Partial Nephrectomy in Central Renal Tumors

JOURNAL OF ENDOUROLOGY Volume 32, Supplement 1, May 2018 ª Mary Ann Liebert, Inc. Pp. S-63–S-67 DOI: 10.1089/end.2018.0046

Partial Nephrectomy in Central Renal Tumors Sohrab Arora, MCh and Craig Rogers, MD

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Abstract

Nephron-sparing surgery, especially through a minimally invasive approach, is increasingly being performed for incidentally detected renal masses with excellent outcomes. Tumors in central location remain a surgical challenge during nephron-sparing surgery. In this chapter, we discuss the minimally invasive management of these tumors, which include complex hilar tumors and endophytic central tumors, with a focus on surgical technique. The key to management of these tumors is to maintain good preoperative hydration, achieving adequate exposure of tumor, and the use of intraoperative ultrasound to plan the resection plane. Individual vessels may be ligated as they enter close to the tumor. Careful renorrhaphy is essential, especially in hilar tumors, which have major blood vessels at the base of the tumor. Selective use of near infrared fluorescence imaging, on-demand ischemia, early unclamping, enucleoresection techniques, and intracorporeal hypothermia may help minimize, or reduce the effect of warm ischemia. Keywords: partial nephrectomy, central renal tumors, cancer, kidney cancer, nephron-sparing surgery

Introduction

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here has been a steady increase in the incidence of renal cell cancer in the United States over the last few decades. From 7 cases per 100,000 population per year in 1975, the incidence has more than doubled to 15.3 cases per 100,000 in 2013.1 At the same time, there has been a steady decrease in the average size of tumors at presentation.2 This phenomenon can be attributed to increased incidental detection of renal tumors by noninvasive imaging modalities. There has also been a trend toward using nephron-sparing surgery,3 and minimally invasive approaches4 in the management of these tumors. Although in the presence of normal contralateral kidney, the advantage of partial nephrectomy (PN) over radical nephrectomy (RN) on overall survival benefit is debated,5,6 it has been shown to be associated with a decreased risk of chronic kidney disease (CKD),7 and decreased cardiovascular morbidity.8 Minimally invasive approaches have been shown to be effective, and are increasingly being used for complex renal tumors,9 and solitary kidneys,10 with equivalent outcomes in endophytic, mesophytic, and exophytic tumors,11 with low rate of conversion to RN.12 In this chapter, the authors discuss the management of central tumors, which include complex hilar tumors, and endophytic central tumors, with a focus on surgical technique. Indications

Absolute indications for PN include circumstances where RN would make the patient dependent on renal replacement therapy. This includes tumors in functional or anatomical

solitary kidneys, impairment of contralateral or global renal function, or a medical condition, such as diabetes mellitus, hypertension, or renal artery stenosis, which could impair the renal function in the future, and bilateral renal tumors. Age of the patient at the time of the presentation is also an important consideration. Elective indications for PN include small, localized renal tumors, with a normal contralateral kidney. With the increasing use of nephron-sparing surgery, PN has become the standard of care for clinical T1a, and a preferred treatment for clinical T1b tumors. With improvements in axial imaging, intraoperative ultrasound, real-time fluorescence imaging, and overall increasing expertise in robotic surgery, PN is being done increasingly. This includes larger tumors, tumors with high nephrometry scores,13 multiple tumors,14 tumors in solitary kidneys,15 or in patients with significant CKD, completely endophytic tumors,16 and tumors in a central location. While PN is increasingly being done in these tumors, they remain a surgical challenge. Preoperative Preparation

The preoperative preparation for robot-assisted PN in central tumors is similar to preparation for PN in other renal tumors. Consent should include the possibility of RN or open conversion. Platelet inhibitors, such as aspirin or clopidogrel are generally stopped 5 to 7 days before surgery. Blood type and screen is done before surgery in expectation of

Vattikuti Urology Institute, Henry Ford Hospital, Detroit, Michigan.

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intraoperative blood loss. Adequate hydration to maintain good renal perfusion may be beneficial. Our protocol is to start a crystalloid infusion in the preoperative area with a goal of 2 to 3 L total infusion before hilar clamping. It is helpful to follow a checklist of the equipment and material needed in the operative room. This includes bulldog and Satinski vessel clamps, an open tray for a possible open partial or RN. Hemostatic agents, vascular staplers, and ultrasound probes should also be available. After induction of general anesthesia, a Foley catheter is placed.


