Kamyar Ebrahimi

Fluoroscopic Organ and Tissue-Specific Radiation Exposure by Sex and Body Mass Index During Ureteroscopy

INTRODUCTION Although radiation exposure from CT and plain film imaging has been characterized, the radiation received by patients during modern-era fluoroscopy has not been well described. The purposes of this study were to measure absolute organ and tissue-specific radiation doses during ureteroscopy and to determine the influence of body mass index (BMI) and sex on these doses. MATERIALS AND METHODS Eight cadavers underwent a simulated left ureteroscopy. Using a modern C-arm with automatic exposure control settings, thermoluminescent dosimeters were exposed for a fluoroscopy time of 145 seconds (mean time of clinical ureteroscopies from 2006 to 2008). Total tissue exposures were compared by BMI and between sexes using the Wilcoxon signed ranks test and the Mann-Whitney test with p < 0.05 considered significant. RESULTS Among all cadavers, radiation doses were significantly lower in all contralateral organs excluding the gonad (p < 0.012). Doses were similar bilaterally in the gonad in cadavers with BMI <30, and in all organs in cadavers with BMI >30 (p > 0.05). There were significantly higher mean bilateral gonadal doses in female cadavers (3.4 mGy left and 1.9 mGy right) compared with male cadavers (0.36 mGy left and 0.39 mGy right). The highest cancer risk increase was seen at the posterior skin equivalent to 104 additional cancers per 100,000 patients. CONCLUSION Contralateral doses were lower for all organs except the gonad when the BMI was <30. In contrast, when the BMI was >30, there was no difference in radiation dose delivered to the ipsilateral and contralateral organs. Gonadal doses were significantly higher in female cadavers. Modern-era fluoroscopy remains a significant source of radiation exposure and steps should be taken to minimize exposure during ureteroscopy.

Factors that impact the outcome of minimally invasive pyeloplasty: Results of the multi-institutional laparoscopic and robotic pyeloplasty collaborative group

PURPOSE We compared laparoscopic and robotic pyeloplasty to identify factors associated with procedural efficacy. MATERIALS AND METHODS We conducted a retrospective multicenter trial incorporating 865 cases from 15 centers. We collected perioperative data including anatomical and procedural factors. Failure was defined subjectively as pain that was unchanged or worse per medical records after surgery. Radiographic failure was defined as unchanged or worsening drainage on renal scans or worsening hydronephrosis on computerized tomography. Bivariate analyses were performed on all outcomes and multivariate analysis was used to assess factors associated with decreased freedom from secondary procedures. RESULTS Of the cases 759 (274 laparoscopic pyeloplasties with a mean followup of 15 months and 465 robotic pyeloplasties with a mean followup of 11 months, p <0.001) had sufficient data. Laparoscopic pyeloplasty, previous endopyelotomy and intraoperative crossing vessels were associated with decreased freedom from secondary procedures on bivariate analysis, with a 2-year freedom from secondary procedures of 87% for laparoscopic pyeloplasty vs 95% for robotic pyeloplasty, 81% vs 93% for patients with vs without previous endopyelotomy and 88% vs 95% for patients with vs without intraoperative crossing vessels, respectively. However, on multivariate analysis only previous endopyelotomy (HR 4.35) and intraoperative crossing vessels (HR 2.73) significantly impacted freedom from secondary procedures. CONCLUSIONS Laparoscopic and robotic pyeloplasty are highly effective in treating ureteropelvic junction obstruction. There was no difference in their abilities to render the patient free from secondary procedures on multivariate analysis. Previous endopyelotomy and intraoperative crossing vessels reduced freedom from secondary procedures.

Hybrid Transureteral Natural Orifice Translumenal Endoscopic Nephrectomy: A Feasibility Study in the Porcine Model

BACKGROUND AND PURPOSE Natural orifice approaches for nephrectomy have included access via the stomach, vagina, bladder, and rectum. The use of the ureter as a natural orifice for natural orifice translumenal endoscopic surgery (NOTES) nephrectomy has not been previously reported. The purpose of this study is to test the feasibility of transureteral laparoscopic NOTES nephrectomy. MATERIALS AND METHODS Three female farm pigs (29.2-30.8 kg) were placed into the lithotomy position. A cystoscopically placed extra-stiff guidewire was used to place a prototype dilating sheath into the left ureter. After dilation of the ureter and urethra, the sheath was exchanged for a 12-mm bariatric laparoscopic trocar. A 10.5-inch long 10-mm offset operating laparoscope with an internal 5-mm working port was used for the nephrectomy. One 2-mm and one 2/3-mm port were placed transabdominally to facilitate in situ morcellation. The kidney was cut into slices using the bipolar device and extracted via the ureteral port using the housing of a 12-mm bariatric stapling device. RESULTS All three transureteral nephrectomies were successfully completed. The total mean operative time was 220 minutes (range 113-346 min). Component portions of the procedure were: Ureteral access (mean 21 min), nephrectomy (mean 70 min), and kidney morcellation (mean 103 min). Mean estimated blood loss was 20 mL (range 5-50 mL). There were no intraoperative complications. CONCLUSIONS This nonsurvival porcine feasibility study demonstrates the successful performance of transureteral nephrectomy. This approach shows promise as a way to decrease the invasiveness of NOTES nephrectomy by using the ureteral orifice as an access site.

