Robotic Surgery for Benign and Cancerous Tumors of the Kidney
Partial nephrectomy is a procedure that removes a tumor from the kidney while sparing the remaining normal tissue. There is increasing evidence that doing so is important not only in patients with pre-existing renal insufficiency and/or medical comorbidities, but also healthy patients with normal kidney function. For these reasons partial nephrectomy has become the preferred treatment for renal masses that are amenable to this approach. This complex procedure, which was previously performed through a large open flank incision,is not universally done through a robotic approach (see nephrectomy incision comparison).
Advantages of Robotic Partial Nephrectomy
The robotic approach to partial nephrectomy offers the advantage of maximizing the surgeon’s dexterity so that tumor excision and renal reconstruction can be completed in a precise and rapid fashion. The time taken during this step of partial nephrectomy should be limited because the kidney’s blood supply (from the main renal artery) must be occluded temporarilyduring excision to prevent bleeding into the operative field. During occlusion of the blood supply the kidney is deprived of oxygen and therefore the tumor must be removed and the remaining healthy kidney reconstructed in an expeditious fashion. The robotic approach to partial nephrectomy extends the surgeon’s experience with laparoscopic partial nephrectomy, enabling more complex lesions to be removed with unmatched precision and speed.
How a Robotic Partial Nephrectomy is Performed
The surgery begins first by inflating the abdomen with carbon dioxide so that the 3-D high definition robotic camera can be used to visualize the internal structures of the abdomen through a 1 cm incision. The robotic working instruments are then inserted through the skin into the abdomen by placing special ports called trochars. Trochars are 8 mm instruments that have a valve mechanism to prevent the pressurized gas from escaping while permitting the passage of small instruments required to perform the surgery. At this point the robot is then “docked” whereby the robotic patient cart (see robot docking image) is brought to the patient’s bedside and the arms of the robot attached to the camera port and robotic trochars. The “robot” is motionless without the surgeon. Once docked, the surgeon takes full control of the camera and all robotic arms through a sophisticated surgeon console that is in the operating room (see surgeon console image). Inside the surgeon console the surgeon has the advantage of magnified 3-dimensional high-definition vision of the operative field (see inside console view). A bedside assistant is required for retraction, suction, and the passage of instruments and sutures into the abdomen.
Due to the location of the kidney in the retroperitoneum, the first steps involve exposure of the kidney by carefully reflecting the left or right colon. Following this the major blood vessels to the kidney are identified, exposed and isolated (the renal artery and vein). In some cases there are multiple arteries and/or veins which require meticulous dissection to delineate. Once the main renal vessels have been exposed these are then traced laterally into the kidney where they branch (bifurcate) into smaller vessels called segmentals.
Once this has been accomplished the line along which the tumor will be cut away must be planned and marked out. Intraoperative ultrasound is then performed by placing a special laparoscopic ultrasound probe into the abdomen directly on the kidney and tumor (see Figure Intraoperative Live Ultrasound). These lives images and then cross-referenced with the pre-operative axial imaging (your CT or MRI scan) to localize the tumor and plan the excision. Electrocautery is then used to trace out the planned excision line on the surface of the kidney (see Cauterized Line of Excision)
Often during partial nephrectomy only one segmental renal artery may be clamped, one which provides all the blood supply to the portion of the kidney where the tumor resides. This is confirmed by utilizing cutting edge technology from Intuitive Surgical called intravascular fluorescence imaging. A fluorescent dye (IC Green) is injected into the IV by anesthesia. An advanced robotic camera and lens are then activated to detect the fluorescent dye which is quickly visualized as a green glow in the perfused portions of the kidney and surrounding organs. The tumor and nearby normal kidney tissue is dark indicating excellent vascular control due to clamping of the segmental renal artery that delivers blood to this area (see image of fluorescence imaging).
After the necessary artery is clamped the tumor is then cut out of the kidney with robotic scissors and placed in a laparoscopic specimen bag. The defect in the kidney is then carefully sutured to close the urinary collecting system (if entered) and control all major renal blood vessels. The occlusive vessel clamp is then removed and blood is allowed to flow back into the kidney so that it can “breath” and resume its function (see partial nephrectomy specimen).
Tumors that are located on the back side of the kidney can be approached through the standard transperitoneal approach described above or through a retroperitoneal approach. In the retroperitoneal approach to partial nephrectomy the pressurized carbon dioxide is used to create a potential space behind the kidney by expanding the retroperitoneum. This allows the surgeon to perform the entire procedure without entering the patient’s abdominal cavity. This reduces the risk of injury to adjacent organs and minimizes the surgical side effects on the intestinal tract, further speeding recovery.
Retroperitoneoscopic partial nephrectomy begins by creating a small space in the retroperitoneum below and behind the kidney near the tip of the last, or 12th, rib. A special balloon is then used to expand the space behind the kidney so that the robotic camera port can be inserted. Once the robotic trochars are placed, the dissection proceeds rapidly to expose the major vessels of the kidney (the renal artery and vein) without needing to move the colon, liver or spleen. The tumor excision is performed in precisely the same manner as that described for the transperitoneal approach. Whether you are a candidate for robotic retroperitoneal partial nephrectomy depends upon your tumor location and other factors. Dr. Berkman will discuss these surgical approaches with you.