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Biomedical subjects

David I Lee

Publications and source records attributed to David I Lee.

27 records · Page 2Linked to original sources
PubMed2003

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.

Humans↗
PubMed2003

Retroperitoneal laparoscopic cryoablation of small renal tumors: intermediate results.

OBJECTIVES: To present our experience with laparoscopic renal cryoablation with up to 3 years of follow-up. Laparoscopic renal cryoablation remains a viable option for the treatment of small peripheral renal masses in patients with significant comorbidities. Although partial nephrectomy has been shown to be a safe and reliable method of renal parenchymal preservation, laparoscopic cryoablation still requires longer term data to prove its efficacy. METHODS: Twenty patients with small renal masses (1.4 to 4.5 cm) underwent laparoscopic renal cryosurgery at our institution. A retroperitoneal laparoscopic approach was used to expose the kidney. Intraoperative ultrasound guidance was used to localize the lesions and monitor iceball formation. A double-freeze technique was used. Needle biopsies of solid masses were performed intraoperatively. RESULTS: Renal biopsies revealed renal cell carcinoma in 11 of the 20 patients. Of these 11 patients, none had evidence of recurrent disease at last follow-up, and follow-up scans showed no enhancement of any lesions. Of the 8 patients with follow-up of 2 years or greater, 4 had complete resolution of the renal lesions. The remainder had lesions that were reduced and stable in size. Complications included surgical re-exploration to evaluate pancreatic injury in 1 patient and failure to ablate a lesion in another. CONCLUSIONS: Laparoscopic renal cryoablation appears to be an effective tool for ablation of small renal lesions. A moderate length of follow-up continues to demonstrate efficacy because no patients had growth of treated pathologic lesions or developed metastasis to date. Continued maturation of data is necessary to determine the long-term efficacy.

Adult↗
PubMed2003

Characterization of intrapelvic pressure during ureteropyeloscopy with ureteral access sheaths.

OBJECTIVES: To evaluate the impact of the ureteral access sheath on intrarenal pressures during flexible ureteroscopy in light of the recent resurgence in their use. As such, using human cadaveric kidneys, we studied changes in intrarenal pressure in response to continuous irrigation at different pressures with and without access sheaths of various sizes and lengths. METHODS: This study was performed using seven cadaveric kidneys. In three kidneys the study was done in situ with a 7.5F flexible ureteroscope (URS) passed by itself and then passed through a 10/12F sheath (35 and 55 cm in length), whereas, in four kidneys, due to narrowing of the intramural ureter, the study was done ex vivo using the unsheathed URS and then passing the 7.5F flexible URS via the 10/12F, 12/14F, and 14/16F sheaths (all 35 cm in length). A 10F Cope loop pyelostomy was placed to measure intrapelvic renal pressure. Three sets of 3-minute readings (ie, flow and intrarenal pressure) were taken with the tip of the URS at the distal ureter, middle ureter, and renal pelvis (just above the ureteropelvic junction); the entire process was done at three different irrigant pressure settings: 50, 100, and 200 cm H(2)O. Irrigant flow and intrarenal pressures were measured at all three settings using the URS passed without a sheath and then with the URS passed through the various sheaths positioned at the distal ureter, middle ureter, and renal pelvis. RESULTS: With all of the sheaths, intrapelvic pressure remained low (less than 30 cm H(2)O), and there was a 35% to 80% increase in irrigant flow versus the control unsheathed URS. With the sheath in place, the majority of the irrigant drained alongside the URS and out the sheath. Flow and pressure with the 12/14F sheath were equivalent to the 14/16F sheath. CONCLUSIONS: The 12/14F access sheath provides for maximum flow of irrigant while maintaining a low intrarenal pelvic pressure. Even with an irrigation pressure of 200 cm H(2)O, renal pelvic pressure remained below 20 cm H(2)O.

Equipment Design↗
PubMed2003

Evaluation of overall costs of currently available small flexible ureteroscopes.

OBJECTIVES: To perform a meta-analysis of the currently available data regarding the durability of flexible ureteroscopes to establish cost estimates for the purchase and use of five currently available, smaller than 9F, ureteroscopes. Healthcare costs have become increasingly germane to the determination of disease management strategies. Improved ureteroscope technology has expanded the role of these instruments. However, the initial purchase costs and high maintenance costs have become problematic with these fragile instruments. METHODS: Ureteroscope durability data on the Storz 11274AA, Olympus URF-P3, Wolf 7325.172, ACMI AUR-7, and ACMI DUR-8 were collected from three prior studies. Combining the durability data and cost data regarding the initial purchase price and maintenance costs of these instruments, we calculated the overall costs associated with the use of each of the ureteroscopes for 25, 50, 75, and 100 cases during the first year (warranties included) and with subsequent use. RESULTS: The variability in the costs associated with the use of the currently available smaller than 9F ureteroscopes was significant. The initial instrument purchase price, durability, repair costs, and associated warranties all contributed to large discrepancies in the cost of performing ureteroscopy. In this model, during the first year of ownership, the projected cost of performing 100 ureteroscopic cases varied by a difference of 95% depending on the ureteroscope used. CONCLUSIONS: Physicians and institutions that perform ureteroscopy should strongly consider the purchase price, durability, repair cost, and associated warranties before the purchase of small flexible ureteroscopes.

Costs and Cost Analysis↗
PubMed2003

Novel approach to minimizing trocar sites during challenging hand-assisted laparoscopic surgery utilizing the Gelport: trans-gel instrument insertion and utilization.

