Ramakrishna Venkatesh

Renal hypothermia achieved by retrograde endoscopic cold saline perfusion: technique and initial clinical application

We describe the technique and initial clinical results with application of a novel method to achieve renal parenchymal hypothermia using retrograde ureteral access. A 38-year-old man was scheduled to undergo an open right partial nephrectomy for renal cell carcinoma. Before the open procedure, a ureteral access sheath was advanced to the ureteropelvic junction under fluoroscopic guidance; through the access sheath, a 7.1F pigtail catheter was also advanced. After clamping the renal artery and vein, ice-cold saline (-1.7 degrees C) was circulated through the access sheath and drained via the 7.1F pigtail catheter; renal cortical and medullary parenchymal temperatures were measured using thermocouples. This technique of intrarenal cooling achieved a renal cortical temperature of 24 degrees C and a medullary temperature of 21 degrees C. The endoscopic procedure required an additional 35 minutes of operation time to complete. Histopathologic investigation of the specimen revealed no associated damage to the ureteral urothelium from access sheath placement or to the collecting system urothelium from exposure to ice-cold saline irrigation. Retrograde endoscopic renal hypothermia is feasible and effective. The technique requires no novel equipment or special surgical skills. This method can be applied to patients undergoing open or laparoscopic complex renal ablative and reconstructive procedures that require renal hypothermia.

Durability of Flexible Ureteroscopes: A Randomized, Prospective Study

PURPOSE We performed a randomized, prospective, multi-institutional study evaluating the durability of commercially available flexible ureteroscopes. MATERIALS AND METHODS A total of 192 patients were randomized to the use of 7 less than 9Fr flexible ureteroscopes, including the Storz 11274AA and Flex-X, the ACMI DUR-8 and DUR-8 Elite, Wolf models 7330.170 and 7325.172, and the Olympus URF-P3. Information about total and lower pole use time, the number and method of ureteroscope insertion, and they type and duration of accessory instrumentation was recorded. Surgeons were asked to rate the visibility and maneuverability of the instrument on a scale of 0-poor to 10-excellent. RESULTS The indication for ureteroscopy was upper tract calculi in 87% of cases. Of ureteroscope insertions 97% were performed through an access sheath. The average of number of cases before repair ranged from 3.25 for the Wolf 7325 to 14.4 for the ACMI DUR-8 Elite. Average ureteroscope operative time was statistically longer for the DUR-8 Elite (494 minutes) than for the Flex-X (p = 0.047), and the Wolf 7325 and 7330 (p = 0.001 and 0.001, respectively). Duration of use before repair for the URF-P3 (373 minutes) was statistically longer than for the Wolf 7325 and 7330 (p = 0.016 and 0.017, respectively). Minutes of use with an instrument in the working channel were significantly more with the DUR-8 Elite and the URF-P3 than the Wolf 7330 (p = 0.017 and 0.008) and 7325 (p = 0.012 and 0.005, respectively). The ureteroscope that experienced the greatest average duration of lower pole use was the URF-P3, while the shortest was the Wolf 7325 (103 vs 20 minutes, p = 0.005). Average minutes of laser use before breakage was significantly longer for the DUR-8 Elite than for the Wolf 7325 (110 vs 21 minutes, p = 0.021) and 7330 (24 minutes, p = 0.025). CONCLUSIONS Currently available less than 9Fr flexible ureteroscopes remain fragile instruments. The DUR-8 Elite and Olympus URF-P3 proved to be the most durable devices.

Needle-based ablation of renal parenchyma using microwave, cryoablation, impedance- and temperature-based monopolar and bipolar radiofrequency, and liquid and gel chemoablation: Laboratory studies and review of the literature