Patient Positioning, Port Placement, and Docking of the Robot

The patient is placed in a modified flank position with the ipsilateral side up. All pressure points are adequately padded. A mild flexion of table increases the working space and minimizes clashing of robotic arms. The patient is adequately secured to the table. Pneumoperitoneum is created with a Veress needle. Insufflation may be done to 20 mm Hg until the placement of the first port and subsequently reduced to 12 to 15 mm Hg through the surgery. Port placement is done to ensure optimal access to the tumor and renal hilum. A port template for S/Si and Xi systems is shown in Figure 1a. The camera port is placed at the lateral edge of the rectus muscle cephalad to the umbilicus. For obese patients, ports may be shifted even more lateral and cephalad. A robotic port is placed 1 cm below the subcostal margin lateral to the rectus abdominis. For the da Vinci Xi system, all the four ports may be placed in a straight line (Fig. 1b). It should be ensured that the ports are at least 6 to 8 cm away from each other to avoid clashing of robotic instruments. An assistant port is placed in the midline between the cephalad robotic port and the camera port. An additional port may be placed for improved access to introduce a Satinsky clamp for ‘‘en-bloc’’ clamping of the renal hilum if required. For right-sided tumors, a 5-mm port may be placed just below the xiphisternum for a locking grasper to retract the liver. A fourth arm may be helpful in complex tumors, as it provides additional surgeon autonomy. The Robot is docked over the ipsilateral shoulder using the S/Si systems and may be docked straight over the back with the Xi system. Surgical Steps Bowel mobilization

Adequate exposure is essential while attempting PN for central tumors. A combination of wide mobilization of the

FIG. 1. Port placement. (a) For the da Vinci Si and the S systems. A three-arm configuration is shown. A fourth arm may be added lateral and caudal to the third arm. (b) For the Xi system. A fourarm configuration is shown.

ARORA AND ROGERS

bowel and the kidney, use of the fourth robotic arm, extra assistant ports, or the use of lap sponges may help achieve this goal. The dissection begins with reflection of colon along the line of Toldt. The fourth arm can be used at this stage to pull the Gerota’s fascia anteriorly. This, coupled with countertraction of the bowel by the assistant helps in bowel mobilization, especially in obese patients with abundant perinephric fat. Hilar dissection

Once the ureter is seen, a plane is developed between the ureter–gonadal complex and the psoas fascia. The fourth arm may be placed under the ureter, to place the renal hilum under a stretch, and free both the arms of the surgeon for hilar dissection. It may be helpful to mobilize the upper pole of the kidney to facilitate exposure of the hilum. The hilar vessels may be skeletonized enough for the application of robotic bulldog clamps on the vessels at a subsequent step. Tumor exposure and marking

The Gerota’s fascia and perinephric fat is dissected for adequate exposure of the tumor. The kidney is freed from its lateral attachments, and a laparoscopic sponge may be placed behind the kidney to stabilize it, and keep it in place. If possible, the tumor exposure and mobilization of the kidney should be such that the tumor is directly facing the surgeon. A flexible drop-in ultrasound probe may be introduced through the primary assistant port. The ultrasound probe is connected to the da Vinci system, allowing the ultrasound view to be displayed on the console screen using the TilePro system. Held by the fourth robotic arm, the probe is used to define tumor margins and limits of resection. Resection margin may be scored circumferentially on the renal capsule using monopolar cautery. This prepares the stage for clamping of renal vessels. At this point, it may be useful to run a preclamp checklist, where all sutures, hemostatic agents, endoGIA staplers, bulldog and Satinski clamps, Indocyanine green (ICG), and adequate CO2 for insufflation are visually confirmed. The anesthesiologist may infuse mannitol at this time to maintain adequate renal perfusion. Clamping and excision of the tumor

Robotic bulldog clamps are placed on the renal vessels by the surgeon or a skilled bedside assistant through the assistant ports.

PARTIAL NEPHRECTOMY IN CENTRAL RENAL TUMORS


For completely endophytic central tumors. These tumors are a surgical challenge, as they carry a higher risk of pelvicaliceal system involvement, and if large and endophytic, also carry a higher risk of renal vessel injury, as the tumor may reach to the sinus fat. It may be useful to widen the resection margin farther away from the tumor in these cases, so the resection can proceed in a shallow plane around the tumor. Preoperative imaging and intraoperative ultrasound are essential to define the limits of resection in these cases. For hilar tumors. The scoring of the tumor in these cases is done in an inverted U-shaped fashion, with hilum at the open end of the ‘‘U.’’ After clamping, the sinus fat plane is entered (see Supplementary Video S1; Supplementary Data are available online at www.liebertpub.com/end). Individual vessels may be ligated as they enter the tumor. FireFly (discussed later) may help define tumor margins. If the tumor capsule is seen at any point, the resection plane can be corrected away from the tumor accordingly. Pelvicaliceal system on either side of the tumor, if opened up, may be a useful guide, as it forms a safe and easily identifiable plane of resection. For hilar tumors abutting critical structures, tumor enucleoresection techniques described elsewhere17,18 may be required to preserve these structures. A cleavage plane is developed between the radially oriented renal pyramids and parenchyma by atraumatic blunt separation. This plane is often described as a ‘‘pseudocapsule’’ around the tumor and consists of inflammatory and sclerotic tissue. Enucleation also helps preserve maximal normal renal tissue. Renorrhaphy

