1. Console setting
9. Clutching
17. Atraumatic handling
2. Docking
10. Instrument names
18. Blunt dissection
3. Robotic trocars
11. Instrument exchange
19. Fine dissection
4. Robotic positioning
12. Fourth arm control
20. Retraction
5. Communication
13. Basic eye-hand coordination
21. Cutting
6. Energy sources
14. Wrist articulation
22. Suturing interrupted
7. Robot component names
15. Depth perception
23. Suturing running
8. Camera
16. Instrument to instrument transfer
Other simulators attempt to create more specialty-specific training. For example, Marecik et al. created a pelvic model to partner with a robotic simulator for colorectal surgery [19]. This allows surgeons to gain experience with robotic setup and use of the console in the context of their practice. Colorectal surgeons can experience proper docking and positioning, use of multiple robotic arms, and dissection between the pelvic sidewall and mesorectum in a simulated total mesorectal excision (TME). The materials to create this simulator (other than the robotic system) are inexpensive and easily obtainable. This provides significant advantages over virtual reality trainers, which are more expensive but have not been shown to offer any advantage in skill acquisition [20].
Other programs focus more heavily on operative technique. An academic MIS fellowship program required a fellow to first demonstrate proficiency in laparoscopy as well as completing 10 h of robotic training sessions before being allowed to operate with the robotic system [21]. The trainee then moved on to the operative portion with robotic-assisted Roux-en-Y gastric bypasses under the guidance of an expert robotic surgeon. Three specific subtasks of increasing difficulty were identified in the procedures. Task A, performing the posterior outer layer of the gastrojejunostomy (GJ) anastomosis, was performed during all 30 procedures. Operative times for this task decreased steadily through all 30 cases. Task B added the anterior outer layer of the GJ anastomosis, and operative times of the 20 cases did not differ significantly from the time of the faculty surgeon. Task C, enterotomy closure of the GIA-stapled inner layer, was performed by the fellow in the final ten cases. Trainee operative times were similar to what faculty times had been during the first ten cases. No patients in this series had any intraoperative complications such as anastomotic leak.
A similar methodology could easily be applied to colorectal surgery. For example, a robotic-assisted laparoscopic low anterior resection (LAR) could be divided into high ligation of the inferior mesenteric artery and mobilization of the descending colon, pelvic dissection and rectal mobilization, and colorectal anastomosis. This would allow colorectal trainees to receive graded responsibility under direct mentorship and ensure patients get the best outcomes.
Concerns for patient safety and surgeon accountability are of the highest importance. The current literature suggests that robotic surgery can be performed safely and effectively if surgeons train properly. Although no standardized and validated program exists, surgeons must be educated on robotic technology and become familiar with its use in a laboratory setting before operating on patients. While in the early portion of the learning curve, operating in increments of graded responsibility or with a mentor ensures the highest chance of success. Like other authors, we believe that patients and surgeons alike would benefit from a formal credentialing process addressing both the preclinical and clinical aspects of robotic surgical training [22].
4.2 Patient Selection
When adopting a new technology, appropriate patient selection is as important as selecting the best surgeons (Table 4.2). While there are no specific indications for robotic colorectal surgery over traditional approaches, the best applications of this technology are those that leverage the advantages that robotics has over laparoscopic or open surgery. These advantages include superior three-dimensional viewing, stabilization of instruments and camera, improved surgeon ergonomics, and mechanical advantages including instruments with 7 degrees of freedom and 90 degrees of articulation [23].
Sex | Male |
Body habitus | Obese |
Preoperative radiotherapy | Yes |
Pathology | Malignancy |
Tumor location | Lower two thirds of the rectum |
4.2.1 Robotic Colon Surgery
While the first robotic-assisted colectomy was reported in the literature in 2002, there are no consensus guidelines for indications for robotic colon resection that do not apply to the open or laparoscopic techniques [24]. Indications previously described in the literature for robotic colectomy include colonic adenoma, polyps, carcinoid, and diverticulitis [14]. Reported robotic resections include left, right, and subtotal colectomies. Operative techniques included both intracorporeal and extracorporeal, stapled, and robotic-assisted hand-sewn anastomoses [25]. While multiple studies have demonstrated robotic colectomy to be safe and feasible for both benign and malignant disease, none have demonstrated any objective benefit to justify the increased cost or increased operative time associated with robotics [8, 25, 26].
