Biomedical subjects

William W Roberts

Publications and source records attributed to William W Roberts.

At least 19 recordsLinked to original sources

PubMed2006

Characterization and management of postoperative hemorrhage following upper retroperitoneal laparoscopic surgery.

PURPOSE: Surgical paradigms may change in the era of laparoscopic surgery. We evaluated a conservative nonsurgical approach to postoperative hemorrhage following laparoscopic upper retroperitoneal surgery as opposed to the more traditional strategy of reexploring the surgical site. MATERIALS AND METHODS: In 911 laparoscopic procedures performed in 8 years we retrospectively identified risk factors and characterized treatment for postoperative hemorrhage. RESULTS: We considered postoperative hemorrhage to be present when postoperative transfusion was required that could not be accounted for by operative blood loss or another definable cause outside of the surgical field. Red blood cell transfusion was required after 53 procedures (5.8%), of which 34 (3.7%) were done for postoperative hemorrhage. Postoperative hemorrhage occurred only after nephrectomy in 3.3% of cases, after partial nephrectomy in 9.9% and after adrenalectomy in 5.4%. Multivariate analysis revealed a significant association of postoperative hemorrhage with patient age and American Society of Anesthesiologists score (preoperative factors), operative time and splenic injury (intraoperative factors), and gastrointestinal complications and prolonged hospitalization (postoperative factors). Postoperative hemorrhage increased mean hospitalization from 2.5 to 6.4 days. No significant differences in post-hospital recovery were associated with postoperative hemorrhage. Only 4 of the 34 patients (12%) required surgical management of postoperative hemorrhage. All other cases were conservatively managed. Outcome after surgical and conservative management did not differ except postoperative renal complications tended to be more common in the former cases (50% vs 7%). CONCLUSIONS: Most patients with hemorrhage following laparoscopic upper retroperitoneal surgery can be treated with conservative nonsurgical interventions.

Adrenalectomy↗

PubMed2006

Surgical management of low-stage renal cell carcinoma: Technology does not supersede biology.

OBJECTIVES: To address the concern that laparoscopic radical nephrectomy (LRN) is being applied in cases of small renal masses in which nephron-sparing surgery (NSS) might be more appropriate. METHODS: From 1998 to 2003, 381 consecutive patients underwent 391 procedures at our institution for renal cell carcinoma, of which 336 were for organ-confined tumors. The temporal trends in the application of LRN and NSS were assessed relative to the clinical stage. RESULTS: During the transition from early (1998 to 2000) to late (2001 to 2003) experience with laparoscopy, the use of LRN among patients with Stage T1a (4 cm or smaller) lesions remained infrequent (21% and 20%, respectively). In contrast, LRN increased among patients with larger lesions during this same interval (Stage T1b, 36% versus 56%, P = 0.017 and Stage T2, 24% versus 41%, P = 0.056). Concurrently, the use of NSS (open surgical or laparoscopic partial nephrectomy) increased for both Stage T1a (25% and 31% versus 34% and 37%, P = 0.082) and T1b (8% and 6% versus 19% and 5%, P = 0.017) tumors. Multivariate analysis demonstrated that the use of both NSS and LRN increased significantly with time (P = 0.002 and P = 0.001, respectively). Neither NSS nor LRN were associated with a greater risk of perioperative complications relative to radical or open surgery (P >0.05 for both). CONCLUSIONS: During a 6-year period at our institution, most Stage T1a lesions were managed with NSS, and a significant increase occurred in the use of NSS for Stage T1b tumors, despite the concurrent increasing application of LRN. These findings suggest that oncologic, rather than technologic, concerns were determining our practice patterns.

Carcinoma, Renal Cell↗

PubMed2006

Pulsed cavitational ultrasound: a noninvasive technology for controlled tissue ablation (histotripsy) in the rabbit kidney.

