Hernan O. Altamar

Selective Renal Parenchymal Clamping in Robotic Partial Nephrectomy: Initial Experience

OBJECTIVES To describe our early experience using a laparoscopic clamp to induce selective regional ischemia during robotic-assisted partial nephrectomy without hilar occlusion. The creation of a bloodless field during minimally invasive approaches to nephron-sparing surgery often requires complete warm ischemia with renal hilar clamping that can potentially result in subsequent renal damage. METHODS After transperitoneal renal mobilization and delineation of the renal tumor margin using laparoscopic ultrasound, the laparoscopic clamp is placed across the renal parenchyma 2-3 cm proximal to the resection line. After tumor excision, the renal defect is repaired robotically and hemostatic agents are used to aid in achieving compressive hemostasis. RESULTS Three patients with predominantly exophytic renal masses underwent this procedure for elective indications. Mean tumor diameter was 4.9 cm (range 1.2-7.0). Mean selective clamp time was 37 minutes (range 20-52). Estimated blood loss was minimal and no patients required renal hilar clamping. There were no perioperative complications. Mean change in preoperative and postoperative creatinine was 0.1 (±0.09). Final pathology revealed clear cell and papillary renal carcinomas with no positive margins on frozen or final evaluation. CONCLUSIONS Regional renal parenchymal clamping during robotic partial nephrectomy can be safely and effectively used to create a bloodless operative field in select patients with optimally located renal tumors. Our early experience with this technique allows for frozen pathologic evaluation of the tumor and margin status without concern for warm ischemia and represents another tool for surgeons performing minimally invasive nephron-sparing surgery.

Kidney deformation and intraprocedural registration: a study of elements of image-guided kidney surgery.

INTRODUCTION Central to any image-guided surgical procedure is the alignment of image and physical coordinate spaces, or registration. We explored the task of registration in the kidney through in vivo and ex vivo porcine animal models and a human study of minimally invasive kidney surgery. METHODS A set of (n = 6) ex vivo porcine kidney models was utilized to study the effect of perfusion and loss of turgor caused by incision. Computed tomography (CT) and laser range scanner localizations of the porcine kidneys were performed before and after renal vessel clamping and after capsular incision. The da Vinci robotic surgery system was used for kidney surface acquisition and registration during robot-assisted laparoscopic partial nephrectomy. The surgeon acquired the physical surface data points with a tracked robotic instrument. These data points were aligned to preoperative CT for surface-based registrations. In addition, two biomechanical elastic computer models (isotropic and anisotropic) were constructed to simulate deformations in one of the kidneys to assess predictive capabilities. RESULTS The mean displacement at the surface fiducials (glass beads) in six porcine kidneys was 4.4 ± 2.1 mm (range 3.4-6.7 mm), with a maximum displacement range of 6.1 to 11.2 mm. Surface-based registrations using the da Vinci robotic instrument in robot-assisted laparoscopic partial nephrectomy yielded mean and standard deviation closest point distances of 1.4 and 1.1 mm. With respect to computer model predictive capability, the target registration error was on average 6.7 mm without using the model and 3.2 mm with using the model. The maximum target error reduced from 11.4 to 6.2 mm. The anisotropic biomechanical model yielded better performance but was not statistically better. CONCLUSIONS An initial point-based alignment followed by an iterative closest point registration is a feasible method of registering preoperative image (CT) space to intraoperative physical (robot) space. Although rigid registration provides utility for image-guidance, local deformations in regions of resection may be more significant. Computer models may be useful for prediction of such deformations, but more investigation is needed to establish the necessity of such compensation.

A multicenter comparison of the safety and effectiveness of ureteroscopic laser lithotripsy in obese and normal weight patients.

OBJECTIVE Surgical treatment of kidney stones in an obese patient (body mass index [BMI] >30 kg/m(2)) remains challenging as shockwave lithotripsy may not be an option due to weight limitations. We sought to determine the effectiveness of ureteroscopic laser lithotripsy in obese patients compared to nonobese controls. MATERIALS AND METHODS Patients from 2004 to 2007 were retrospectively analyzed providing a group of 292 patients (163 obese, 76 overweight, 53 normal) who underwent ureteroscopic procedures for urolithiasis at four centers in the United States and Canada. RESULTS The percentage of obese patients requiring flexible ureteroscopy (URS) (79%) was higher than in the other groups (P<0.0001). Flexible URS was associated with a lower stone-free rate (SFR) on multivariate analysis (P=0.034). There was no difference in SFRs of patients who required a ureteral access sheath, basket extraction, or received a postoperative stent. Complication rates did not differ between groups. CONCLUSION SFRs using ureteroscopic lithotripsy in obese and overweight populations are the same as in the normal weight patients. A flexible ureteroscope was associated with a decreased SFR, but this likely due to a more proximal stone location in these patients. Ureteroscopic laser lithotripsy is an effective and safe technique to treat urolithiasis in the overweight/obese patient.