Comparison of a Novel Radially Dilating Balloon Ureteral Access Sheath to a Conventional Sheath in the Porcine Model

PURPOSE Traditional ureteral access sheaths rely on tapered dilators and the Dotter principle of axial force to gain access into the ureter. We compared the performance of a novel balloon expandable ureteral access sheath using radial dilatation with that of a conventional ureteral access sheath. MATERIALS AND METHODS Ten farm pigs underwent randomized placement of the novel sheath in 1 ureter and a conventional ureteral access sheath in the contralateral ureter followed by videotaped ureteroscopy. Acute study end points included maximum and mean force of sheath insertion and removal, saline flow rate and subjective urothelial damage following sheath insertion/inflation. Additionally, blinded reviewers rated urothelial damage on digitally recorded video following sheath removal. Chronic data included gross and histological ureteral analysis at 30 days. RESULTS The novel ureteral access sheath inserted with less maximum force (0.36 vs 1.48 pounds, p <0.001) and less average force (0.11 vs 0.49 pounds, p = 0.001). The flow rate during 5 minutes was higher in the new sheath (90.0 vs 80.6 cc per minute, p <0.05). Withdrawal forces were not statistically different between the sheaths. The novel sheath also had a lower subjective trauma scale rating (4.2 vs 6.1, p <0.05). Eight blinded reviewers determined that the novel ureteral access sheath resulted in less total urothelial tear length (1.3 vs 2.7 cm, p = 0.03) and less visible ureteral damage in all animals except 1 (p = 0.04). CONCLUSIONS The novel balloon expandable ureteral access sheath had easier insertion and a better flow rate, and caused less urothelial trauma in this porcine model. This ureteral access sheath offers a promising new option for ureteral access. A randomized clinical trial is in progress to assess the benefits of this new ureteral access sheath.

Hemostatic Sandwich to Control Percutaneous Nephrolithotomy Tract Bleeding

BACKGROUND AND PURPOSE Significant bleeding necessitating use of a tamponade balloon, embolization, or renal exploration is a rare but catastrophic complication after percutaneous nephrolithotomy (PCNL). The purpose of this study is to review the success of a novel, minimally invasive technique for controlling percutaneous tract bleeding that is refractory to conventional measures. MATERIALS AND METHODS A retrospective review was performed on four patients with refractory tract hemorrhage that was managed with a novel gelatin matrix hemostatic sandwich technique. In this technique, a 5F angiographic reentry catheter was placed through the kidney into the bladder and a 22F Councill-tip catheter balloon was passed over this catheter and positioned so that the inflated balloon would occlude the inner surface of the nephrostomy tract. Next, a 16F Councill-tip catheter was placed over a second wire so that the uninflated balloon was just underneath the skin surface. Gelatin matrix hemostatic sealant was then injected to fill the tract. Inflation of the outer balloon completely sealed the tract, completing the hemostatic sandwich. RESULTS This technique was successfully applied to four patients with tract bleeding that would not stop with pressure or a conventional nephrostomy tube alone. The average estimated blood loss was 562 mL, and three of four patients avoided transfusion. All postoperative hemoglobin values stabilized within 2 days of surgery. There were no major or minor complications after use of this technique. No patients needed angioembolization or renal exploration. CONCLUSIONS This novel hemostatic sandwich technique should be considered as an option for the control of refractory tract hemorrhage after PCNL.

A Novel Bridging Hand-Assisted LESS Donor Nephrectomy Technique

Abstract Objectives: To address the significant shortage of kidneys available for transplant, laparoendoscopic single-site surgery (LESS) has been employed to further decrease the morbidity of kidney donation. To circumvent the complexity of LESS, we have developed a bridging hand-assisted LESS (BLESS) technique that allows the surgeon to gain experience with single-incision surgical techniques in the setting of traditional hand-assisted laparoscopy. Methods: A retrospective study of three patients undergoing BLESS donor nephrectomy was performed. Similar to LESS, this bridging technique employs a single periumbilical incision, but enlargement of the incision by a few centimeters facilitates immediate transition to hand-assisted laparoscopy if needed. Statistics on preoperative, perioperative, and postoperative variables was collected for the patients undergoing this procedure. Results: BLESS patients had a mean age of 31. Average postoperative hospital stay was short at 1.34 days, with two of the three p...