PURPOSE: The optimal minimally invasive treatment for small renal masses continues to evolve. Current ablative technologies rely on thermal mechanisms for tissue destruction. However, the creation of precise lesions is limited by inhomogeneous heating/cooling due to tissue variability, perfusion effects and tissue charring. We hypothesized that nonthermal mechanical effects of ultrasound (cavitation) can be used to progressively homogenize tissue in controlled fashion with predictable results. MATERIALS AND METHODS: We developed a focused annular array ultrasound system capable of delivering high intensity (greater than 20 kW/cm) short pulses (20 microseconds) of energy to a target volume. This system operates at a repetition frequency of 100 Hz, resulting in a low time averaged power output (approximately 5 W total acoustic output). Following approval from the institutional animal care committee a series of transcutaneous ablations were performed in the normal kidneys of 10 rabbits. RESULTS: Lesions created with a small number of pulses (10 or 100) produced scattered areas of damage characterized by focal hemorrhage and small areas of cellular injury in the targeted volume. Lesions created with greater numbers of pulses (1,000 or 10,000) demonstrated complete destruction of the targeted volume. Gross examination revealed that lesions contained a liquefied core with smooth walls and sharply demarcated boundaries. Histological examination demonstrated extensive areas of acellular debris surrounded by a narrow margin of cellular injury. CONCLUSIONS: This pulsed cavitational ultrasound system is capable of transcutaneous nonthermal destruction of renal tissue. Refinement of this technology for noninvasive ablation of small renal masses is currently under way.

Animals↗

PubMed2006

Importance of perioperative processes of care for length of hospital stay after laparoscopic surgery.

BACKGROUND AND PURPOSE: The technologic imperative has prompted the adoption of complex laparoscopic techniques by physicians with various degrees of skill. We sought to measure the impact of both case mix and physician practice (perioperative process/risk factors) on length of stay (LOS)-a common benchmark- after laparoscopic surgery. PATIENTS AND METHODS: We identified 911 patients undergoing laparoscopic retroperitoneal surgery between 1996 and 2004, who comprise our study population. Patients remaining in the hospital >5 days-the 90th percentile for the sample-were classified as having a prolonged LOS. Adjusted models were developed to determine the independent association of case mix and process measures with a prolonged LOS. The likelihood ratio test was used to discern the improvement of fit of the process model compared with the case-mix model. RESULTS: Among factors related to case mix and structure of care, increasing age (odds ratio [OR] 1.1; 95% CI 1.0, 1.2), less surgeon experience (OR 6.1; 95% CI 2.1, 17.2), male gender (OR 2.1; 95% CI 1.2, 4.0), and American Society of Anesthesiologists score of 3 or 4 (OR 7.2; 95% CI 2.2, 23.3) were independently associated with a prolonged LOS. The need for a transfusion (OR 9.4; 95% CI 33.9, 23.2), the development of a postoperative complication (OR 4.6; 95% CI 2.2, 9.5), and longer operative time (OR 1.5; 95% CI 1.3, 1.8) explained additional variation in prolonged LOS outcomes when considering perioperative process/risk factors in the model. Perioperative factors significantly improved the fit of the model (chi (2) statistic 101.8; p < 0.0001). CONCLUSIONS: Significant variation in outcomes is explained by factors describing aspects of surgical expertise. Variability in the surgical skill set is likely greatest during the laparoscopic learning curve, which raises a quality-of-care concern during the initial implementation of the technique. Policies attempting to smooth the laparoscopic learning curve, such as mentoring and skill measurement prior to credentialing, could improve the quality of care.

Aged↗

PubMed2006

Surgical management of upper tract transitional cell carcinoma.

Upper tract transitional cell carcinoma (TCC) accounts for approximately 5% of urothelial tumors. Surgical therapy for upper tract TCC is based on tumor grade, stage, location, and confounding factors of individual cases. Options for treatment range from minimally invasive procedures, such as ureteroscopy, to open nephroureterectomy. Laparoscopic nephroureterectomy is progressively eclipsing open nephroureterectomy in the surgical management of upper tract TCC. This article discusses the surgical options for managing upper tract TCC and their considerations for use.

Carcinoma, Transitional Cell↗

PubMed2005

Pathological stage does not alter the prognosis for renal lesions determined to be stage T1 by computerized tomography.

