Dr. Goh then gave a brief overview of the various robotic systems manufactured by Intuitive Surgical Inc. and utilized by most centers in the world. He began with the SI robot, which is a 4-arm system with an analog camera (10 mm) and is cart based. Its joints require arms spacing, and it is aimed specifically at smaller target workspace with 5 and 8 mm instruments (Figure 1).
Figure 1 – SI Robot:
The Xi is a newer model which is also a 4-armed system with a digital camera (8 mm) and is boom based. It entails tighter spacing for the arms with smaller joints and has a multi-quadrant workspace. The instruments are 8 mm, and they have increased flexibility with port placement. There are fewer collisions with it and increased patient clearance. Its biggest advantage is that the base can be placed anywhere (figure 2).
Figure 2- Xi Robot:
Additional robots include the X robot (Figure 3), which is a 4-arm system which is less expensive. The port interface and camera are like that of the Xi. It has a longer reach and narrower working profile than the Si. It does not have multi-quadrant support and no table motion support. Lastly, the most recent robot is the new single port system, with the significant advantage of working through a single port (Figure 4).
Figure 3 – X Robot:
Figure 4 – Single Port Robot:
The Xi robot is advantageous in surgeries involving the kidney, including:
-Nephroureterectomy
-Retroperitoneoscopic surgery (partial and radical nephrectomy)
-Horseshoe kidney surgery
-IVC thrombectomy
It also has advantages in specific patient factors, including BMI>50, small torso, and prior abdominal surgery.
While the Si robot works in a triangle, the Xi robot works on a straight line and can work more laterally (Figure 5).
Figure 5 – Si Robot vs XI Robot:
The Si requires placement of the patient in low lithotomy so that it can be placed in between the patient’s legs. The arms need to be tucked, Allen stirrups need to be used, with padding of all required joints and the chest needs to be strapped. The Si is mainly used for prostatectomy, cystectomy and distal ureteral reimplantation. The Si requires the use of a blue pad underneath the patient, to prevent sliding during Trendelenburg, and a foam chest strap.
However, the Xi robot can work when the patient is in a supine position, and also requires elbow pads and strapping of the chest. It can be used for prostatectomy, cystectomy, distal ureteral reimplantation, and retroperitoneal lymph node dissection.
Dr. Goh continued and described the various positions for the relevant urologic robotic procedures. The modified lateral position (Figure 6) is appropriate for partial nephrectomy, adrenalectomy, pyeloplasty, and proximal ureteral reconstruction. The patient is positioned over the break of the table with some flexion, with no axillary roll, and arms together, and he/she is padded with pillows.
Figure 6 – Modified Lateral Position:
The modified thoracoabdominal position is indicated for single dock nephroureterectomy, and mid to proximal ureteral reconstruction. Pillows are used under the knees, and the pelvis is relatively flat, with arms padded. Lastly, the full flank position, where the patient is with his back at 90 degrees and flushed to the edge of the bed is indicated for retroperitoneal procedures, including partial nephrectomy, adrenalectomy, and pyeloplasty.
Dr. Goh moved on to discuss the important topic of compartment syndrome that can occur in surgeries. It is defined by pain out of proportion to the exam and firm muscle group. If it occurs, the patient should be examined by vascular and/or orthopedic physicians. The known risk factors include prolonged cases (over four hours), early learning curve (<20 cases), high BMI (>30), and peripheral vascular disease. Most patients require fasciotomy as treatment. Prevention is key and includes: being alert for any patients with BMI >30 at surgery timeout, making sure to reposition the patient after 4 hours of operation and check the patient’s extremities every four hours.
Other important issues to consider during robotic surgery are peripheral neuropathy and rhabdomyolysis. Peripheral neuropathy can occur in the upper extremity involving the ulnar, median, axilla, and brachial plexus. It can also manifest with ischemic optic neuropathy after extended Trendelenburg position. Lower extremity with the involvement of the peroneal, femoral, obturator nerves can also occur. Rhabdomyolysis, occurring because of compression and ischemia, can occur in lithotomy or flank position. It is critical to recognize it early and treat with hydration and alkalinization. It is associated with increased risk for other complications (5x), mortality (4x), and increased the length of stay (2x).1
It is also important to mention the associated anesthesia complications, including airway consideration in morbidly obese patients, and those with COPD. Additionally, steep Trendelenburg and insufflation are associated with increased airway resistance, leading to upper airway edema, and reduction of pulmonary compliance. It is therefore important to check tidal volumes and make sure peak pressure is less than 40, with end-tidal CO2 of 35-55. If required, certain adjustments can be made, including reduction of pneumoperitoneum to 8 mm, minimalization of Trendelenburg, administration of bronchodilators and usage of goal-directed fluid therapy.
Dr. Goh summarized his talk with these take-home messages:
- Setup is key to success
- Proper patient positioning can facilitate access and optimize the procedure.
- Positional awareness is critical to minimize complications
- Active communication with anesthesia is important particularly in patients with pulmonary compromise.
Presented by: Alvin Goh, MD, Memorial Sloan Kettering Cancer Center
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at 2019 3rd Annual North American Robotic Urology Symposium (NARUS), February 8-9, 2018 - Las Vegas, Nevada, United States
References:
1. Gelpi et al. J Urol 2016