The composition of RAS

As the most widely used robotic surgical system, the DVSS is composed of three separate components: the surgeon console, patient cart, and vision cart. The surgeon sits at the console and remotely controls the robotic arms beside the bed, manipulating surgical instruments to perform complex surgical procedures in a minimally invasive way. The patient cart supports the instrument arms and the endoscopic arm to ensure stable imaging and operation. The assistant is next to the patient cart, responsible for the installation and replacement of surgical instruments, supervising the use of instruments, and ensuring the safety of patients. The vision cart contains the core processor and image processing equipment of the surgical robot, and the endoscope can form a magnified three-dimensional (3D) stereoscopic image, allowing the surgeon to accurately distinguish the internal anatomy and perform delicate operations. In addition, devices such as function confirmation, intelligent self-inspection, and audio-visual communication help to communicate with each other and ensure the safety of patients.

There are also some robotic systems less widely used than the DVSS but also have potential for future development: the Telelap ALF-X robot consists of an open console with eye tracking, hands with tactile feedback, and robotic arms beside the bed; the Avatera robot has a closed console with microscope-like oculars and four arms on the side cart connected to the 5 mm instruments with 6 df; and the ReVO-I robot consists of an open console and four robotic arms on a cart.4 5 The Hugo robotic surgical system is the latest robotic surgical system, including a surgical tower, console, surgical arm, and cart with a compact and mobile platform design, which can be moved throughout the hospital, reducing the cost of purchasing a robotic system for each operating room.6 7 The Hugo robotic surgical system also has an upgradable system, which can be upgraded in time with the development of technology without requiring the hospital to replace the entire system. At present, it is mainly used in adult urology and gynecology.8 9

Advantages of RAS in children

Aiming at the small and complex anatomy of children, binocular loupes are often used in open surgery to magnify the fine structures in the field of view. Although the traditional laparoscopic endoscope has a magnifying effect, the unique advantages of the robot’s 3D magnification can establish the surgeon’s stereoscopic visualization, increasing the depth perception of the operator.10 The robot is also equipped with motion scaling and tremor-filtering functions, avoiding the tiny movements of the hand and making the operation stable and precise.11 At the same time, compared with the traditional laparoscopic 4 df, robotic surgical instruments with 7 df further eliminate tool constraints, which simplifies sutures and ligations in small areas.12 The robot also has advantages in the details: the tip of the instrument moves in the same direction as the operator’s hand, which is easier to learn than traditional laparoscopy; a small space leads to slower replacement of instruments, while robotic instruments can reach their original positions quickly and accurately, improving a certain efficiency; and the ergonomic sitting position of the console allows the operator to get some rest.13

Due to the small body size of children, especially neonates and infants, conventional laparoscopy often presents problems such as small operating space, poor visualization effect and limited freedom when involving complex and difficult dissections. However, with the designs described above, robots can overcome these limitations and achieve a more complete and efficient solution. For diseases such as Hirschsprung’s disease (HSCR) and anorectal malformation (ARM), the operative field of vision is limited, and the operation is difficult. However, the robot provides the surgeon with extensive visualization of the deep pelvis, 3D imaging and a high df, so that the surgeon can carry out resection and reconstruction surgery more accurate in a limited space.14 15 With the application of robots in children, new opportunities will be provided for these complicated surgeries.

Restrictions of RAS in children

The shortcomings of RAS are as follows: (1) high cost16; (2) due to the lack of tactile feedback, the operator has to rely on previous visual judgment and experience in anatomy10; (3) the larger size of the instrument also affects the application of RAS in children. Ballouhey et al17 found that robotic surgery presents greater technical limitations in children under 3.0 kg. Taking the DVSS as an example, there are currently two types of surgical instruments with diameters of 5 mm and 8 mm, both of which are larger than the traditional laparoscopy with a diameter of 3 mm. The lack of commercially available 3 mm instruments is a significant limitation for the robot, hindering its use in infants.16 (4) The Da Vinci manufacturer recommends an 8 cm distance between each port, which is obviously difficult in children. However, Ballouhey et al17 showed that a distance of 5–6 cm is acceptable because the distance between the ports increases after inflation. Navarrete Arellano and Garibay González18 performed various operations on the young infants with a 3 cm interval between each trocar without any problems. (5) Anesthesia in minimally invasive endoscopic surgery cannot be ignored, especially for infants and neonates with poor cardiopulmonary tolerance and strong peritoneal absorption, which can easily absorb CO₂ and lead to hypercapnia, affecting cardiopulmonary and brain functions.19 20 Therefore, it is necessary to accurately regulate airway inflation pressure and oxygen concentration, which is also a major challenge in pediatric surgery.