PURPOSE: Pathological stage has been the most widely used prognosticator for evaluating surgically managed cases of renal cell carcinoma. Minimally invasive surgical approaches are being increasingly used to treat small masses for which traditionally pathological information is lacking (morcellation) or absent (radio frequency ablation or cryoablation). Preoperative cross-sectional imaging by computerized tomography (CT) or magnetic resonance imaging has been used to stage renal tumors clinically but it can lead to variances with traditional pathological staging systems, particularly with respect to microscopic invasion beyond the renal capsule. In this study we assessed whether radiographically staged clinical T1 lesions that were pathological T1 behave differently than those that were clinical stage T1 and up staged to pT3a. MATERIALS AND METHODS: The records of 296 patients who underwent surgical treatment for renal cell carcinoma at The Johns Hopkins Hospital between 1990 and 1999 were retrospectively reviewed. All patients had undergone preoperative CT or magnetic resonance imaging, which was used to assign a clinical stage and size (largest diameter) to each tumor in accordance with the 1997 TNM staging system. Following surgical resection pathological stage, size and tumor grade were determined. Only the 186 patients with clinical T1 tumors were included in this analysis. RESULTS: Of the 186 patients who were clinically found to have T1 lesions 125 (67%) had pathological T1 and 57 (31%) had pathological T3a lesions. All surgical margins and lymph nodes were negative at surgical resection. Mean tumor size +/- SD was 3.9 +/- 1.5 cm for pT1 lesions and 3.8 +/- 1.5 cm for pT3a lesions. When comparing these pathological groups using Kaplan-Meier analysis, 5-year recurrence-free survival was not statistically different in patients with pT1 and pT3a lesions (90.6 and 97.5%, respectively). CONCLUSIONS: Patients in whom the initial classification of T1 renal cell carcinoma by CT was up graded to T3a on pathological analysis (invasion of fat within Gerota's fascia) showed the same recurrence-free survival rate as patients with pathologically confirmed T1 lesions. Thus, smaller tumors (less than 7 cm) that are up graded to T3a based on capsule invasion behave much like T1 tumors and exact pathological T staging does not appear to impact overall survival.

Carcinoma, Renal Cell↗

PubMed2005

Laparoscopic donor nephrectomy: an update.

PURPOSE OF REVIEW: Laparoscopic donor nephrectomy is considered the gold standard for renal donation. In the hands of experienced laparoscopists it provides a safe and equally effective alternative to open nephrectomy, and recipient graft function has been shown to be equivalent regardless of the procurement method utilized. Complication rates and postoperative donor renal function are equivalent to that of open nephrectomy, whereas recovery time is significantly shorter and surgical scars more cosmetic with the laparoscopic approach. RECENT FINDINGS: Advances in preoperative imaging and laparoscopic technique have enabled surgeons to broaden the patient population considered for donor nephrectomy. Improved three-dimensional imaging facilitates operative planning and intraoperative dissection, and the retroperitoneoscopic approach has decreased operative time. Acquisition of laparoscopic skills has also enabled surgeons to perform donor nephrectomies on kidneys that previously would have been considered less desirable for donation (e.g. right-sided or with anomalous vasculature). SUMMARY: End-stage renal disease and the need for renal transplantation continue to be major medical concerns in the United States and worldwide. Advances in donor nephrectomy have reduced the demand for organs by increasing the potential organ pool while limiting risk to donors. As imaging and laparoscopic techniques continue to advance, it is anticipated that minimally invasive donor nephrectomy will continue to evolve. This review summarizes the developments to date.

Costs and Cost Analysis↗

PubMed2004

Laparoscopic radical nephrectomy in obese patients: outcomes and technical considerations.

OBJECTIVES: To review our technique and experience with laparoscopic radical nephrectomy (LRN) in the obese patient population. Obesity has been considered a potential risk factor for poor outcomes in a variety of surgical procedures and has been considered a relative contraindication to laparoscopy. Since 1996, with increased experience and technical modifications, obesity has not been considered a contraindication for laparoscopy at our institution. METHODS: Retrospective data were obtained for all patients who underwent LRN from January 1997 to December 2000. A body mass index (Quetelet's index) greater than 30 was used to define obese patients. Technical modifications included slightly greater insufflation pressures and a lateral shift in trocar sites. The obese laparoscopic group was compared with the nonobese laparoscopic group. RESULTS: Of 101 patients who underwent LRN, 69 were not obese and 32 were obese. No statistically significant differences were observed in any of the analyzed operative data between the nonobese laparoscopic group and obese laparoscopic group, including a mean operative time of 220 and 242 minutes, respectively. Other factors assessed were the time to ambulation, length of hospital stay, conversion rate to an open procedure, and complication rate, which also demonstrated no statistically significant difference. Only one conversion to an open procedure was required in both the obese and the nonobese laparoscopic groups. CONCLUSIONS: With minor technical modifications, LRN can be safely performed in obese patients. Proper trocar site selection and greater insufflation pressures were critical for success. The differences in the intraoperative and postoperative course of LRN in obese and nonobese patients were not statistically significant. Obesity should not be considered a contraindication to laparoscopic nephrectomy.

