The utility of RATS in pulmonary segmentectomies has been extensively documented [7,8,9,10,11], and several studies have compared RATS segmentectomy with VATS (Table 5). However, to the best of our knowledge, no previous study has specifically examined the advantages of using a robotic stapler during RATS segmentectomy. Our study demonstrated the safety and efficacy of dividing the intersegmental plane using a robotic stapler in RATS segmentectomy.

In a randomized controlled trial, it was found that division of the intersegmental plane using a stapler reduced postoperative complications compared to division using electrocautery during pulmonary segmentectomy [12]. Moreover, there was no difference in the respiratory function between the electrocautery and stapler groups. Several retrospective studies have also reported a higher incidence of prolonged air leaks in the electrocautery-alone group than in the stapler group, and the use of a stapler did not result in a significant loss of preserved lung volume function compared with electrocautery [13, 14]. Based on these findings, it is likely that the division of the intersegmental plane using a stapler will become the standard practice. Furthermore, as segmentectomy becomes more prevalent, the number of cases that require ipsilateral reoperation after segmentectomy is expected to increase. However, such procedures are often challenging to perform [15]. Specifically, if the segmental plane is dissected by electrocautery and extensively covered with fibrin glue and PGA sheets, adhesions become extensive and severe, thus further complicating reoperation [16, 17].

In the present study, the operative time and blood loss during RATS segmentectomy were significantly lower than those during CVATS. Although most previous studies have reported that the operative time for RATS segmentectomy was either longer or comparable to that for VATS segmentectomy [7, 8, 18], these studies seem to have used hand-held staplers without employing a robotic stapler. The use of a robotic stapler may have contributed to the shorter operative time in RATS. However, many previous reports did not specify whether CVATS or hybrid VATS was performed, whereas this study exclusively compared CVATS with RATS. This could be another contributing factor because the limitation in the stapler insertion direction makes it technically more challenging to use staplers than hybrid VATS.

The postoperative complications following RATS were significantly lower than those following CVATS. In particular, the occurrence of prolonged air leaks was noticeably reduced in RATS compared to CVATS. This can be attributed to several factors, including the ability of RATS to provide precise exposure of hilar structures through enhanced 3D and magnified vision as well as its capacity for accurate dissection along intersegmental lines using the SureForm stapler. One advantage of the SureForm stapler is its increased flexibility during bending. While hand-held staplers allow only 45° to the left and right, SureForm permits bending of up to 60°in all directions, including both the lateral and vertical orientations. This versatility in stapler bending is particularly beneficial because it enables stapling from only one or two ports, even in complex segmentectomies. CO2 insufflation is important for the comfortable use of SureForm because it expands the thoracic cavity and provides a wide working space to effectively utilize SureForm. However, it should be noted that the use of SureForm may pose some technical challenges in patients with a short stature. The stapling site of SureForm must be positioned within the port in the thoracic cavity; however, in individuals with a short stature, the stapling site may sometimes be too close to the port, thus making it difficult to achieve the desired bending of the SureForm stapler.

Several key points were involved in dissecting the intersegmental plane along the correct line. First, it is important to clearly delineate the intersegmental line. Near-infrared fluorescence mapping using ICG has recently been reported as a valuable technique for identifying the intersegmental plane [19, 20]. Near-infrared fluorescence mapping using ICG can be easily performed using a Firefly Fluorescence Imaging camera, which is beneficial during RATS segmentectomies. Additionally, when the intersegmental plane was close to the tumor, we also utilized hook-wire localization. Although the hook itself cannot be visualized, the location of the insertion site of the wire can assist in identifying intersegmental lines, such as when it is difficult to identify intersegmental lines using ICG. In addition, if the hook is confirmed to be included in the resected specimen, it is a marker for tumor resection. Second, to facilitate easy division of the intersegmental plane at the pulmonary hilum using a stapler, it is necessary to adequately dissect the blood vessels and bronchi at the hilum, pushing them as far peripherally as possible using a bipolar device. Utilizing the advantages of the robot, such as 3D visualization and magnification, can help prevent air leakage after the procedure. Third, visualizing the line to be dissected with the robotic stapler involves sufficient traction on the resected vessels and bronchi in the pulmonary hilum. The silk threads used for taping blood vessels and bronchi were intentionally stapled together with these structures using a stapler. These threads were pulled to widen the view of the pulmonary hilum and outline the correct dissection line, as shown in Fig. 1. The retraction arm is utilized to pull these sutures, and it is a useful technique that takes advantage of the features of the robot. The retraction arm could be easily moved in various directions and it did not interfere with the field of view. Instead of pulling the thread, forceps can be used to directly grasp the vessels and bronchi; however, the forceps are in close proximity to the stapler during stapling and interfere with the stapler. Failure to perform these procedures can result in the presence of residual pulmonary hilar structures that should be resected or a narrowing of remaining blood vessels, thus leading to congestion and other complications.