The learning curve of RAS

The robot’s learning curve (LC) is also worth mentioning. The LC represents how the ability to solve problems changes over time and experience. Some researchers believe that because the intuitive symmetric motion of the robot system is consistent with the surgeon’s hand, while traditional laparoscopy requires reverse motion, the LC of RAS is shorter, and the surgeons can reach the comfort level faster than laparoscopic surgery.21 22 Pio et al conducted the first systematic review of robot’s LC in pediatric surgery, involving urology, general surgery and otolaryngology.23 The total operative time, including console time and docking time, was most commonly used to assess the LC. In addition, some reports included intraoperative and postoperative complications, and length of hospital stay as evaluation criteria. The overall analysis showed that the operation time decreased as the number of cases performed by the surgeon increased, eventually leveling off, and in some cases, even approaching the time of conventional laparotomy. Therefore, they believed that surgeons transitioning from open surgery to robotic surgery can achieve professional levels in established robotic surgery programs under the guidance of trained robotic teams. Surgeons with or without experience in laparoscopic or robotic surgery can perform robotic surgery independently, and experience in robotic or laparoscopic surgery can make LC steep. However, they also indicated that due to the differences in the backgrounds of surgeons, the characteristics of patients and the types of surgeries, as well as different study designs and statistical analysis methods, multiple parameters related to proficiency should be considered in the assessment of LC. However, there is no consensus on the assessment criteria of LC in the literature.

Urology

Robot-assisted laparoscopic surgery is currently the most widely applied in urology.24 Robot-assisted pyeloplasty is a major surgical procedure in the field of pediatric urology, and other robotic surgeries, such as partial or complete nephrectomy, ureterostomy, ureteral reimplantation, bladder reconstruction, etc, and has also been proven to be safe and effective.25–27 Navarrete Arellano and Garibay González reported a prospective observational study including 186 children who underwent RAS from 2015 to 2018.18 There were 91 cases in urology department. Pyeloplasty, nephrectomy and ureteral replantation were successfully completed, and the overall postoperative recovery was good. The study showed that robotic surgery is safe and effective for children and can perform a variety of complex surgeries. Ballouhey et al prospectively collected and retrospectively analyzed perioperative and intraoperative data of 117 children undergoing various robotic urology procedures. The results showed that only two cases were converted to open surgery due to equipment problems, proving that robotic surgery is safe and feasible in pediatric urology.17 In that study, children were divided into two groups (<15 kg and >15 kg), and no significant difference in the average operation time, hospital stay, and the postoperative follow-up results were found between the two groups. Therefore, the authors believed that RAS can be carried out on younger children with the same safety and efficiency as older children, and the robotic LC is faster than traditional laparoscopy.17

Although the cost of robotic surgery is higher than that of open surgery, there are documented reports of higher postoperative satisfaction and quality of life in patients.28 A large multinational and multicenter study comparing the efficacy of traditional laparoscopic and robot-assisted pyeloplasty showed that both minimally invasive methods are safe and effective for the treatment of obstruction at the ureteropelvic junction in children, but the length of hospital stay after robotic surgery was shorter and the incidence of postoperative complications was lower.29 A meta-analysis comparing robotic surgery with open and laparoscopic approaches also found that robot-assisted pyeloplasty in pediatric patients resulted in shorter hospital stays, lower blood loss and analgesic need compared with traditional laparoscopic or open pyeloplasty.30 However, higher quality evidence from prospective observational studies and clinical trials is needed for further cost-effectiveness analysis. Robots are the main development field of urology at present. The advantages of various surgical procedures in pediatric urology in terms of safety and prognosis are gradually recognized, allowing surgeons to constantly innovate, break through the inherent specific technology, and challenge the complex surgery that cannot be completed by traditional laparoscopy.