PURPOSE: We present a novel technique for modified application of a hand-assist device, the Gelport (Applied Medical Resources, Rancho Santa Margarita, CA), which uses a gel for intra-abdominal access. MATERIALS AND METHODS: A 53-year-old woman with a history of rectal cancer treated by abdominoperineal resection, ileostomy, subsequent reanastomosis, chemotherapy, and radiation presented with a 6-cm upper-pole left renal mass. Staging was negative, and a CT scan showed no evidence of lymphadenopathy or renal vein involvement. The patient elected to undergo a hand-assisted laparoscopic radical nephrectomy. Numerous intra-abdominal adhesions were encountered during initial periumbilical hand port placement. The initial adhesions were taken down in an open fashion; however, the proposed trocar sites still could not be exposed. The Gelport was placed, and a laparoscope was passed directly through the established central opening and the gel. A working instrument was then passed through the gel itself, allowing adhesiolysis under direct laparoscopic vision. RESULTS: The nephrectomy was completed laparoscopically in 4 hours and 15 minutes with lysis of adhesion occupying 90 minutes of the operative time. The estimated blood loss was 150 mL. Despite the technical difficulty of the case, the procedure was completed laparoscopically with two standard 12-mm trocars and a 5-mm lateral retraction trocar. CONCLUSION: The Gelport permits simultaneous insertion of the surgeon's hand and a working laparoscopic instrument. This allows for maximally efficient utilization of the incision made for hand-assist device placement and may minimize the need for additional trocars during challenging laparoscopic cases.

Female↗
PubMed2003

Laparoscopic cyst decortication in autosomal dominant polycystic kidney disease: impact on pain, hypertension, and renal function.

BACKGROUND AND PURPOSE: In patients with autosomal dominant polycystic kidney disease (ADPKD), laparoscopic cyst decortication (LCD) has been proposed as a means to relieve chronic cyst-related pain. We present our 7-year experience with LCD for ADPKD with regard to pain relief, hypertension, and renal function. PATIENTS AND METHODS: Between August 1994 and February 2001, 29 ADPKD patients with chronic pain (N=29), hypertension (N=21), and renal insufficiency (N=10) underwent 35 LCD procedures. Every detectable cyst within 2 mm of the renal surface was treated. Pain relief was assessed using a pain analog scale; relative pain relief (RPR) equaled (preoperative pain score) - (postoperative pain score)/(preoperative pain score). Hypertension was evaluated using the antihypertensive therapeutic index (ATI): [(dose of blood pressure medication 1/max dose 1) + (dose med 2/max dose 2) + etc.] x 10. Renal function was assessed using the Cockcroft and Gault formula for creatinine clearance. RESULTS: The mean operating room time was 4.9 hours (range 2.6-6.6 hours) with no conversions to open surgery. An average of 220 cysts (range 4-692) were treated per patient. The mean follow-up was 32.3 months (range 6-72 months). The RPR was 58%, 47%, and 63% at 12, 24, and 36 months, respectively. At 12, 24, and 36 months, 73%, 52%, and 81% of patients, respectively, noted >50% improvement in their pain compared with the preoperative situation. Five patients became normotensive, and patients improved their ATI by an average of 49% (range 11%-93%). However, six patients had worsening hypertension, with an ATI increase averaging 53% (range 11%-122%), and one patient who was not hypertensive preoperatively has since developed hypertension. The creatinine clearance changed +4%, +7%, and -2% at 12, 24, and 36 months, respectively. Only one patient had a >20% increase in creatinine clearance. The only patients with a >20% decrease in creatinine clearance were those who had a creatinine clearance <30 mg/dL preoperatively (average decrease 34% [range 20%-51%]). CONCLUSIONS: For ADPKD patients with debilitating pain, extensive LCD can provide durable relief. In the majority of patients with pain and hypertension, a marked improvement in blood pressure also occurs. Cyst decortication was not associated with worsening renal function; indeed, renal function remained largely unchanged over the 3-year follow-up period.

Adult↗
PubMed2002

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.

Catheterization↗
PubMed2002

Bare naked baskets: ureteroscope deflection and flow characteristics with intact and disassembled ureteroscopic nitinol stone baskets.

PURPOSE: Lower pole renal access during flexible ureterorenoscopy is often limited by the active deflection capabilities of the ureteroscope. Deterioration in the deflection and flow capabilities of ureteroscopes occurs with the passage of instrumentation through the working channel. We performed in vitro evaluation of a novel technique using unsheathed nitinol baskets to minimize the deterioration in deflection and maximize the irrigant flow associated with instrument passage through the working channel during flexible ureterorenoscopy. MATERIALS AND METHODS: Alterations in the irrigant flow and active deflection of 4 ureteroscopes from different manufacturers were evaluated. Each ureteroscope was evaluated with an empty working channel, and then with sheathed and unsheathed 2.2, 3 and 3.2Fr (Cook Urological, Inc., Indianapolis, Indiana), 2.4 and 3Fr (Microvasive Urology, Natick, Massachusetts) nitinol baskets in the working channel. RESULTS: With all baskets tested and in all ureteroscopes the deterioration in active deflection and irrigant flow was improved with the unsheathed baskets. The disassembled basket within the working channel allowed an additional 15 to 20 degrees of active deflection. In addition, the disassembled basket allowed for a 2 to 30-fold increase in irrigant flow compared with an intact basket. CONCLUSIONS: The combination of improved deflection and irrigant flow with this technique may improve ureteroscopic access to lower pole renal calculi.

Alloys↗