BACKGROUND AND PURPOSE Small renal tumors are often serendipitously detected during the screening of patients for renal or other disease entities. Rather than perform a radical or partial nephrectomy for these diminutive lesions, several centers have begun to explore a variety of ablative energy sources that could be applied directly via a percutaneously placed needle-like probe. To evaluate the utility of such treatment for small renal tumors/masses, we compared the feasibility, regularity (consistency in size and shape), and reproducibility of necrosis produced in normal porcine kidneys by different modes of tissue ablation: microwaves, cold impedance-based and temperature-based radiofrequency (RF) energy (monopolar and bipolar), and chemical. Chemoablation was accomplished using ethanol gel, hypertonic saline gel, and acetic acid gel either alone or with simultaneous application of monopolar or bipolar RF energy. MATERIALS AND METHODS A total of 107 renal lesions were created laparoscopically in 33 domestic pigs. Microwave thermoablation (N=12) was done using a Targis T3 (Urologix) 10F antenna. Cryoablation (N=16) was done using a single 1.5-mm probe or three 17F microprobes (17F SeedNet system; Galil Medical) (N=10 single probe and N=6 three probes); a double freeze cycle with a passive thaw was employed under ultrasound guidance. Dry RF lesions were created using custom-made 18-gauge single-needle monopolar probe with two or three exposed metal tips (GelTx) (N=12) or a single-needle bipolar probe (N=6) at 50 W of 510 kHz RF energy for 5 minutes. In addition, a multitine RF probe (RITA Medical Systems) was used in one set of studies (N=6). Both impedance- and temperature-based RF were evaluated. Chemoablation was performed with 95% ethanol (4 mL), 24% hypertonic saline (4 mL), and 50% acetic acid (4 mL) as single injections. In addition, chemoablation was tested with monopolar and bipolar RF (wet RF). Tissues were harvested 1 week after ablation for light microscopy. RESULTS In 11 of the 15 ablation techniques, there was complete necrosis in all lesions; however, three ethanol gel lesions had skip areas, three hypertonic saline gel lesions showed no necrosis or injury, and one monopolar RF and one bipolar RF lesion showed skip areas. In contrast to impedance-based RF, heat-based RF (RITA) caused complete necrosis without skip areas. All cryolesions resulted in complete tissue necrosis, and cryotherapy was the only modality for which lesion size could be effectively monitored using ultrasound imaging. CONCLUSIONS Cryoablation and thermotherapy produce well-delineated, completely necrotic renal lesions. The single-probe monopolar and bipolar RF produce limited areas of tissue necrosis; however, both are enhanced by using hypertonic saline, acetic acid, or ethanol gel. Hypertonic saline gel with RF consistently provided the largest lesions. Ethanol and hypertonic saline gels tested alone failed to produce consistent cellular necrosis at 1 week. In contrast, RITA using the Starburst XL probe produced consistent necrosis, while impedance-based RF left skip areas of viable tissue. Renal cryotherapy under ultrasound surveillance produced hypoechoic lesions, which could be reasonably monitored, while all other modalities yielded hyperechoic lesions the margins of which could not be properly monitored with ultrasound imaging.

Association of Tumor Size, Location, R.E.N.A.L., PADUA and Centrality Index Score with Perioperative Outcomes and Postoperative Renal Function

PURPOSE Multiple scoring systems have been proposed to standardize the description of anatomical features of renal tumors. However, it remains unclear which of these systems, if any, is most useful, or whether any performs better than simply reporting tumor size or location in patients undergoing partial nephrectomy. To clarify these issues we evaluated the association of tumor size, location, R.E.N.A.L. (Radius/Exophytic/Nearness to collecting system/Anterior/Location), PADUA (Preoperative Aspects and Dimensions Used for an Anatomical classification) and centrality index scores with perioperative outcomes. MATERIALS AND METHODS Patients undergoing partial nephrectomy with available preoperative imaging were identified from 2005 to 2011. R.E.N.A.L., PADUA and centrality index scores were assigned according to the described protocols for those systems. Associations between each variable and ischemia time, estimated blood loss, total operative time and change in estimated glomerular filtration rate were examined. RESULTS A total of 162 patients were identified with a median tumor size of 3.1 cm (IQR 2.2 to 4.6). Median estimated blood loss, ischemia time and total operative time were 200 ml (IQR 100 to 300), 24 minutes (IQR 20 to 30) and 211 minutes (IQR 179 to 249), respectively. Each scoring system was found to have a statistically significant (p <0.001) correlation with ischemia time, with the centrality index system showing the strongest correlation. Furthermore, each of the scoring systems showed a stronger correlation with ischemia time than tumor size or tumor location. CONCLUSIONS Each scoring system outperformed tumor size and location, and may be useful when describing the surgical complexity of renal tumors treated with partial nephrectomy.