Aged↗

PubMed2004

Time to recurrent stone formation in patients with bladder or continent reservoir reconstruction: fragmentation versus intact extraction.

PURPOSE: Stone formation following bladder or continent reservoir reconstruction in children is a major source of long-term morbidity. We determine whether the method of stone removal (fragmentation or intact extraction) affected the time to stone recurrence in children after bladder reconstruction. MATERIALS AND METHODS: Medical records from 1993 to 2003 were examined to identify patients with urinary reconstruction subsequently treated for bladder calculi at our institution. Retrospective review of the medical records was performed to determine the type of urinary reconstruction, time to stone recurrence, method of stone removal and length of followup. Kaplan-Meier analysis was performed with each stone episode considered as an individual event. Time to recurrence was measured in months from stone removal to identification of recurrent stones. RESULTS: A total of 60 patients with bladder or continent reservoir reconstructions had undergone 103 stone removal procedures (range 1 to 8 procedures per patient). Patients were rendered stone-free after each procedure. Stones recurred following 42.4% of intact and 43.9% of fragmented extractions at a mean of 27.0 (SD 31.3) and 27.6 (SD 21.8) months, respectively. Kaplan-Meier survival analysis curves for intact and fragmented extractions were not statistically different. CONCLUSIONS: Time to stone recurrence in patients with bladder or continent reservoir reconstruction is not altered by the method of stone removal (fragmented versus intact extraction). Since recurrence remains a frequent problem in children after bladder augmentation and/or reconstruction, use of the least invasive modality should be the initial management recommendation.

Child↗

PubMed2003

Family history of prostate cancer and obesity in relation to high-grade disease and extraprostatic extension in young men with prostate cancer.

BACKGROUND: Little is known about predictors of prostate cancer severity in young men. Therefore, we examined whether family history and obesity influence risk of high-grade disease and extraprostatic extension in men < 55-years old. METHODS: Four hundred ninety-eight men aged < 55 years who had had a radical prostatectomy (1992-1999) by one surgeon were mailed a survey in 2000 to assess family history of PCa and anthropometrics. Body mass index (BMI = kg/m(2)) was calculated as an indicator of obesity. Logistic regression was used to compute odds ratios (OR) for high-grade disease (Gleason score > or = 7) and extraprostatic extension. RESULTS: Of the 363 respondents, 35.8% had at least one first-degree relative with PCa. Men with a family history were younger at surgery than those without a family history (48.8 vs. 50.1 years, P < 0.001). After controlling for age, cigarette smoking, and race/ethnicity, men with an affected father had a lower risk of high-grade disease compared to those without an affected father (OR = 0.42, 95% CI 0.23-0.76). Risk of high-grade disease increased with increasing BMI, especially in men < 50-years old (P-trend = 0.02). Family history and BMI were not clearly associated with extraprostatic extension. CONCLUSIONS: After taking into account a younger age at presentation among men with a family history, young men with a family history of PCa were less likely to have high-grade disease. Obesity may be associated with a poorer histology in young men with PCa, especially in men younger than 50 years of age.

Body Mass Index↗

PubMed2003

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

OBJECTIVES: The 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. METHODS: Renal 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. RESULTS: Using 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. CONCLUSIONS: The 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.

Animals↗

PubMed2003

Association of cigarette smoking with extraprostatic prostate cancer in young men.

