorter in the RATS group.

Because the high costs are one of the main points of criticism voiced in connection with robotic-assisted operations, we recently evaluated the procedural costs of thymectomy for various minimally invasive approaches. Use of the robot is significantly more expensive; we demonstrated additional costs of about 91% compared with conventional VATS (Fig 2). These extra costs are primarily caused by the expensive robotic instruments, which can be reused only a limited number of times [24].


Figure 2
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  		Fig 2. Overall costs of thymectomy. Procedural costs of video-assisted thorascopic surgery (VATS) vs robotic-assisted thoracoscopic (RATS) thymectomy.

 
Because all published results do not favor any of the minimally invasive techniques and no prospective randomized trials are available, only general statements can be made about why we prefer the robotic approach. The upper mediastinum is an anatomic area that is difficult to reach when approached by conventional thoracoscopy. Working thoracoscopically in an anatomic region with vulnerable large vessels and nerves certainly poses a potential risk: the image of the operating field on the monitor is only two-dimensional with a loss of depth perception, the surgeon’s hand movements have to be executed counteractively to the direction the instruments are intended to take inside the pleural cavity, and the surgeon’s hand tremor is increased by thoracoscopic instruments. This makes it particularly difficult to dissect the thymus in the neck region and to reach the perithymic fat in the contralateral hemithorax [27]. Needless to say, advanced surgical skills are required.

Robotic technology was introduced into surgical medicine to overcome these obvious limitations of conventional minimally invasive surgery. The da Vinci surgical robotic system offers advanced visual control and superior maneuverability of the surgical instruments, and hand movements in the grips of the console are naturally and intuitively transmitted to the robot’s instruments. With 7° of freedom in movement of the instrument tip and a possible rotation of 360°, it is superior to a surgeon’s hand in open surgery, thus improving maneuverability around anatomic structures [31]. This facilitates gentle and precise dissection within a small, fixed three-dimensional and remote area.

To date, no prospective randomized trials comparing outcomes after VATS and RATS thymectomy have been published; thus at this stage, reliance on impressions and personal feelings may still be tolerable. Because of the improved maneuverability found with RATS, Savitt and colleagues [26] stated that robotic surgery is more suitable than VATS for an extended thymectomy. Further definite pros for the robotic approach seem to be the easier dissection of the upper horns, the controlled ligation of the thymic veins, and the excellent access to the entire anterior mediastinum from a single-sided approach.

This appraisal remains to be verified. But even then, why use a cumbersome robotic system at significantly higher costs if VATS thymectomy is feasible and safe and yields excellent long-term results? Only when randomized trials are performed, will we learn the answer.


   References
Top
 Introduction
 Material and Methods
 Results
 Discussion
 References
 

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