Careful renorrhaphy is essential, especially in hilar tumors, which have major blood vessels at the base of the tumor. Aggressive, or deep closure of the tumor defect may compress, or injure these vessels. Thus, deep sutures through the floor of the defect are avoided. One of the methods of closing the defect may be by doing a superficial renorrhaphy with a bolster at the base. Another method described is the ‘‘V-hilar suture renorrhaphy’’ by Kaouk and colleagues.19 This uses inner layer sutures to reshape the parenchymal defect, followed by continuous horizontal mattress suture to approximate the renal capsule (see Supplementary Video S2).

S-65 Early unclamping

The renal vessels are unclamped after the inner renorrhaphy with a running suture. The outer renorrhaphy is performed offclamp.25 Hemostatic agents and additional sutures may be used in case of ongoing bleeding. It has been demonstrated that despite larger (mean 3.6 cm vs 3.2 cm) and more complex tumors (mean RENAL score 6.9 vs 6.1), patients undergoing early unclamping had shorter warm ischemia time (WIT) (16.7 minutes vs 22.3 minutes), higher blood loss (369.5 mL vs 240 mL), and no statistically significant difference in transfusion rates.26 Similar reductions in WIT were noted by other groups (from 31.1 to 13.9 minutes27 and 28 to 18.5 minutes28). Selective and ‘‘super’’-selective clamping

In this technique, hilar dissection is continued until multiple segmental renal vessels are exposed, and only the vessel(s) that feed the tumor are clamped.29,30 Various means can be used to confirm the region of ischemia, including visual inspection, intraoperative Doppler, or near-infrared fluorescence imaging with ICG dye (IC-Green; Akorn, Lake Forest, IL).31 ICG is a water-soluble dye, which is injected intravenously at a dose of 5 to 10 mg following selective clamping. It binds to albumin and therefore remains primarily in the circulation. When viewed under near-infrared light (700–1000 nm), ICG fluoresces bright green (FireFly). This makes the well-perfused renal parenchyma look bright green, whereas the ischemic tissue and tumor look dark. Selective clamping may be most amenable to hilar tumors or polar tumors in which the feeding vessels are more easily defined. Further refinement of this approach led to the development of anatomical ‘‘zero-ischemia’’ concept by Gill et al., where super-selective clamping of the tumor-specific tertiary or higher-order arterial branches is done.32,33 Off-clamp techniques require good preoperative imaging such as a three-dimensional CT scan. The technique is associated with increased blood loss and increased surgical complexity, both for the console surgeon and the bedside assistant. The data on ‘‘zero-ischemia’’ and super-selective techniques are currently limited to a few centers. The longterm renal functional benefits and reproducibility of these approaches has yet to be demonstrated.

Minimizing Ischemia Time

It is essential to minimize ischemia time, especially in patients with existing renal compromise,20 or with a solitary kidney,21 or multiple tumors. Various factors determine postoperative renal function in patients undergoing PN. Although there is no consensus on the ideal ischemia time limit,22,23 warm ischemia is a potentially modifiable surgeonspecific parameter.23 Various strategies to reduce ischemia time are as follows: On-demand ischemia

Tumor excision is started without clamping, and the pedicle is clamped only when there is inability to proceed due to bleeding obscuring the surgical field.24 This reduces the total ischemia time. This technique has been described for smaller tumors, but may be useful even for larger tumors.

Intracorporeal (regional) hypothermia

This technique has been used, in an effort to alter the oxygen demand–supply ratio of the renal tissue.34–37 Lane et al. showed that patients with median WIT of 22 minutes had comparable decline in glomerular filtration rate 3 months after surgery to those with cold ischemia time of 45 minutes, suggesting the potential mitigating impact of the latter technique in patient with complex tumors and longer durations of expected WIT.23 At our center, we evolved a technique for intracorporeal cooling and extraction: following hilar clamping, ice slush is introduced through the GelPoint (through modified syringes with their front end cutoff, rigid sigmoidoscopies, or dedicated ice plungers) and applied over the kidney surface. The mean cold ischemia time in this series was 19.6 minutes. They allowed kidney surface temperature to fall to