Kenneth Ogan

Percutaneous radiofrequency ablation of renal tumors: technique, limitations, and morbidity

OBJECTIVESnTo evaluate our evolving experience with percutaneous radiofrequency (RF) renal tumor ablation and focus on our technique to ensure maximal treatment efficacy and reduce the possibility of complications.nnnMETHODSnFifteen patients with small (less than 4 cm) posterior or lateral contrast-enhancing (more than 10 Hounsfield units) renal tumors were candidates for RF treatment. Of these patients, 12 (13 tumors) received computed tomography-guided percutaneous RF ablation. General anesthesia was administered in all but our first 2 patients, who received intravenous sedation. After treatment, patients were closely followed up with computed tomography scans at 6 weeks and 3, 6, and 12 months, and every 6 months thereafter. Successful ablation was defined as a lesion along with a margin of normal parenchyma that no longer enhanced (less than 10 Hounsfield units) on follow-up contrast imaging.nnnRESULTSnThe mean tumor size was 2.4 +/- 0.6 cm. The average procedure time was 95 minutes (range 60 to 150) and length of stay 0.9 days. All patients underwent the procedure without any major complications. At a mean follow-up of 4.9 months, 12 (93%) of 13 tumors were successfully ablated. In 3 patients, the procedure was not performed because of intervening bowel or lung parenchyma when positioned in the prone position before the procedure. Computed tomography-guided percutaneous RF ablation of small renal tumors is a viable minimally invasive treatment option with a high short-term success rate and low morbidity. This new technology must be uniformly applied to assess its long-term efficacy.

Assessment of basic endoscopic performance using a virtual reality simulator

BACKGROUNDnThe objective of this study was to evaluate the effect of supervised training using a state-of-the-art virtual reality (VR) genitourinary endoscopy simulator on the basic endoscopic skills of novice endoscopists.nnnSTUDY DESIGNnWe evaluated 21 medical students performing an initial VR case scenario (pretest) requiring rigid cystoscopy, flexible ureteroscopy with laser lithotripsy, and basket retrieval of a proximal ureteral stone. All students were evaluated with objective parameters assessed by the VR simulator and by two experienced evaluators using a global rating scale. Students were then randomized to a control group receiving no further training or a training group, which received five supervised training sessions using the VR simulator. All students were then evaluated again in the same manner using the same case scenario (posttest).nnnRESULTSnComparing the results of pre- and posttests, no major differences were demonstrated for any variable in the control group. In the trained group, posttest results revealed statistically significant improvement from baseline in the following parameters: total procedure time (p = 0.002), time to introduce a ureteral guidewire (p = 0.039), self-evaluation (p < 0.001), and evaluator assessment (p < 0.001). Comparing the posttest results of the control and trained arms, we found significantly better posttest scores in the trained group for the following parameters: ability to perform the task (p = 0.035), overall performance (p = 0.004), and total evaluator score (p < or = 0.001).nnnCONCLUSIONSnStudents trained on the VR simulator demonstrated statistically significant improvement on repeat testing, but the control group showed no improvement. Endourologic training using VR simulation facilitates performance of basic endourologic tasks and might translate into better performance in the operating room.