One reason for the lack of improvement with robotic colectomy may be that the advantages of robotics cannot be fully utilized for this operation. The advantages of robotic surgery apply best to operating in confined spaces, whereas colonic resection requires dissection in multiple abdominal quadrants and it can be difficult to retract the redundant colon in order to provide adequate countertraction [26]. However, some authors do report advantages with splenic flexure takedown and dissection of the inferior mesenteric vessels [26]. In addition, creation of an intracorporeal hand-sewn anastomosis is easier, allowing placement of the minilaparotomy extraction incision in the most convenient site for the patient [27].
Additional considerations in patient selection are the effects of prolonged anesthesia and pneumoperitoneum due to increased operative times. While the specific physiological effects of pneumoperitoneum will be discussed in the next section, comorbidities including severe chronic obstructive pulmonary disease (COPD), sepsis, chronic renal insufficiency, and heart failure must be taken into account when selecting patients for robotic surgery.
4.2.2 Robotic Rectal Surgery
In contrast to colon surgery, robotic-assisted rectal surgery may provide distinct improvements over open and laparoscopic approaches. While standard laparoscopy is widely accepted for colonic resections, it still faces significant limitations in rectal cancer, particularly in those requiring a complete TME [28]. The advantage of laparoscopy is that it provides unobstructed views of the rectal tissue planes and allows a more precise dissection due to the magnified view, and the pneumoperitoneum assists in opening tissue planes in the mesorectal dissection [29].
However, due to the confined space of the pelvis, fixed instrument tips with limited dexterity, and poor surgeon ergonomics, the distal dissection is technically challenging [29]. It often results in clashing of instruments and a crowded operative field, restricting view and requiring the involvement of an experienced assistant. The use of electrocautery introduces smoke into the surgical field, further disrupting visualization. In addition, localization of the exact distal margin of the tumor, particularly when in the low rectum, can be challenging without direct tactile sensation. Finally, limited maneuverability and articulation of staplers often lead to multiple angulated staple lines, increasing the risk of anastomotic leak [29]. Each of these factors contributes to the high learning curve for laparoscopic rectal procedures described above.
RAS may provide solutions to many of these problems. First, because the surgeon is the camera operator and the three-dimensional view is stabilized, visualization and depth perception are improved [28]. Second, the robotic endowrists allow for improved dexterity, decreasing the difficulty of intracorporeal suturing as well as giving the surgeon the ability to approach the mesorectum from multiple angles. Third, robotic suturing may allow surgeons to create a single-stapled, double-purse-string anastomosis that could potentially reduce leak rates [30]. Finally, robotics allows for improved ergonomics, allowing the surgeon to sit, and decreases the awkward hand and arm positioning encountered in laparoscopic rectal resections.
4.3 Physiology of Pneumoperitoneum
Similar to laparoscopy, intra-abdominal robotic procedures require the establishment of pneumoperitoneum, and special consideration of the physiological effects of sustained pneumoperitoneum must be considered. Particularly due to the learning curve and increased operative times, these physiological effects may play an even larger role with RAS than they do with laparoscopy. An understanding of this topic plays an important role in patient selection and management. These physiological effects will be discussed in a system-based manner (Table 4.3).
Table 4.3
Organ-specific physiological effects of pneumoperitoneum
Organ system | Mechanical effect | Biochemical effect |
|---|---|---|
Pulmonary | ↑ Functional residual capacity | ↑ End-tidal CO2 |
↑ Dead space | ||
↑ Atelectasis | ||
Cardiovascular | ↓ Venous return | Metabolic acidosis |
↓ Cardiac output | ||
Renal | ↓ Renal perfusion | ↑ Renin |
↑ Antidiuretic hormone | ||
↑ Aldosterone |
Pneumoperitoneum is typically created with the insufflation of carbon dioxide (CO2) gas. CO2 is noncombustible, rapidly soluble in the blood, and relatively inexpensive [31]. There is no single ideal pressure to achieve pneumoperitoneum. Rather, the lowest intra-abdominal pressure that allows adequate exposure of the operative field should be used [32].
