Surgical techniques for securing the surgical field in thoracoscopic anterior mediastinal tumor resection

Introduction

Traditionally, surgeries for anterior mediastinal diseases were performed through large incisions such as median sternotomy, hemi-clamshell, and clamshell incisions (1). Since the early 1990s, endoscopic surgeries have been initiated in various surgical fields, and with the advancement of technology, interest in minimally invasive surgeries has spread worldwide.

A variety of advanced, less invasive surgical techniques for performing a thymectomy have been elaborated upon in medical literature. These include video-assisted thoracoscopic surgery (VATS) thymectomy, as documented in source (2), the subxiphoid approach to thymectomy detailed in source (3), an innovative subxiphoid single-port thymectomy technique highlighted in source (4), and the cutting-edge robotic thymectomy discussed in sources (5,6). These sophisticated methods offer numerous patient-centric advantages. They are associated with superior aesthetic outcomes post-surgery, significantly diminished pain following the procedure, and a markedly abbreviated recovery period in the hospital. Additionally, patients benefit from a swifter resumption of their routine activities. The minimally invasive nature of these procedures also means there is typically less bleeding during surgery, and they carry a lower risk of postoperative complications.

Thoracoscopic surgeries are also being performed in many thoracic surgery facilities. In our department, thoracoscopic mediastinal tumor resection was initiated in 1997, and robot-assisted mediastinal tumor resection was initiated in 2021. When considering the surgical approach for anterior mediastinal tumors, it is necessary to fully evaluate tumor size, tumor location, and the existence of the tumor invasion to other organs. Securing the surgical field is extremely important, especially when dissecting the upper pole of the thymus in extended thymectomy or tumors located on the cranial side to the innominate vein. Our department mainly adopts a lateral thoracic approach and performs surgeries with various modifications. This manuscript is written following the SUPER reporting checklist (available at https://vats.amegroups.com/article/view/10.21037/vats-23-72/rc).

Preoperative preparations and requirements

The patient is mainly placed in the supine position, and a unilateral intercostal approach is adopted depending on the location of the tumor. In the case of extended thymectomy, ports are also placed on the contralateral side (Figure 1). An access port for carbon dioxide (CO₂) insufflation is inserted in the fifth intercostal space of the anterior axillary line on the surgical side, and tumor resection or thymectomy is performed with access through three ports. Because of a solo surgery by the operator, an assistant port is added when inexperienced operators perform the surgical procedure.

Figure 1 Approach for extended thymectomy in our department. The surgery is performed from the right side, and a port is added to manipulate the left side. The wire wound does not require dressing. No dressings are required for the wire wound.

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was approved by the ethics committee of Yamagata University Faculty of Medicine (Approval No. 2023-30) and informed consent was obtained from all individual participants.

Step-by step description

Surgical procedure

Indication

In determining the indication for thoracoscopic surgery, we use magnetic resonance imaging (MRI) scans to evaluate the nature of the tumor in addition to computed tomography (CT) images. Solid mediastinal tumors 5 cm in size and without major vascular invasion are indicated for thoracoscopic surgery. Recently, we have not been actively indicating surgery for suspicion of benign mediastinal cysts. However, even with cysts, surgery would be considered if there is a growing pattern during observation.

Approach

One-lung ventilation is introduced in general anesthesia. The patient is mainly placed supine, and we do not add any rotation. A unilateral intercostal approach is adopted according to the location of the tumor. A skin incision of 0.5 cm, 0.5 cm, and 2 cm in the anterior axillary line’s 3rd, 4th, and 5th intercostal space is made. In the case of extended thymectomy, with the concern of manipulating the upper pole of the thymus or contralateral phrenic nerve, ports are added on the contralateral side (Figure 1). Mainly, tumor resection or thymectomy is performed with access through three ports. Because of a solo surgery by the operator, an assistant port is added when inexperienced operators perform the surgical procedure.

Postoperative considerations and tasks

Patients typically regain consciousness and are extubated in the operating room. Following a necessary observation period, they are either returned to the ward or, in specific cases such as myasthenia gravis (MG), moved to the intensive care unit (ICU) for further monitoring.

The chest drain is removed once the post-surgical chest X-ray presents the expected results and the volume of pleural fluid is within acceptable limits, usually within 24 hours post-operation. Patients are typically discharged 1–4 days after the surgery.

