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Biomedical subjects

David I Lee

Publications and source records attributed to David I Lee.

At least 19 recordsLinked to original sources
PubMed2005

Effect of urine specific gravity on effectiveness of shockwave lithotripsy.

PURPOSE: To determine the effect of urine specific gravity (SG) and radiographic contrast medium on the efficiency of extracorporeal shockwave lithotripsy (SWL) fragmentation using a previously published in vitro model. MATERIALS AND METHODS: Artificial kidney stones (BegoStone [BEGO USA, Smithfield, RI]) of a standard size (10 x 10 mm) and weight (mean 1.90 g; range 1.89-1.91 g) were randomly allotted to one of four test media with differing SG: group 1: synthetic urine, SG 1.003; group 2: synthetic urine, SG 1.040; group 3: 50% radiographic contrast (Cysto-Conray II, Mallinckrodt Inc., Hazelwood, MO), 50% synthetic urine, SG 1.069; and group 4: 100% contrast, SG 1.121. The stones were placed in cups made of 2.2-mm screen mesh and exposed to 500 shockwaves at 20 KV from a spark-gap lithotripter (Econolith 2000; Medispec, Germantown, MD). The stone fragmentation rate (i.e., percent fragmentation) was determined by dividing the dry residual stone weight by the prelithotripsy dry weight (X 100). RESULTS: The mean fragmentation rate for the four groups was 31.7%, 37.6%, 31.8%, and 27.2%, respectively. Statistical significance was not achieved (P = 0.1). CONCLUSION: Stone breakage tends to be more effective when urine SG is about 1.040 than at higher or lower values. Hence, the recommendation for an overnight fast prior to SWL is well founded. Introduction of contrast medium may inhibit stone breakage because it increases the specific gravity.

Humans↗
PubMed2005

Impact of a double-pigtail stent on ureteral peristalsis in the porcine model: initial studies using a novel implantable magnetic sensor.

BACKGROUND AND PURPOSE: The effect of stents on ureteral peristalsis in vivo is not entirely clear. We sought to develop a minimally invasive method for its study. MATERIALS AND METHODS: In female domestic pigs, electrical potentials from the ureter were measured by bipolar steel-wire electromyography electrodes delivered laparoscopically. Mechanical movement was measured by giant magneto resistive sensors mounted on custom-made aluminum strips. After baseline values were obtained, the animals were randomized to receive silicone or polyurethane stents, and ureteral peristalsis was measured for 8 hours acutely and for 4 hours 1 week later. RESULTS: Implantation of the devices took an average of 30 minutes. A consistent correlation was found between laparoscopically observed peristaltic waves and the peristalsis detected by the two measuring devices. The devices themselves did not affect peristalsis. Stent insertion increased peristaltic activity initially but later reduced or stopped it. There was no difference in the effects of the two types of stents. CONCLUSIONS: The new technique permits close monitoring of ureteral peristalsis in vivo. Smaller stents appear to have less immediate effect than larger ones, but all type of stents tested eventually caused aperistalsis.

Animals↗
PubMed2005

What happens to hemostatic agents in contact with urine? An in vitro study.