LAPAROSCOPIC APPLICATION OF RADIO FREQUENCY ENERGY ENABLES IN SITU RENAL TUMOR ABLATION AND PARTIAL NEPHRECTOMY

PURPOSEnTo our knowledge we present the initial series of renal mass in situ laparoscopic radio frequency ablation. We also discuss the indications for and results of subsequent laparoscopic partial nephrectomy.nnnMATERIALS AND METHODSnLaparoscopic radio frequency ablation was performed in 13 patients with a mean age of 59 years (range 18 to 81) and a total of 17 small enhancing renal masses. In 5 patients the tumor was subsequently excised completely, whereas in 7 it was left in situ after treatment. In 1 patient with 5 lesions only the largest lesion was excised, while the other 4 were left in situ.nnnRESULTSnMean tumor size was 1.96 cm. (range 0.9 to 3.6). Tumors that remained in situ tended to be endophytic and located in the mid pole. Pathological analysis revealed renal cell carcinoma in 10 patients, angiomyolipoma in 2 and oncocytoma in the patient with multiple lesions. None of the 8 patients with renal cell carcinoma who had at least 6 weeks of followup (mean 9.8 months, range 1.5 to 22) had any evidence of persistent tumor enhancement on surveillance computerized tomography or any other evidence of disease progression. There was 1 focal positive margin in a patient who underwent radio frequency ablation and excision of renal cell carcinoma but the patient remained disease-free 1 year after treatment.nnnCONCLUSIONSnEarly experience with laparoscopic radio frequency ablation in situ or combined with partial nephrectomy shows that it appears to be a safe method of managing small enhancing renal masses. Radio frequency assisted laparoscopic partial nephrectomy is reserved for easily accessible exophytic tumors, while strict surveillance is required for lesions remaining in situ after ablation. Additional followup is required to assess long-term effectiveness.

Sutureless laparoscopic heminephrectomy using laser tissue soldering.

BACKGROUND AND PURPOSEnWidespread application of laparoscopic partial nephrectomy has been limited by the lack of a reliable means of attaining hemostasis. We describe laser tissue welding using human albumin as a solder to control bleeding and seal the collecting system during laparoscopic heminephrectomy in a porcine model.nnnMATERIALS AND METHODSnLaparoscopic left lower-pole heminephrectomy was performed in five female domestic pigs after occluding the hilar vessels. Using an 810-nm pulsed diode laser (20 W), a 50% liquid albumin-indocyanine green solder was welded to the cut edge of the renal parenchyma to seal the collecting system and achieve hemostasis. Two weeks later, an identical procedure was performed on the right kidney, after which, the animals were sacrificed and both kidneys were harvested for ex vivo retrograde pyelograms and histopathologic analysis.nnnRESULTSnAll 10 heminephrectomies were performed without complication. The mean operative time was 82 minutes, with an average blood loss of 43.5 mL per procedure. The mean warm ischemia time was 11.7 minutes. For each heminephrectomy, a mean of 4.2 mL of solder was welded to the cut parenchymal surface. In three of the five acute kidneys and all five 2-week kidneys, ex vivo retrograde pyelograms demonstrated no extravasation. In addition, no animal had clinical evidence of urinoma or delayed hemorrhage. Histopathologic analysis showed preservation of the renal parenchyma immediately beneath the solder.nnnDISCUSSIONnLaser tissue welding provided reliable hemostasis and closure of the collecting system while protecting the underlying parenchyma from the deleterious effect of the laser during porcine laparoscopic heminephrectomy.

Minimally Invasive Management of the Small Renal Tumor: Review of Laparoscopic Partial Nephrectomy and Ablative Techniques

The most profound change among the many that have occurred in the management of renal-cell carcinoma (RCC) in recent years is the advent of nephron-sparing surgery for masses <4 cm. The main challenge now is to reduce the morbidity associated with such procedures. Because of the problems in obtaining hemostasis, only a few highly experienced surgeons are performing partial nephrectomy laparoscopically. Numerous techniques and tools have been studied, including laparoscopic duplication of the open operation; hand-assisted surgery; double-loop and cable-tie tourniquets; ultrasonic shears; radiofrequency, microwave, and laser energy; the Endosnare; and hydro-jet dissection. Also, ablation with cold, radiofrequency energy, or high-intensity focused ultrasound is being explored. Just as open surgery for urolithiasis has been all but replaced by extracorporeal lithotripsy and endoscopic techniques, treatment of most RCCs will ultimately shift from open to minimally invasive methods.

Infrared thermography and thermocouple mapping of radiofrequency renal ablation to assess treatment adequacy and ablation margins