Combined Percutaneous And Retrograde Approach To Staghorn Calculi With Application Of The Ureteral Access Sheath To Facilitate Percutaneous Nephrolithotomy

PURPOSE We describe our technique and clinical experience with application of the ureteral access sheath for single access ablation of staghorn and partial staghorn calculi. MATERIALS AND METHODS We retrospectively reviewed our experience with 9 patients who underwent percutaneous nephrolithotomy for staghorn (6) or partial staghorn (3) renal calculi using a combined antegrade and retrograde approach. Patient data, operative parameters, efficacy of stone ablation and convalescence parameters were reviewed. RESULTS Mean operative time for the primary procedure was 3.1 hours with a mean estimated blood loss of 290 ml. Postoperatively, the mean analgesic requirement was 33.2 mg. MSO(4) equivalents. Hospital stay was 3.2 days. There were no major and 4 minor (44%) complications. No patient required transfusion. Complete stone clearance was achieved in 7 of the 9 cases (78%) using a single percutaneous nephrostomy tract. CONCLUSIONS Our preliminary clinical experience using the ureteral access sheath during percutaneous nephrolithotomy for simultaneous antegrade and retrograde stone treatment has been favorable. A large renal stone burden can be successfully managed with a single percutaneous access and limited blood loss.

Hemostatic laparoscopic partial nephrectomy assisted by a water-cooled, high-density, monopolar device without renal vascular control

OBJECTIVES To evaluate the feasibility of laparoscopic partial nephrectomy assisted by a water-cooled, high-density, monopolar device (TissueLink Floating Ball). METHODS Transperitoneal laparoscopic partial nephrectomy was performed without vascular control for four renal tumors in 3 patients. A flexible ultrasound probe was used to confirm tumor location and depth. Gerotas fascia was opened distant from the tumor site. Renal fat was dissected from the renal parenchyma except for the fat overlying the tumor. The tumor resection area was marked 1 cm outside the boundaries of the tumor. After application of the TissueLink Floating Ball at the planned surgical margin, the tumor was resected with cold laparoscopic scissors. Bleeding from the vessels of the divided renal parenchyma was controlled with the Floating Ball if necessary. The specimen was sent for frozen section to confirm margin status. RESULTS Mean estimated blood loss per tumor was 275 mL. The dissection extended to the collecting system in 2 of 4 cases. In 1 patient, a minor postoperative urine leak resolved spontaneously. CONCLUSIONS Use of the TissueLink Floating Ball facilitated resection of small renal tumors without renal vascular control. Although further study is necessary, water-cooled, high-density monopolar energy may have a role in laparoscopic partial nephrectomy.

Selective versus nonselective arterial clamping during laparoscopic partial nephrectomy: impact upon renal function in the setting of a solitary kidney in a porcine model.

INTRODUCTION Laparoscopic partial nephrectomy has emerged as a standard of care for small renal masses. Nevertheless, there remains concern over the potential for irreversible insult to the kidney as a result of exposure to warm ischemia. We aim to investigate the utility of selective segmental arterial clamping as a means to reduce the potential for ischemic damage to a solitary kidney during laparoscopic partial nephrectomy utilizing a porcine model. MATERIALS AND METHODS A total of 20 domestic swine were randomized into four equal groups. Each subject underwent laparoscopic radical nephrectomy to create the condition of a solitary kidney. On the contralateral side, a laparoscopic lower pole partial nephrectomy was performed, employing either selective or nonselective vascular clamping for either 60 or 90 minutes. Postoperatively, clinical status and serial serum studies were closely monitored for 1 week. RESULTS There were no intraoperative complications. The 90-minute nonselective clamping produced devastating effects, resulting in rapid deterioration into florid renal failure within 72 hours. The 60-minute nonselective clamping group experienced modest but significant rises in both blood urea nitrogen and creatinine. Both 60- and 90-minute selective clamping groups performed well, with no significant rises in creatinine over a 7-day period, and no instances of renal failure. CONCLUSIONS Selective arterial clamping is a safe and feasible means of vascular control during laparoscopic partial nephrectomy. In the porcine model, selective clamping appears to improve functional outcomes during prolonged periods of warm ischemic insult. Prospective evaluation of the technique in humans is necessary to determine if selective arterial control confers long-term functional benefits in patients with limited renal reserve.