BACKGROUND AND PURPOSE: As the indications for topical hemostatic agents increase in urology, the question arises: what happens to these agents when they enter the urinary collecting system? To answer this question, we performed a series of in-vitro experiments mixing three hemostatic agents with normal and sanguineous urine. MATERIALS AND METHODS: Four commercially available topical hemostatic products: oxidized regenerated cellulose (Surgicel; Ethicon, Somerville, NJ), fibrin sealant (Tisseel VH Kit; Baxter Health Care Corporation, Irvine, CA), gelatin matrix hemostatic sealant (FloSeal; Baxter Health Care), and polyethylene glycol (CoSeal; Cohesion Technologies, Palo Alto, CA) were studied. Human urine (10 mL) was added to samples of each substance; this was done in triplicate. The 12 sample tubes were then capped and placed on a tube shaker at slow speed and 37 degrees C. Observations regarding consistency of the material were made at 6, 12, 24, 48, 72, 96, and 120 hours (5 days). Gelatin matrix hemostatic sealant was further tested in urine with various amounts of blood or blood clot; observations were again recorded out to 5 days. RESULTS: Surgicel maintained its solid form when it initially came in contact with urine, but over a period of 5 days, it transformed into a mucoid substance with visible free-floating fibers. It did not dissolve completely in urine within 5 days. Gelatin matrix was immediately transformed by urine into a fine colloidal suspension that did not change over the 5 days of the study. Fibrin glue, after mixing of the two components (fibrinogen and thrombin) directly in the urine, and polyethylene glycol immediately formed a solid clot at the bottom of the test tube on contact with the urine. When the mixture of fibrin sealant was allowed to form for 15 minutes and then added to urine, it again maintained a solid form. After 72 hours, the fibrin glue became a semisolid gelatinous plug. On analysis at 5 days, the fibrin sealant clot had transformed into a cohesive mucoid gel, and the polyethylene glycol clot had not changed. The gelatin matrix hemostatic sealant, when in contact with blood or blood clot, appeared to either become part of a clot or to remain in a colloidal suspension. At 5 days, all clots had dissolved to fine particulate suspensions, and the gelatin matrix appeared as a fine suspension. CONCLUSION: Fibrin glue and oxidized regenerated cellulose maintain a solid form when initially placed in direct contact with urine and then assume a semisolid gelatinous state, which is still present at 5 days. Polyethylene glycol forms a solid clot initially and does not change after 5 days. Only hemostatic gelatin matrix remained as a fine particulate suspension in both normal and sanguineous urine. The implications of these findings with regard to sealing the renal parenchyma or small violations of the collecting system after percutaneous or laparoscopic surgery await in-vivo testing.

Blood Loss, Surgical↗
PubMed2005

Fibrin glue-oxidized cellulose sandwich for laparoscopic wedge resection of small renal lesions.

PURPOSE: We present our experience with standard laparoscopic wedge resection of small renal tumors using a fibrin glue-oxidized cellulose sandwich for hemostasis. MATERIALS AND METHODS: From May 2002 to December 2003, 15 patients underwent laparoscopic wedge resection for a total of 15 nonhilar renal masses. Renal hilar clamping was performed in 1 patient and no sutures were placed. We used ultrasonic shears and an argon beam coagulator to resect and then coagulate the tumor bed. Tisseel (Baxter Corp., Deerfield, Illinois) was applied to the resection bed, followed by a layer of oxidized, regenerated cellulose (Surgicel, Ethicon, Somerville, New Jersey) and a final layer of Tisseel. RESULTS: Mean preoperative tumor size was 2.2 x 2.2 x 2.1 cm. Lesions were subdivided based on the percent of the lesion that extended beyond the renal parenchymal border on computerized tomography as exophytic-greater than 60% in 6 cases, endophytic-less than 40% in 4 and mesophytic-40% to 60% in 5. Mean operative time was 3.8 hours (range 3 to 5). Mean blood loss was 108 ml (range 20 to 300). No patient required blood transfusion. There was no significant difference in blood loss or change in creatinine among the endophytic, exophytic and mesophytic groups (150, 121 and 93 ml, and 0.03, 0.07 and 0.04 mg/dl, respectively). Margin status was negative in all cases (mean thickness 3.2 mm). Average hospital stay and time to the resumption of oral intake were 2.7 and 1.4 days, respectively. CONCLUSIONS: Small exophytic or mesophytic renal lesions can be safely excised laparoscopically without vessel clamping. Excellent hemostasis was achieved in each case with the newer hemostatic agents.

Aged↗
PubMed2004

Robot-assisted versus open radical prostatectomy: a comparison of one surgeon's outcomes.

OBJECTIVES: To compare internally one surgeon's standard open radical prostatectomy (RP) and robot-assisted laparoscopic RP (RLP) results. RLP, like standard laparoscopic RP, ultimately needs to produce similar or improved results compared with standard RP techniques. Little information comparing RLP with standard RP exists. METHODS: As an internal control, we selected the last 60 standard RPs performed by one surgeon (T.A.) before initiating RLPs. For the RLP group, we selected cases 46 to 105 (n = 60) after the learning curve had adequately matured. We compared the clinical characteristics, perioperative results, and early clinical outcomes. RESULTS: The study and control groups had similar clinical characteristics (age, body size, preoperative prostate-specific antigen level, clinical stage, and Gleason score). No statistically significant differences were found between groups for prostate size, pT stage, Gleason score, or margin status (16.7% versus 20%; P = nonsignificant). The RLP group had a statistically significant advantage for estimated blood loss (103 versus 418 mL), postoperative hemoglobin change (1.6 versus 3.3 mg/dL), and hospital stay (1.02 versus 2.2 days). Complete continence (0 pads) at 3 months of follow-up and the rate of postoperative complications were similar for the RLP and RP groups (76% versus 75% and 6.7% versus 10%, respectively). CONCLUSIONS: We present the results of RLP and RP performed by one surgeon. With only a 100-case experience, RLP had oncologic and urinary outcomes that were at least equal to those after RP. RLP offers the benefits of minimally invasive surgery and does not compromise clinical or pathologic outcomes.