OBJECTIVESnThe primary disadvantage of renal tumor RF ablation is the inability to monitor the intraoperative propagation of the RF lesion with real-time imaging. We sought to assess whether adequately lethal temperatures are obtained at the margins of the intended ablation zone using laparoscopic thermography to monitor radiofrequency (RF) lesions in real time, thermocouple measurements, and histopathologic evaluation.nnnMETHODSnRenal RF lesions were created under direct laparoscopic vision in the upper (1 cm diameter) and lower (2 cm) poles of the right kidney in 5 female pigs. The RF lesions were produced with the RITA generator and probe, set at 105 degrees C for 5-minute ablations. During RF treatment, a laparoscopic infrared (IR) camera measured the surface parenchymal temperatures, as did multiple thermocouples. The pigs were then either immediately killed (n = 3) or allowed to live for 2 weeks (n = 2). The kidneys were removed to correlate the temperature measurements with histologic analysis of the ablated lesion.nnnRESULTSnUsing a threshold temperature of greater than 70 degrees C for visual temperature color change, the IR camera identified the region of pathologic necrosis of the renal parenchyma during RF ablation. Thermocouple measurements demonstrated that the temperatures at the intended ablation radius reached 77.5 degrees C at the renal surface and 83.7 degrees C centrally, and temperatures 5 mm beyond the set radius reached 52.6 degrees C at the surface and 47.7 degrees C centrally. The average diameter of the gross lesion on the surface of the kidney measured 17.1 mm and 22.4 mm for 1-cm and 2-cm ablations, respectively. These surface measurements correlated with an average diameter of 16.1 mm and 15.9 mm (1-cm and 2-cm ablations, respectively) as measured with the IR camera. All cells within these ablation zones were nonviable by nicotinamide adenine dinucleotide diaphorase analysis. The average depth of the lesions measured 19 mm (1-cm ablation) and 25 mm (2-cm ablation) on gross histologic examination.nnnCONCLUSIONSnThe laparoscopic IR camera is able to monitor the surface renal temperatures during RF treatment. Thermocouple measurements during RF ablation confirmed the thermographic findings and demonstrated that lethal temperatures at the margin of the intended treatment zone are routinely obtained and that a rapid decline in temperature occurs beyond the predicted ablation margin.

Laparoscopic versus open retroperitoneal lymph node dissection: a cost analysis.

PURPOSEnLaparoscopic retroperitoneal lymph node dissection is significantly less morbid than open retroperitoneal lymph node dissection but it is generally more costly due to longer operative time and disposable equipment. In response to budgetary pressure at our large county hospital we identified the cost components of laparoscopic retroperitoneal lymph node dissection that could be targeted to decrease procedure costs before expanding our laparoscopic retroperitoneal lymph node dissection program.nnnMATERIALS AND METHODSnA comprehensive literature review of open and laparoscopic retroperitoneal lymph node dissection was performed and certain parameters were abstracted, including operative time and equipment, hospital stay, perioperative complications and surgical success rates. Using these data the projected overall cost and individual cost centers at our institution were compared for open and laparoscopic retroperitoneal lymph node dissection. Decision tree analysis models were devised to estimate the cost of each treatment using commercially available software. We performed 1 and 2-way sensitivity analysis to evaluate the effect of individual treatment variables on overall cost. Base case analysis involved a young man with clinical stage I nonseminomatous testicular cancer who was a candidate for retroperitoneal lymph node dissection.nnnRESULTSnBased on a review of the costs at our institution open retroperitoneal lymph node dissection was a less costly procedure at

Ureteral replacement using small-intestinal submucosa and a collagen inhibitor in a porcine model.

7,162 versus

Feasibility of Laparoscopic Partial Nephrectomy Using Pledgeted Compression Sutures for Hemostasis

7,804 for the laparoscopic approach. The slight cost superiority of the open approach was due to significantly lower costs associated with operating room time and equipment. On the other hand, the laparoscopic procedure showed a cost advantage for hospital stay. On 1-way sensitivity analysis laparoscopic dissection was less costly when operative time was less than 3.6 hours, hospitalization was less than 2.2 days or laparoscopic equipment costs were less than

Oops we got in the chest: fluoroscopic chest tube insertion for hydrothorax after percutaneous nephrostolithotomy

768. On 2-way sensitivity analysis the laparoscopic approach was cost advantageous when performed in less than 5 hours or when the patient was discharged home within 2 days postoperatively.nnnCONCLUSIONSnThe primary cost variables for surgical treatment for testicular cancer include operative time, hospital stay and equipment cost. According to published data and decision tree analysis open retroperitoneal lymph node dissection is slightly less costly (less than