Longterm Changes in Creatinine Clearance after Laparoscopic Renal Surgery

BACKGROUND Controversy exists about the impact of ischemia on renal function. We evaluated the creatinine clearance of patients having undergone laparoscopic renal extirpative and ablative surgery. STUDY DESIGN The records of patients undergoing laparoscopic procedures for renal masses from February 2000 to March 2004 were examined. Creatinine clearance (CrCl) for each patient was determined using the Cockcroft-Gault equation and ideal body weight. We compared CrCl changes of patients undergoing laparoscopic partial nephrectomy (without renal ischemia [LPN-none], with warm ischemia [LPN-warm], and with cold ischemia [LPN-cold]) with patients undergoing laparoscopic radical nephrectomy (LRN) and laparoscopic cryoablation. Patients predisposed to medical renal disease were substratified and evaluated. RESULTS All patients who underwent LRN or LPN-warm sustained a significant drop in CrCl on the first postoperative day, compared with patients who had LPN without ischemia or cryoablation (p < 0.01). The CrCl decrease correlated directly with warm ischemia time. Six months postoperatively, CrCl changes were no longer significant. Patients with medical renal disease risk factors were more likely to sustain longterm (1 year postoperatively) renal damage if they had renal ischemia, trending toward statistical significance. CONCLUSIONS Ischemia causes acute renal damage, which is apparently reversible in patients without evidence of medical renal disease. Patients with known medical renal disease have substantial longterm changes in renal function associated with unilateral renal ischemia. Considering the insensitivity of creatinine-based renal function metrics, only eliminating ischemic time will realize the goal of maximal nephron preservation, particularly in patients with preexisting medical renal disease.

Comparison of intrarenal pressure and irrigant flow during percutaneous nephroscopy with an indwelling ureteral catheter, ureteral occlusion balloon, and ureteral access sheath.

OBJECTIVES To determine the differential effects on renal pressures and irrigation flow associated with the application of different ureteral catheters during percutaneous nephrolithotomy. METHODS Using ex vivo fresh cadaveric tissue, we established a percutaneous nephrolithotomy model. After obtaining lower pole percutaneous access, we recorded the pressure and irrigant flow measurements. Measurements were made with an empty ureter, 6F ureteral catheter, occlusion balloon catheter, and ureteral access sheaths (10/12F and 12/14F). Three 1-minute trials for each condition were recorded in each of four kidneys. RESULTS Ureteral catheterization with both the 10/12F and the 12/14F ureteral access sheaths resulted in significantly decreased intrarenal pressures in the pressure range tested compared with an empty ureter, a ureteral catheter, or an occlusion balloon application. Total irrigant flow for the 12/14F ureteral access sheath was significantly higher than for the empty ureter, ureteral catheter, or occlusion balloon in the entire pressure range evaluated. CONCLUSIONS In this in vitro cadaveric model, application of the ureteral access sheath during percutaneous nephrolithotomy resulted in decreased intrarenal pressures and increased irrigant flow.

Prospective Randomized Comparison of a Combined Ultrasonic and Pneumatic Lithotrite with a Standard Ultrasonic Lithotrite for Percutaneous Nephrolithotomy

PURPOSE To compare the efficiency and cost effectiveness of a combined pneumatic and ultrasonic lithotrite (Lithoclast Ultra) and a standard ultrasonic lithotrite, (LUS-1) during percutaneous nephrolithotomy. MATERIALS AND METHODS In a prospective randomized trial, 30 patients undergoing percutaneous nephrolithotomy (PCNL) were randomized to PCNL with either the combined pneumatic and ultrasonic lithotrite (PUL) or a standard ultrasonic lithotrite (SUL). Patient demographics, stone composition, location, pre- and post-operative stone burden, fragmentation rates, and device failures were compared. RESULTS There were 13 patients in the PUL group and 17 patients in the SUL group. Stone burden and location were equal. Overall, 64% of the PUL group had hard stones (defined as stones that were either pure or a mixture of cystine [3], calcium oxalate monohydrate [CaOxMono; 2], and calcium phosphate [CaPO4; 2]), and four had soft stones (3 struvite and 1 uric acid [UA]). In the SUL group, there were eight hard stones (5 CaOxMono and 3 CaPO4), and six soft stones (4 calcium oxalate dihydrate [CaOxDi] and 2 UA) (P = 0.51). Stone composition data were unavailable for five patients. Fragmentation time for the PAL was 37 minutes versus 31.5 minutes for the SUL (P = 0.22). Stone retrieval and mean operative times were similar for both groups. There were a total of three (23.1%) device-related problems in the PUL group, and eight (47%) in the SUL group. There was one (7.7%) device malfunction in the PUL group due to probe fracture. There were two (11.7%) device failures in the SUL group; one failure required the device to be reset every 30 minutes, and the second was an electrical failure. Suction tubing obstruction occurred twice (15.3%) in the PUL group and 35.3% in the SU group (P = 0.35). The stone-free rates for the PUL and SUL were 46% and 66.7%, respectively (P = 0.26). CONCLUSION Although the PUL was more costly, stone ablation and clearance rates were similar for both the combined pneumatic and ultrasonic device and the standard ultrasonic device. When stratified with respect to stone composition, the PUL was more efficient for harder stones, and the SUL was more efficient for softer stones.