Adult↗
PubMed2004

Robotic laparoscopic radical prostatectomy with a single assistant.

INTRODUCTION: As experience with robot-assisted laparoscopic radical prostatectomy (rLRP) grows, the importance of the role of the assistant cannot be overstated. Key elements of the operation, dependent on the assistant, have not been reported. The focus of this report was to describe the key elements, which include positioning of the patient and assistant port sites, appropriate equipment, and the assistant-dependent steps of the procedure. TECHNICAL CONSIDERATIONS: During the course of the initial 100 cases, we reviewed the patient and port site positioning and reviewed the videotapes to identify key elements of the assistant's role that facilitate rLRP. We identified three important elements pertaining to patient positioning. In contrast to standard port site recommendations, we found that dominant and nondominant handedness dictate the assistant port site locations. Finally, we identified specific steps of the procedure that require the assistant to have laparoscopic skills necessary for the console surgeon to dissect the bladder neck, seminal vesicles, rectum, and neurovascular bundles. CONCLUSIONS: The assistant in rLRP is critical to the success of rLRP, especially in the learning phases. Right or left-handed dominance determines on which side the assistant should be positioned. In contrast to the console surgeon, the assistant should have intermediate to advanced laparoscopic skills.

Dissection↗
PubMed2004

Robotic radical prostatectomy: a technique to reduce pT2 positive margins.

OBJECTIVES: To describe a technique using the da Vinci robotic system that enhances one's ability to visualize and dissect the apex and reduce surgical margins. An important outcome of radical prostatectomy is the reduction of iatrogenic positive margins in organ-confined prostate cancer. TECHNICAL CONSIDERATIONS: The clinical data of our first 140 consecutive robot-assisted radical prostatectomies were divided into two groups: group 1, cases 1 to 50; and group 2, cases 51 to 140. After reviewing the surgical margin data and appropriate video clips of our initial 50 patients, we altered our technique. Initially, we had used two sutures to control the dorsal venous complex (DVC), one proximally and distally. The prostate was freed, and, finally, the DVC and urethra were divided. However, a bundle of fat obscured the apex, leading to positive apical margins. We developed the following method. First, we removed all of the fat overlying the DVC and prostate. Second, we divided the puboprostatic ligaments and dissected the levator fibers to expose and increase the DVC length fully. Finally, we stapled and divided the DVC using a vascular stapler. RESULTS: The two groups were clinically comparable. Overall, the pathologic margin rate improved from 36% in group 1 to 16.7% in group 2. In group 1, 9 (27.3%) of 33 pT2 tumors had positive margins versus 3 (4.7%) of 64 pT2 tumors in group 2 (P = 0.003). CONCLUSIONS: The data demonstrate that this change in technique for robotic prostatectomy resulted in a more defined apical dissection and a statistically significant reduction in positive margins in patients with organ-confined disease.

Adult↗
PubMed2004

Ureteroscopes: flexible, rigid, and semirigid.

Since its introduction, the ureteroscope has undergone significant improvements. Using the currently available rigid, semirigid, and flexible ureteroscopes and working instruments, urologists can diagnose and treat lesions throughout the upper urinary tract. Over the past 25 years, the ureteroscope in combination with shock wave lithotripsy has transformed the diagnosis and treatment of more than 90% of upper urinary tract pathology from an open to an endourologic procedure. With endoscope manufacturers continually incorporating new technology into their ureteroscopes, future models will undoubtedly provide better optics, increased durability, and improved capabilities, resulting in greater success when urologists perform endoscopic forays into the upper urinary tract.

Equipment Design↗
PubMed2004

Hand-assisted laparoscopic nephrectomy in autosomal dominant polycystic kidney disease.