4.3.1 Pulmonary
When the peritoneal cavity is insufflated with CO2 gas, a small portion is absorbed in the blood, but the majority combines with water in red blood cells to form carbonic acid and dissociates into hydrogen and bicarbonate [33]. CO2 absorbed through the peritoneum is metabolized in a similar fashion.
This leads to an increase in end-tidal CO2 as high as 50 % requiring an increase in minute ventilation to achieve eucapnia [33]. Regardless of whether or not the patient achieves this, most healthy patients can easily adapt using intracellular and plasma buffering systems. However, patients with diminished buffering capacity such as those with severe COPD or sepsis may be unable to tolerate the increased CO2 load, resulting in acidosis and its sequelae.
In addition to the biochemical effects of CO2, increased intra-abdominal pressure disrupts typical pulmonary mechanics [33]. Diaphragmatic movement is impaired resulting in a decreased functional residual capacity and increased dead space. Controlled ventilation with large tidal volumes can offset pulmonary problems by decreasing atelectasis. This can also be offset by increased positive end-expiratory pressure (PEEP); however, this must be balanced with the resulting cardiovascular effects, which will be described next. However, despite these changes, studies have demonstrated that laparoscopy results in smaller postoperative changes in pulmonary function tests compared to open surgery [33]. Overall, in healthy patients, changes to pulmonary mechanics are of minimal clinical significance.
Due to the resulting hypercapnia and respiratory acidosis, the monitoring of end-tidal CO2 is mandatory during laparoscopy, whether traditional or robotic assisted. In patients with limited pulmonary reserves, capnoperitoneum carries an increased risk of CO2 retention, increasing the difficulty of extubation. In patients with severe cardiopulmonary disease, arterial blood gas monitoring and continuous capnography are recommended [34].
4.3.2 Cardiovascular
The primary changes to the cardiovascular system due to CO2 insufflation also result from hypercarbia and mechanical compression. These physiological effects occur most often during the early stages of insufflation [34].
The increase in end-tidal CO2 may result in a mild hypercapnia (pCO2 45–50 mmHg), which has little effect on hemodynamics. However, severe hypercapnia (pCO2 55–70 mmHg) and the resulting acidosis may result in hemodynamic changes. CO2 has a direct effect of myocardial depression and vasodilation [33]. These effects trigger a compensatory sympathetic reaction resulting in a reflex tachycardia and vasoconstriction.
However, the primary effect of pneumoperitoneum on the cardiovascular system is due to mechanical compression of the venous system which lowers venous return. This compression, seen with intra-abdominal pressures from 12 to 15 mmHg, results in a decreased cardiac preload and cardiac output and a corresponding increase in heart rate, mean arterial pressure, and systemic and pulmonary vascular resistance [34].
Changes in patient positioning are often essential to gain proper visualization of the operative field. However, these changes can also affect hemodynamics. Reverse Trendelenburg position intensifies the physiological effects of pneumoperitoneum, while Trendelenburg position increases venous return [34]. Additionally, the use of PEEP of 10 cm H2O during pneumoperitoneum to decrease atelectasis decreases preload and cardiac output [34].
It should be noted that the European Association of Endoscopic Surgery (EAES) in their 2001 clinical practice guidelines on pneumoperitoneum stated the effects of a 12–14 mmHg CO2 pneumoperitoneum are not clinically relevant in healthy patients (ASA I or II) [34]. However, special consideration must be given to patients with underlying cardiac disease or other significant morbidities. Invasive blood pressure or circulating volume status measurements should be considered, and all of these patients should receive adequate preoperative beta-blockade, volume loading, and pneumatic compression of the lower limbs [34].
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