General surgery

At present, robot-assisted fundoplication for the treatment of hiatal hernia has been widely used and has been proven safe and effective by many institutions.17 18 21 31 In addition, RAS has involved more complex traditional laparoscopic surgery in pediatric gastrointestinal surgery, such as laparoscopic megacolon radical resection and laparoscopic anoplasty. Due to the unique advantages of the robotic system, the development of such operations is smoother. Accurate pelvic anatomy is an important link between HSCR and ARM surgery, which can reduce damage to pelvic nerve as much as possible, and reduce the resulting rectal and anal dysfunction,. Due to overcoming the limitations of limited space and poor visualization in the depths of the pelvis, RAS can be applied to ideally identify and dissociate the colon and rectum in the pelvic cavity with the advantages of 3D visualization and flexible operation, to perform a more complete rectal anatomy and to reduce damage to the pelvic nerve, which is of great importance to reduce postoperative complications.32 33 Moreover, RAS is suitable for different surgical procedures of HSCR, whether Soave surgery or Swenson surgery, which can be carried out safely and effectively. In 2011, Hebra et al first reported the robot-assisted Swenson procedure in 12 infants with HSCR.34 In 2017, Mattioli et al reported three cases of robot-assisted Soave procedures for HSCR in children aged 5 years, 16 years and 20 months.32 According to the postoperative follow-up data of different centers, the clinical results of RAS are satisfactory, with no postoperative incontinence, good defecation function, and a low incidence of postoperative enterocolitis.32–35

Prospective studies of small samples found that Soave surgery performed by RAS could be successfully completed without intraoperative complications, and the incidence of postoperative complications was significantly reduced.36 Long-term follow-up results also showed that robot-assisted Soave procedure can be used for the treatment of infant HSCR, which is safe, efficient and has a good long-term prognosis.37 It is superior to laparoscopy and laparotomy in avoiding sphincter injury and reducing complications but requires a skilled and excellent team to perform the operation.37 At the same time, with the accumulation of operational experience and improvement of technical level, the age of children treated by robotic surgery for HSCR is getting younger and younger.36 37 The developmental advantages and potential of robotic surgery in the treatment of HSCR still need to be further verified by more prospective studies.

The advantages of robotic pelvic floor anatomy are also conducive to the accurate dissection of fistulas in children with ARM complicated with rectourethral fistula. The robot provides good visualization of the depth of the pelvis while improving reconstruction techniques with excellent dexterity and precision of motion, minimizing nerve around rectum and sphincter trauma and reducing complications, which is important in the surgical treatment of ARMs.38 39 In 2016, Ruiz et al reported a case of a child with anal atresia treated by RAS.15 The operation was successfully completed without any complications, and the child was discharged from the hospital on the 6th day after the operation and had a good follow-up result. However, the overall number of reports is still small, and the experience is still limited at present, which needs to be confirmed in a larger research series.

RAS has also been applied in pediatric hepatobiliary diseases. Compared with laparoscopy, the robot improves the visualization and identification of the hilum hepatis, reduces the difficulty of anatomy, greatly helps the anatomy of the hepatobiliary region and the reconstruction of the biliary tract, and shortens the LC of doctors.12 40 In 2006, Woo et al used a robot to treat a child with type I choledochal cyst and completed resection of the choledochal cyst and a Roux-en-Y hepaticojejunostomy, with good follow-up results.40 Later, several centers reported the application of RAS in treating choledochal cysts, and the surgeries were successfully completed with a low incidence of postoperative complications and good follow-up results.41–43 In Chang et al’s report on the robotic treatment of 14 children with choledochal cysts, the first 3 patients had serious technical problems and complications due to lack of experience, but the remaining 11 patients were successfully operated on without any complications after completing systematic training, which showed that the use of robots requires a good and skilled team.44 Although the operation of RAS in the hepatobiliary area has advantages, retrospective analyses between the robot and laparoscopy showed no significant difference in the intraoperative blood loss and the incidence of postoperative complications, and the medical cost of the robot was higher than that of laparoscopy.45 46 Whether robotic and laparoscopic treatment are different in terms of postoperative outcomes, complication rates and long-term prognoses needs to be further compared and evaluated.