BACKGROUND: Among patients with renal insufficiency secondary to autosomal dominant polycystic kidney disease (ADPKD), the onset of refractory urinary infection, hypertension, pain, or hematuria often necessitates a nephrectomy. However, the huge size of these kidneys makes a standard laparoscopic approach difficult, and the increased fragility of these patients makes an open nephrectomy risky. A compromise position has been found in the realm of hand-assisted laparoscopic techniques, especially for patients in need of a bilateral nephrectomy. TECHNIQUE: Hand-assisted laparoscopic nephrectomy (HALN) is performed via a hand-assist device placed in the midline. A subxiphoid midline port and a midclavicular subcostal port are placed on the ipsilateral side. The right hand is inserted for left nephrectomy and the left hand for a right nephrectomy. The laparoscope is introduced into the subxiphoid port, and the surgeon's primary working instrument is passed via the midclavicular port. Occasionally, it is helpful to place a 5-mm subcostal port in the midaxillary line to aid in retracting the kidney. Once the kidney is devascularized, it is removed via the 7- to 8-cm hand-assist incision; drainage of cysts may be necessary during extraction to reduce the kidney size so that it can be withdrawn. If a bilateral approach is to be done, then after the first nephrectomy, the lateral 5-mm port is closed, and the table is rolled such that the contralateral side is elevated about 30 degrees to 45 degrees; a subcostal midclavicular 12-mm port is placed, and, if needed, a 5-mm port is inserted subcostally in the midaxillary line for renal retraction. RESULTS: Seven bilateral hand-assisted laparoscopic nephrectomy cases have been reported. In two reports, the mean operating times were 4.8 and 5.5 hours. The mean estimated blood loss was <350 mL. CONCLUSION: The hand-assisted laparoscopic approach makes both unilateral and bilateral nephrectomy feasible in ADPKD patients with acceptable morbidity.

Humans↗
PubMed2004

One-knot pyeloplasty.

Laparoscopic pyeloplasty represents one of the more advanced reconstructive procedures for the urologist. While early reports were replete with long operative times, there have been several changes that have added to the efficiency of the procedure. In our practice, we have found three changes to be of greatest value: (1) an upper-midline port placement; (2) use of a continuous suture for the anastomosis with a double-armed, knotted suture; and (3) antegrade stent placement.

Humans↗
PubMed2004

Intraoperative catheter management during laparoscopic excision of a giant bladder diverticulum.

BACKGROUND: Massive bladder diverticula present a technical challenge to the laparoscopic surgeon. We describe a laparoscopic approach to transperitoneal diverticulectomy, using a specific catheter arrangement to allow excellent control of the various portions of the procedure. METHODS: A 49-year-old male with longstanding frequency was diagnosed with a 1000 cc bladder diverticulum and bladder neck outlet obstruction. Laparoscopic transperitoneal diverticulectomy was performed using a triple catheter arrangement: endoscopic placement of a Councill catheter in the diverticulum, fluoroscopic positioning of an occlusion balloon catheter in the renal pelvis, and placement of a Cope loop suprapubic tube. Additionally, a transurethral incision of the prostate was performed. RESULTS: The procedure was completed laparoscopically using a four port transperitoneal approach. During the procedure, the diverticulum could be filled and emptied as needed; the catheter across the diverticular neck facilitated subsequent closure of the bladder wall defect. The diverticulum was completely excised. The remaining defect in the bladder was then closed in 2 layers. The patient was discharged on postoperative day 3. CONCLUSION: Careful planning and arrangement of catheters in the bladder, ureter, and diverticulum facilitates laparoscopic transperitoneal diverticulectomy of even a very large volume diverticulum.

Cystectomy↗
PubMed2004

Anatomic guide for port placement for daVinci robotic radical prostatectomy.

BACKGROUND AND PURPOSE: At present, robotic arm port placement for daVinci trade mark robot-assisted laparoscopic radical prostatectomy is based on the umbilicus. However, the robotic arm has a maximum manufactured required working distance of 25 cm. Accordingly, normal variability of patient height, weight, and umbilical location can leave the working arms too short to reach the membranous urethra. We present data to support port placement using the pubis, rather than the umbilicus, as the landmark. MATERIALS AND METHODS: If we assume the 25-cm working distance of the robot arm (Z) equals the hypotenuse of a triangle and the Y axis is the sum of the distance from the membranous urethra to the skin (Y1) plus the displacement of the skin secondary to CO(2) insufflation (Y2), then the horizontal distance X is from the robot port site to the pubis. To ascertain Y1, we randomly selected the CT scans of 25 men and measured the depth from the skin over the pubis to the membranous urethra. To determine Y2, we measured the change in height from the table of the port site after CO(2) insufflation in 11 robotic laparoscopic prostatectomies. RESULTS: The average distance of Y1 was 11 cm; Y2 was 6 cm. Using the formula (Z(2) - (Y1 + Y2)(2))(1/2), the maximum distance X from the port site to the pubis, for an average man, should not exceed 18 cm. CONCLUSION: The optimal landmark for calculating the placement of ports for the daVinci robotic arm placement should be the pubis and not the umbilicus. Tall men (>72 inches) are at risk for exceeding functional robot arm length, and in these men, port sites should not be more than 18 cm from the pubis.