PURPOSE: A few recent studies have revealed that cumulative or recent smoking is associated with death from prostate cancer suggesting that smoking may influence progression to more advanced disease. We evaluate the association of cigarette smoking with extraprostatic and/or Gleason sum 7 or greater prostate cancer in young men. MATERIALS AND METHODS: The study included men who underwent radical prostatectomy before age 55 years for prostate cancer between 1992 and 1999. A survey soliciting cigarette smoking history and other exposures was mailed to 498 eligible men. The response rate was 73%. Cases were defined as men with Gleason sum 7 or greater, extraprostatic or Gleason sum 7 or greater/extraprostatic disease based on pathologic analysis. All remaining participants were considered noncases for each case definition. We used logistic regression modeling to estimate the odds ratio (OR) for Gleason sum 7 or greater, extraprostatic and Gleason sum 7 or greater/extraprostatic disease with cigarette smoking. RESULTS: Of the 352 respondents with a cigarette smoking history 5.4% were current smokers and 44.6% were former smokers at the time of surgery. The odds ratios of extraprostatic and Gleason sum 7 or greater/extraprostatic disease were 3.85 (95% CI 1.44-10.33) and 3.17 (95% CI = 1.13-8.85), respectively, for current smokers compared to men who never smoked. Evidence of an association of smoking with Gleason sum 7 or greater disease was limited. Risk of extraprostatic (p = 0.005) and Gleason sum 7 or greater/extraprostatic (p = 0.003) disease increased with increasing cumulative pack-years smoked. Higher cumulative smoking in the 10 years before surgery was associated with an increased risk of extraprostatic (p = 0.004) and Gleason sum 7 or greater/extraprostatic (p = 0.005) disease. CONCLUSIONS: Cigarette smoking may influence the risk of extraprostatic prostate cancer in young men.

Age Factors↗

PubMed2002

Focused ultrasound ablation of the epididymis with use of thermal measurements in a canine model.

OBJECTIVE: To explore the epididymis as an alternative anatomical target to the vas deferens for noninvasive male sterilization using therapeutic focused ultrasound. DESIGN: Controlled preclinical study. SETTING: Canine animal model in an academic research environment. PATIENT(S): Four healthy male mongrel dogs (30-35 kg). INTERVENTION(S): A transducer mounted on a plastic clip delivered ultrasound energy to the canine epididymis. Thermocouples placed transcutaneously into the epididymis, intradermally, and on the skin surface recorded temperatures during ablation with a wide range of acoustic powers and sonication times (control, 3 W/120 s, 5 W/90 s, 7 W/60 s). MAIN OUTCOME MEASURE(S): Thermocouple temperature measurements determined the optimal range of ablation parameters that produced successful thermal occlusion of the epididymis without adverse effects (e.g., skin burns, testicular injury). RESULT(S): A large "therapeutic window" was determined (power = 3-7 W, time = 20-120 seconds) over which noninvasive thermal occlusion of the epididymis can be achieved. Thermal occlusion rates were higher, and complications lower, than found previously with vas deferens ablation. CONCLUSION(S): The epididymis represents a larger and easier target than the vas deferens for performing noninvasive male sterilization using focused ultrasound. Long-term azoospermia studies will be necessary to confirm permanent sterilization with this technique.

Animals↗

PubMed2002

High-intensity focused ultrasound ablation of the epididymis in a canine model: a potential alternative to vasectomy.

BACKGROUND AND PURPOSE: High-intensity focused ultrasound (HIFU) is a noninvasive technology capable of inducing thermal coagulative necrosis of subsurface structures without injuring intervening tissues. We have previously reported on the feasibility of HIFU vasectomy in a canine model. In this study, we evaluated the feasibility of HIFU ablation of the canine epididymis as an alternative to vasectomy. The epididymis may be a better target than the vas deferens because it is larger, more easily positioned in the HIFU focal zone, and more susceptible to occlusive injury at lower energy levels, thus reducing collateral damage. MATERIALS AND METHODS: A hand-held HIFU clamp was used to grasp the epididymides of anesthetized dogs (eight surgically exposed and six grasped transcutaneously). An ultrasound transducer in the clamp focused energy on a 1 x 3 x 8-mm target zone centered between the clamp jaws. Ultrasonic energy (6-19 W) was delivered to this target zone for various times (16-150 seconds). The vas, epididymis, and testis were harvested for histologic examination 2 weeks after ablation. RESULTS: Seven of the eight epididymides ablated after surgical exposure demonstrated histologic findings associated with occlusion (fibrosis, hemorrhage, and proximal duct dilatation). Five of the six epididymides ablated transcutaneously also demonstrated histologic evidence of occlusion. Skin burns were evident overlying three epididymides, and one testicular injury was noted adjacent to an ablated region of the epididymis. CONCLUSION: High-intensity focused ultrasound ablation of the epididymis causes injury and histologic changes associated with epididymal occlusion. Further investigations are under way to optimize ablation parameters and to confirm azoospermia with ejaculate studies. Refinement of this technology may provide a rapid noninvasive alternative to conventional vasectomy.