Cardiothoracic surgery

In 2004, Bodner et al carried out a series of robotic operations in adult thoracic surgery with good intraoperative and postoperative clinical results, indicating that the robot is safe and effective with accurate dissection in hard-to-reach areas.47 Later, the robot was gradually applied in children’s thoracic surgery to complete precise tissue resection and repair, including resection of mediastinal mass, pulmonary segmentectomy, diaphragmatic plication, diaphragmatic repair, bronchogenic cyst resection and so on.17 18 31 48 However, under the protection of the ribs, the operation space in the thoracic cavity is small, and many organs and complex anatomical structures lead to easy collision of the instruments. At the same time, the cardiopulmonary tolerance of children is worse than that of adults, which leads to the lack of robotic surgery in pediatric cardiothoracic surgery. Ballouhey et al prospectively collected perioperative and intraoperative data on 11 pediatric robotic thoracic surgeries at two pediatric centers and then performed a retrospective analysis comparing operation time, completion rate, length of hospitalization and postoperative complications with thoracoscopic results in the literature.49 The results showed that robotics had similar advantages to thoracoscopy in the removal of mediastinal cysts in older children. They also stated that in neonates, it takes a lot of time to position and place the trocar, and the technology is limited. Currently, there is a lack of evidence that low-weight children, especially neonates, are good candidates for robotic use in thoracic surgery, which needs to be evaluated with more case data.

Robotic surgery in pediatric cardiac surgery is also relatively rare and mainly involves the treatment of congenital heart disease, such as atrial septal defect closure repair and valve replacement. Due to the narrow intercostal space, small thoracic cavity space and relatively large size of robotic devices, the reported pediatric patients are all older children. Thus, the application of robots in infants is still lacking. Onan et al performed robotic surgery on 30 children who were between 13 and 17 years old from 2013 to 2018, including atrial septal defect closure, partial anomalous pulmonary venous connection repair, tricuspid valve annuloplasty and mitral valve replacement.50 All surgeries were successfully performed without conversion, and there were no reoperations or deaths during a mean follow-up of 1.7 years, which confirms that robot-assisted heart surgery is feasible and safe. Gao et al performed robotic surgery on 45 patients with atrial defects and 10 patients with left atrial myxoma.51 The patients ranged in age from 12 to 61 years old, and all patients were successfully resected or repaired without open conversion surgery, death, stroke, or device-related complications, indicating that RAS has no restrictions on the safe resection of left atrial myxoma and repair of atrial defect and has good cosmetic results. Xiao et al reported 160 cases of patients with atrial septal defects treated by RAS, aged 11–66 years, with similar results, without translational thoracotomy or serious complications and good follow-up results.52 Although the robot can complete the precise resection and repair of the thoracic cavity, its development in young children still needs further experience and exploration.

Oncology surgery

For tumor surgery, some tumors are not easily accessible, and intraoperative visual and operational limitations often hinder the progress of traditional minimally invasive surgery and increase the surgical risks.53 Chen et al reported a case of a 3-year-old child with S5 hepatoblastoma undergoing RAS in 2019.12 Intraoperative liver tumor resection was successfully completed, preserving the gall bladder, which preliminarily indicated that robot-assisted partial hepatectomy is feasible, but relevant experience is still limited.

Blanc et al prospectively studied 10 children with cancer aged 3–14 years who underwent robot-assisted nephrectomy between December 2016 and September 2018.54 Three of them were converted to open surgery. All tumors were completely resected without rupture, and the children were stable after the operations. One female patient died of complications of central nervous system metastasis 1 year after surgery during long-term follow-up. There was no difference in age, tumor stage, or operation time between the robotic group and the open approach group, and the hospital stay of the robotic group was shorter than that of the open approach group. The authors suggested that RAS can maintain a clear view of the extent of the tumor, facilitate safe dissection of the injured organ and repair of the diaphragm, and reproduce all the procedures of open surgery. After careful consideration of the indications, a surgical procedure by a highly experienced surgeon may be considered. Then, Blanc et al published a 4-year prospective study on tumor resection of RAS in 2022 and 89 children with abdominal, thoracic, pelvic, and retroperitoneal tumors were enrolled in the study.55 A total of 93 operations were performed to remove 100 tumors. The overall postoperative effect was good, and the complication rate was relatively low. The results showed that robotic surgery is a safe option, but the authors emphasized that indications should be actively discussed and cases should be strictly selected for robotic surgery.

Vatta et al conducted a retrospective analysis of 14 children who received robot-assisted tumor resection.56 The tumors involved included mature teratoma, serous papillary cystadenofibromas of the fallopian tube, ovarian cystadenoma, type 3 sacrococcygeal tumor, neuroblastoma and intermixed ganglioneuroblastoma. All tumors were successfully resected without conversion to open surgery, and no recurrence or complications occurred during follow-up. The results showed that RAS is feasible in pediatric tumors, but they believed that the use of RAS should be limited to selected cases and operated on by trained oncological surgeons. Although robotic surgery has been promoted in adult tumors, there are still many limitations in pediatric tumors. Further innovations in robotic technology may make it more widely used in pediatric tumors.