Tips and pearls

CO₂ insufflation method (7)

The thoracic cavity is closed using an access port for CO₂ insufflation. CO₂ is insufflated to create a positive pressure of 5–8 mmHg in the thoracic cavity. Since hypotension may occur due to artificial pneumothorax, pressure settings are adjusted in collaboration with the anesthesiologist. Recently, we have been using the AirSeal^® system (CONMED, NY, USA) for CO₂ insufflation. This dedicated access port has a three-hole structure, each of which plays a role in

• Suction of CO₂ in the thoracic cavity;
• Recirculation of CO₂ filtered by the machine body into the thoracic cavity and;
• Sensing the pressure in the thoracic cavity in real time and appropriately supplying CO₂.

The AirSeal^® system ensures that instruments and the endoscope inserted into the surgical field are automatically enveloped in airflow. This airflow allows for the exchange of surgical instruments, camera cleaning, and aspiration of the surgical field without destabilizing the pneumothorax pressure. It is believed to reduce the fogging of the endoscope more effectively than conventional artificial pneumothorax devices. It is expected to prevent the patient’s absorption of harmful chemicals in surgical smoke and avoid contamination of the operating room through continuous circulatory smoke evacuation. The constantly circulating smoke exhaust could clear the harmful chemicals in surgical smoke and contaminate the operating room (8,9).

There is a disadvantage to the air sealing system. Air sealing costs 3–4 times more than conventional insufflation. The cost-effectiveness must be considered at each facility.

Sternum lifting method (10)

This method combines CO₂ insufflation to secure the field of view for the superior pole of the thymus in extended thymectomy. Additionally, a 19-gauge needle of the LAPA-HER-CLOSURE (Hakko Medical Device Division, Tokyo, Japan) (Figure 2) used in laparoscopic pediatric inguinal hernia surgery is inserted from the outside of the body into the thoracic cavity at the height of the sternal manubrium (mainly the first intercostal space). Both ends of the Matsuda wire (Matsuda Medical Instruments Co., Ltd., Saitama, Japan) guided from the port are held and guided to the outside of the body (Figure 3). Matsuda wire is retracted with a lifting device to lift the sternum. This method does not require additional incisions, suturing of the wire insertion site, or dressing. Thoracoscopy helps to prevent the injury of the internal thoracic artery (Videos 1,2). In our hospital, when performing thoracoscopic procedures, we have a sternotomy instrument, which includes a wire cutter on standby for emergencies.

Figure 2 Instruments used for traction. Top: LAPA-HER-CLOSURE. Bottom: Matsuda wire.

Figure 3 The inserted LAPA-HER-CLOSURE grasps the Matsuda wire guided from the outside and guides it to the outside. The sternum is lifted by traction with the elevator. Dotted line: the space on the apical area of the innominate vein is enlarged; blue arrow: direction of wire elevation; white dotted arrow: the degree of sternal elevation is indicated; white arrow: Matsuda wire.

If a sternotomy is needed, an urgent conversion is possible.

Retrieving the specimen

The resected specimen is removed from the body using a polyurethane material retrieval bag. By using the bag, specimens can be shrunk and removed.

However, we sometimes remove the specimen for large, solid tumors by slightly extending the wound.

Discussion

There are options to approach anterior mediastinal tumors thoracoscopically: (I) cervical, (II) subxiphoid, and (III) lateral approaches and the combinations approach. It should be considered depending on the case. The cervical approach was first reported in 1988 as one of the approaches for extended thymectomy for MG (10). This method secures the surgical field by lifting the sternum from the cervical incision and performing the surgery. This method has the advantage of less pain due to the absence of intercostal nerve damage caused by intercostal manipulation, while securing the surgical field is challenging, and experience is required for operability. The subxiphoid approach was reported in 1999 (3) and is now widely performed with the spread of single-port (11) and robotic surgeries (12). Like the cervical approach, this method is considered to have less pain due to the absence of intercostal nerve damage. Initially, it needed to be more generalized due to the difficulty in securing the field of view and the need for experience in operation. However, CO₂ insufflation and sternal lifting method have been established, and robotic surgery has utilized the technique (13). The lateral thoracic approach is considered most familiar to thoracic surgeons (14). It is an excellent advantage of the approach that surgeons can operate within the most familiar surgical field.

On the other hand, intercostal nerve damage-induced pain is inevitable in these cases. In our department, while we mainly adopt the lateral approach, the disadvantage of this procedure is the difficulty of securing the surgical field of the upper mediastinum and the contralateral phrenic nerve. Therefore, we adopted the sternum lifting method and CO₂ insufflation method.

From 2012 to 2022, seventeen cases have been operated using the sternum lifting method and CO₂ insufflation. The median operative time was 171 minutes, and no perioperative complications have occurred using this method. Fortunately, there have been no cases of open conversion. The median length of stay was four days. R0 surgery was achieved in all cases.