We also compared complex segmentectomies with simple segmentectomies in the RATS cases. Complex segmentectomy is generally considered more technically challenging than simple segmentectomy and presents difficulties in achieving a sufficient surgical margin. However, the operative time, console time, surgical margin, and incidence of perioperative complications were comparable between RATS complex and simple segmentectomy. These findings suggest that RATS complex segmentectomy can be safely performed using a robotic stapler. Complex segmentectomy requires the peripheral dissection of the vascular structures and bronchi within the lung parenchyma, and there is a high risk of structural misidentification. Therefore, whether the vessels and bronchi should be dissected should be carefully determined prior to dissection. To address this, the surrounding vessels and bronchi are exposed as much as possible before dissection, and the vessels and bronchi are dissected after a good understanding of the overall structure. 3D visualization and magnification, which are the advantages of the robot, can help with these procedures.

One of the advantages of RATS portal segmentectomy is its cosmetic aspect. While CVATS and RATS with an assist window usually require a 3 cm or more incision, RATS portal segmentectomy utilizes the minimum necessary incision for lung extraction, resulting in a significantly smaller incision compared to CVATS. Furthermore, in RATS portal complex segmentectomy, where the resected lung is smaller than in RATS portal simple segmentectomy, the maximum incision size is also significantly smaller.

Cost is often cited as a recurring issue in the RATS. In the present study, RATS segmentectomy using a robotic stapler required significantly more staplers than CVATS segmentectomy, thus suggesting that RATS segmentectomy using a robotic stapler costs more than CVATS segmentectomy. However, a reduction in the operative time and postoperative complications may also lead to cost savings. In fact, recent studies comparing the cost of RATS and VATS segmentectomies reported that the costs were comparable between RATS and VATS segmentectomies [8, 21]. Zervos et al. compared the use of robotic and handheld staplers during RATS lobectomy and reported that the robotic stapler significantly reduced perioperative complications, and the total index hospitalization costs were comparable [22]. The reason why a large number of staplers are required in RATS is likely because we use the 45 mm stapler to dissect the intersegmental plane. The SureForm stapler is a disposable product with a maximum capacity of 12 firings and requires the choice of a 45 or 60 mm option. To reduce the number of staplers, both 45 mm and 60 mm SureForm staplers could also be used, but this would incur additional costs for the main unit and may not yield significant cost-saving benefits. Moreover, it is challenging to use the 60 mm SureForm for all vascular and lung dissections, so we exclusively use the 45 mm SureForm stapler. Recently, we have been conserving staplers by ligating the vessels instead of using them because segmentectomies often involve the dissection of small vessels.

This study is associated with several limitations. First, this was a retrospective study, and a prospective randomized study is required in the future. Second, we were not able to compare the effectiveness of the robotic and hand-held staplers in RATS. Third, 21 cases of CVATS were performed by trainees, whereas RATS was performed by only attending surgeons. Therefore, we reanalyzed the surgical outcomes, excluding cases performed by trainee surgeons, as shown in Supplemental Table 2. However, the perioperative results were similar to those of the main analysis even when trainee surgeons were excluded. Finally, the objective of this study was to obtain the short-term perioperative outcomes; a longer follow-up period is necessary to clarify the efficacy of RATS segmentectomy using a robotic stapler.