Second Prize: A Sealed Bladder Cuff Technique During Laparoscopic Nephroureterectomy Utilizing the LigaSure™ Electrosurgical Device: Laboratory and Clinical Experience

INTRODUCTION Laparoscopic nephroureterectomy (LNU) is a safe, minimally invasive approach for management of upper tract urothelial tumors. Controversy exists over the optimal technique for the distal ureter and bladder cuff (DUBC) excision. We examined the novel technique of using the LigaSure bipolar electrosurgical device in laboratory investigations and during clinical LNU to manage the DUBC. PATIENTS AND METHODS Initial investigations were undertaken in the porcine model. Areas of both normal porcine ureters and bladders, and ex vivo human ureters from radical nephrectomy specimens were sealed with the LigaSure and stained with nicotinamide adenine dinucleotide (NADH) and hematoxylin and eosin to examine the length of treatment effect and the viability of the ablated tissue. Clinically, we performed 22 LNU for proximal urothelial tumors using the LigaSure for the management of the DUBC. Intraoperative cystoscopy assessed cuff resection and bladder leakage. On postoperative day 10, a cystogram was performed. RESULTS In the porcine model, the technique sealed the bladder effectively with a mean burst pressure of 14 mm Hg. Cellular staining revealed no viable urothelial tissue in the seal area and an additional 2 mm outside this area. Eighteen patients had a successful seal/ablation intraoperatively. Cystoscopy revealed cautery artifact and blanching over the former position of the ureteral orifice. CONCLUSION The LigaSure device ablates and seals urothelial tissue with no viable cells in the clamped and adjacent blanched tissue. Our technique is technically feasible, removes an adequate bladder cuff, typically maintains a closed urinary system, and adheres to sound oncological principles. This procedure could be performed in both laparoscopic and open nephroureterectomy for proximal upper tract transitional cell tumors.

Intraprocedural Registration for Image-Guided Kidney Surgery

This paper reviews the process of using surface-based registration techniques for image-guided kidney surgery and presents data for both open and minimally invasive kidney surgery either by robot or by hand.

Intraoperative Retrograde Ureteral Stent Placement and Manipulation During Laparoscopic Pyeloplasty Without Need for Patient Repositioning

Ureteral stent placement during adult laparoscopic pyeloplasty for ureteropelvic junction obstruction can be performed preoperatively or intraoperatively either in a retrograde or antegrade approach. Intraoperative retrograde stent placement is the most commonly used technique. Comparative studies, however, suggest that there is a significant component added to the overall operative times because of the need for patient repositioning from the lithotomy to the flank position before pyeloplasty. During our laparoscopic pyeloplasty surgery, we position the patient in the lateral decubitus position and incorporate a lower extremity support device for female patients. This allows initial open-ended catheter placement and subsequent access to the perineum and final stent placement throughout the procedure without need for patient repositioning. In addition, our technique allows for intraoperative fluoroscopy to delineate the complete ureteral anatomy. Since 2004, we have used this approach in 111 consecutive patients without complications. We describe our technique for intraoperative ureteral stent placement in the flank position during adult laparoscopic pyeloplasty without need for patient repositioning.

Comparison and assessment of semi-automatic image segmentation in computed tomography scans for image-guided kidney surgery

PURPOSE Image segmentation is integral to implementing intraoperative guidance for kidney tumor resection. Results seen in computed tomography (CT) data are affected by target organ physiology as well as by the segmentation algorithm used. This work studies variables involved in using level set methods found in the Insight Toolkit to segment kidneys from CT scans and applies the results to an image guidance setting. METHODS A composite algorithm drawing on the strengths of multiple level set approaches was built using the Insight Toolkit. This algorithm requires image contrast state and seed points to be identified as input, and functions independently thereafter, selecting and altering method and variable choice as needed. RESULTS Semi-automatic results were compared to expert hand segmentation results directly and by the use of the resultant surfaces for registration of intraoperative data. Direct comparison using the Dice metric showed average agreement of 0.93 between semi-automatic and hand segmentation results. Use of the segmented surfaces in closest point registration of intraoperative laser range scan data yielded average closest point distances of approximately 1 mm. Application of both inverse registration transforms from the previous step to all hand segmented image space points revealed that the distance variability introduced by registering to the semi-automatically segmented surface versus the hand segmented surface was typically less than 3 mm both near the tumor target and at distal points, including subsurface points. CONCLUSIONS Use of the algorithm shortened user interaction time and provided results which were comparable to the gold standard of hand segmentation. Further, the use of the algorithms resultant surfaces in image registration provided comparable transformations to surfaces produced by hand segmentation. These data support the applicability and utility of such an algorithm as part of an image guidance workflow.

The current status of robot-assisted laparoscopic prostatectomy.

Purpose of review To review the recent urologic literature with a focus on refinements of surgical technique in robot-assisted laparoscopic prostatectomy (RALP) and to discuss the impact of these developments on the ‘trifecta’ of prostate cancer management: oncologic, continence, and potency outcomes. Recent findings Refinements in the surgical technique during the established steps of radical prostatectomy have led to improved functional outcomes following RALP. Early continence rates have increased, and potency, with evolving respect for the neurovascular bundle and neural anatomy, has further promise. ‘Long-term’ outcomes demonstrate favorable results in continence and potency. Oncologic outcomes, specifically low positive margin rates, have been maintained and even improved in many series during the evolution of this widely accepted procedure. Summary RALP has continued to rapidly disseminate through the urologic community, but the ultimate impact remains under scrutiny. The procedure has seen birth from open and laparoscopic prostatectomy, and its success has been measured against contemporary open prostatectomy series during its infancy. Short and long-term oncologic outcomes must be followed carefully. The assessment of functional outcomes of continence and potency requires honest and, as best possible, objective analysis. Prospective, randomized clinical trials with long-term follow-up utilizing validated instruments are necessary to evaluate RALP and all associated technical modifications.