Animals↗

PubMed2002

Robotic percutaneous access to the kidney: comparison with standard manual access.

PURPOSE: To evaluate the efficiency, accuracy, and safety of robotic percutaneous access to the kidney (PAKY) for percutaneous nephrolithotomy in comparison with conventional manual techniques. MATERIALS AND METHODS: We compared the intraoperative access variables (number of access attempts, time to successful access, estimated blood loss, complications) of 23 patients who underwent robotic PAKY with the remote center of motion device (PAKY-RCM) with the same data from a contemporaneous series of 23 patients who underwent conventional manual percutaneous access to the kidney. The PAKY-RCM incorporates a robotic arm and a friction transmission with axial loading system to accurately position and insert a standard 18-gauge needle percutaneously into the kidney. The blood loss during percutaneous access was estimated on a four-point scale (1 = minimal to 4 = large). The color of effluent urine was graded on a four-point scale (1 = clear to 4 = red). RESULTS: The mean target calix width was 13.5 +/- 9.2 mm in the robotic group and 12.2 +/- 4.5 mm in the manual group (P = 0.57). When comparing PAKY-RCM with standard manual techniques, the mean number of attempts was 2.2 +/- 1.6 v 3.2 +/- 2.5 (P = 0.14), time to access was 10.4 +/- 6.5 minutes v 15.1 +/- 8.8 minutes (P = 0.06), estimated blood loss score was 1.3 +/- 0.49 v 1.7 +/- 0.66 (P = 0.14), and color of effluent urine following access was 2.0 +/- 0.90 v 2.1 +/- 0.7 (P = 0.82). The PAKY-RCM was successful in obtaining access in 87% (20 of 23) of cases. The other three patients (13%) required conversion to manual techniques. There were no major intraoperative complications in either group. CONCLUSIONS: Robotic PAKY is a feasible, safe, and efficacious method of obtaining renal access for nephrolithotomy. The number of attempts and time to access were comparable to those of standard manual percutaneous access techniques. These findings provide the groundwork for the development of a completely automated robot-assisted percutaneous renal access device.

Blood Loss, Surgical↗

PubMed2002

Local hemostasis during laparoscopic partial nephrectomy using biodegradable hydrogels: initial porcine results.

BACKGROUND AND PURPOSE: Despite the advance of laparoscopic partial nephrectomy, significant technical limitations remain with regard to control of bleeding and closure of the collecting system. An attractive approach on the horizon for local hemostatic and wound control is the use of local tissue sealants. To date, sealants remain largely derived from natural biologic products and are difficult to apply laparoscopically with precise local control. In this study, we examined the novel strategy of forming occlusive tissue-adherent hydrogels utilizing a synthetic biodegradable polyethylene glycol-lactide copolymer (PEG-lactide) as an in situ occlusive barrier for hemostasis and wound control. Specifically, the objects of this study were to determine if PEG-lactide hydrogels could be formed intraperitoneally on renal tissue, to test the adhesiveness of the hydrogels to injured renal parenchyma, and to evaluate the ability of adherent hydrogel barriers to limit renal parenchymal bleeding and collecting system leakage following renal pole amputation or wedge excision. MATERIALS AND METHODS: Five kidneys from three female pigs were used in a nonsurvival study. A standardized model for laparoscopic partial nephrectomy was created by performing wedge excision or polar amputation under vascular control using a laparoscopic Satinsky clamp. Bleeding briskness following injury was assessed utilizing a scoring system and free blood quantitated comparing a conventional "clamp and wait" strategy with an adherent hydrogel strategy. For the hydrogel group, PEG-lactide hydrogel primer and macromer were applied through laparoscopic ports. The hydrogel was polymerized using a xenon light source, and the pedicle clamp was released to observe for bleeding. A subsequent opposite polar injury was created to confirm renal perfusion and the sites were compared. The kidneys were removed, and the adhesion of the hydrogel to the renal parenchyma was examined. RESULTS: The PEG-lactide macromer was effectively applied to five kidneys following partial nephrectomy. In all cases, successful intraperitoneal in situ polymerization was achieved, with resultant hydrogel formation. Polymeric hydrogel adhesion to the cut renal parenchyma was assessed semiquantitatively following vigorous cyclic washing. In all cases, polymer gels remained adherent without any evidence of peeling, delamination, or separation from the underlying tissue surface. In the control group, the mean bleeding score was 2.63 +/- 0.48 v 0.00 +/- 0.00 in the gel-treated group (P < 0.001). Blood loss in the control group was 56 +/- 5 ml v 0.00 +/- 0.00 in the gel-treated group (P < 0.001). In an ex vivo retrograde ureteral perfusion, no leakage was observed at pressure as high as 100 mm Hg. CONCLUSIONS: In this feasibility study, a biodegradable PEG-lactide polymer system photopolymerized rapidly in situ on exposed renal parenchymal surfaces, forming adherent hydrogel barriers. When applied during vascular clamping, an adequate physical bond and patch-like cap was created to prevent bleeding at physiologic renal perfusion pressures. Use of locally applied occlusive hydrogels holds promise for hemostasis and local wound control during laparoscopic urologic procedures.