Securing some good surgical fields with CO₂ insufflation alone may be possible.

However, we believe it is essential to secure the surgical field around the upper pole to dissect the upper pole of the thymus adequately, and we use this sternal suspension technique in conjunction with thymectomy, especially for extended thymectomies.

However, to avoid creating a large wound or increasing the number of wounds due to the lifting, we adopted this method to ensure both the cosmetic aspect and the effectiveness of the lifting.

Since this is a study from a single institution, the number of experienced cases is limited. Given the lower rate of perioperative complications, we believe the sternum lifting method and CO₂ insufflation technique are safe and feasible for anterior mediastinum surgery.

Our sternum lifting technique utilizes a thin wire for elevation, which does not require suturing for the closure of the incision. We believe this is also highly advantageous from an aesthetic standpoint.

Conclusions

We reported the modifications and practice of minimally invasive surgery for anterior mediastinal diseases in our department. Even with a lateral approach, it was possible to perform surgery safely and with a good field of view by using CO₂ insufflation and our sternum lifting method as needed, according to the case.

Acknowledgments

The results of this surgical procedure were previously reported and published in Kyobu Geka 2023 Jul;76(7):540-545 (article in Japanese).

Funding: None.

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://vats.amegroups.com/article/view/10.21037/vats-23-72/rc

Peer Review File: Available at https://vats.amegroups.com/article/view/10.21037/vats-23-72/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://vats.amegroups.com/article/view/10.21037/vats-23-72/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was approved by the ethics committee of Yamagata University Faculty of Medicine (Approval No. 2023-30) and informed consent was obtained from all individual participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Limmer S, Merz H, Kujath P. Giant thymoma in the anterior-inferior mediastinum. Interact Cardiovasc Thorac Surg 2010;10:451-3. [Crossref] [PubMed]
2. Nakagiri T, Inoue M, Shintani Y, et al. Improved procedures and comparative results for video-assisted thoracoscopic extended thymectomy for myasthenia gravis. Surg Endosc 2015;29:2859-65. [Crossref] [PubMed]
3. Kido T, Hazama K, Inoue Y, et al. Resection of anterior mediastinal masses through an infrasternal approach. Ann Thorac Surg 1999;67:263-5. [Crossref] [PubMed]
4. Suda T, Hachimaru A, Tochii D, et al. Video-assisted thoracoscopic thymectomy versus subxiphoid single-port thymectomy: initial results†. Eur J Cardiothorac Surg 2016;49:i54-8. [PubMed]
5. Rueckert J, Swierzy M, Badakhshi H, et al. Robotic-assisted thymectomy: surgical procedure and results. Thorac Cardiovasc Surg 2015;63:194-200. [Crossref] [PubMed]
6. Suda T, Kaneda S, Hachimaru A, et al. Thymectomy via a subxiphoid approach: single-port and robot-assisted. J Thorac Dis 2016;8:S265-71. [PubMed]
7. Mizuno K, Tatematsu T, Oda R, et al. Video-assisted thoracoscopic extended thymectomy while using the carbon dioxide insufflation. Kyobu Geka 2012;65:791-4. [PubMed]
8. Nepple KG, Kallogjeri D, Bhayani SB. Benchtop evaluation of pressure barrier insufflator and standard insufflator systems. Surg Endosc 2013;27:333-8. [Crossref] [PubMed]
9. Balayssac D, Selvy M, Martelin A, et al. Clinical and Organizational Impact of the AIRSEAL(®) Insufflation System During Laparoscopic Surgery: A Systematic Review. World J Surg 2021;45:705-18. [Crossref] [PubMed]
10. Cooper JD, Al-Jilaihawa AN, Pearson FG, et al. An improved technique to facilitate transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 1988;45:242-7. [Crossref] [PubMed]
11. Suda T, Sugimura H, Tochii D, et al. Single-port thymectomy through an infrasternal approach. Ann Thorac Surg 2012;93:334-6. [Crossref] [PubMed]
12. Suda T, Tochii D, Tochii S, et al. Trans-subxiphoid robotic thymectomy. Interact Cardiovasc Thorac Surg 2015;20:669-71. [Crossref] [PubMed]
13. Shiono H. Anterior chest wall lifting methods for mediastinal approach-literature review. Mediastinum 2022;6:24. [Crossref] [PubMed]
14. Landreneau RJ, Dowling RD, Castillo WM, et al. Thoracoscopic resection of an anterior mediastinal tumor. Ann Thorac Surg 1992;54:142-4. [Crossref] [PubMed]