Absorbable Implants↗

PubMed2002

Measurement of needle-tip bioimpedance to facilitate percutaneous access of the urinary and biliary systems: first assessment of an experimental system.

RATIONALE AND OBJECTIVES: Percutaneous access to the renal collecting system or biliary system is most frequently performed under image guidance. However, current techniques lack a feedback mechanism to help confirm successful access. A percutaneous needle system has been developed consisting of a modified 18-gauge percutaneous access needle that measures tissue impedance at its needle tip. Initial results in utilizing this novel system to determine successful access into dilated kidney and gall bladder specimens are reported. METHODS: Impedance measurements were recorded as the needle was precisely advanced through ex vivo kidney and liver/gall bladder specimens. In an anesthetized porcine model, impedance values were recorded with laparoscopic visualization as the needle was advanced percutaneously through abdominal wall, liver, and into gall bladder. RESULTS: A characteristic, reproducible drop in impedance was noted with successful entry into ex vivo distended kidney and gall bladder specimens. This feature was also noted during in vivo percutaneous cholecystostomy. CONCLUSIONS: A measurable, characteristic drop in tissue impedance signifies successful entry into the urinary and biliary systems. This impedance needle system may facilitate current percutaneous access techniques.

Animals↗

PubMed2002

High intensity focused ultrasound ablation of the vas deferens in a canine model.

PURPOSE: High intensity focused ultrasound is an ablative technology capable of producing thermal coagulative necrosis of sub-surface structures without injuring intervening tissues. We assessed the feasibility of using high intensity focused ultrasound to produce occlusion of the canine vas deferens. MATERIALS AND METHODS: A high intensity focused ultrasound transducer was incorporated into a hand held clip specially designed to grasp the vas deferens transcutaneously. Slots within the jaws of the clip ensured that the vas deferens and high intensity focused ultrasound target zone were properly co-located. We ablated 10 vasa using a range of power and time parameters. At 2 weeks after ablation each vas, epididymis and testis was surgically harvested en bloc. Retrograde vasography was performed to assess vasal occlusion, followed by pathological analysis. RESULTS: High intensity focused ultrasound occlusion of the vas deferens was confirmed in 4 specimens ablated with parameters at the upper end of the parameter range, 2 of the 2 ablated with 7 W. for 60 seconds and 2 of the 4 ablated with 7 W. for 30 seconds. Histological injury was noted in 8 of the 10 ablated specimens. Skin burns that developed over 4 of the targeted vasa were conservatively managed. Bilateral sham procedures in a control dog resulted in patent vasa and no associated skin burns. CONCLUSIONS: We demonstrated the feasibility of noninvasive, transcutaneous high intensity focused ultrasound occlusion of the vas deferens with ablation powers at the upper end of the tested range, that is 7 W. Modifications of the hand held clip and optimization of ablation parameters would likely improve the success rate of this procedure. Refinement of this technology may provide a rapid noninvasive alternative to conventional vasectomy.

Animals↗