Equipment Design↗
PubMed2004

Percutaneous approaches to renal cryoablation.

Minimally invasive approaches to small renal tumors continue to evolve. Cryotherapy is an attractive modality in that it can be delivered in a number of different ways, including laparoscopically and percutaneously. This article addresses the current state of percutaneous approaches to renal masses.

Cryosurgery↗
PubMed2004

Sealing percutaneous nephrolithotomy tracts with gelatin matrix hemostatic sealant: initial clinical use.

PURPOSE: Tubeless percutaneous nephrolithotomy (PCNL) has been performed at several centers with good success. However, these cases have been carefully selected with regard to short duration and smaller stone burden to prevent complications associated with the loss of access to the collecting system. We describe the use of gelatin matrix hemostatic sealant (FloSeal Baxter Medical, Fremont, California) as an adjunct to tubeless percutaneous nephrolithotomy to help preclude bleeding complications. MATERIALS AND METHODS: Two patients were treated with PCNL through a single nephrostomy tract. At the satisfactory conclusion of the cases the tract was occluded retrograde with an occlusion balloon catheter and gelatin matrix hemostatic sealant was injected down the nephrostomy tract. An indwelling stent and bladder catheter were placed following which all guidewires were removed and skin sutures were placed. RESULTS: The operative times were 75 and 180 minutes, respectively. Both patients had stable postoperative hemoglobin and no evidence of bleeding or obstruction on postoperative computerized tomography. CONCLUSIONS: Injection of gelatin matrix hemostatic sealant into the nephrostomy tract may be of value in preventing bleeding after PCNL. In this pilot experience it provided immediate and effective hemostasis.

Female↗
PubMed2004

Prospective comparison of the immunological and stress response following laparoscopic and open surgery for localized renal cell carcinoma.

PURPOSE: We prospectively compared the systemic immune and stress response of patients who underwent laparoscopic total nephrectomy (LRN) (14) and open nephrectomy (ON) (10) for renal cell carcinoma. The ON group comprised open radical (4), open total (2) and open partial (4) nephrectomy cases. MATERIALS AND METHODS: Only patients with no history of cancer or autoimmune disease and American Society of Anesthesiologists score 2 or less who were not using immunosuppressive drugs were selected. Peripheral venous blood was collected preoperatively and intraoperatively, and 24 hours, 2 weeks, 4 weeks and 3 months postoperatively. Blood was analyzed for stress markers (adrenalin, noradrenalin and cortisol), inflammatory response markers (C-reactive protein, white blood count and leukocyte count), lymphocytic response markers (CD3, CD4 and CD8), cytokines interleukin-2 and 4, interferon-alpha and tumor necrosis factor-alpha), HLA-DR expression and the proliferative response to mitogen stimulation using concanavalin A, phytohemagglutinin 10, and pokeweed mitogen. RESULTS: Mean tumor size +/- SD for ON and LRN was 5.6 +/- 2.4 and 4.5 +/- 1.6 cm, respectively (p = 0.21). The trends with time for all measured postoperative parameters were similar in the 2 groups. Inflammatory and stress response markers were statistically similar for in the groups at all time points. A significant difference between the groups was noted for the percentage of CD4+ and CD8+ lymphocytes. However, this difference was present preoperatively and there was no significant absolute change in these 2 parameters. The cytokine response and HLA-DR expression were similar in the 2 groups at all time points. Likewise, the lymphocytic stimulation index for concanavalin A, phytohemagglutinin and pokeweed mitogen were statistically similar for LRN and ON at all time points. CONCLUSIONS: The immunological and stress response after LRN and ON for renal cell carcinoma is similar. The few differences observed in measured parameters likely reflect preoperative differences in baseline and/or the contributory effect of anesthesia.

Carcinoma, Renal Cell↗
PubMed2004

Laparoscopic mid sagittal hemicystectomy and bladder reconstruction with small intestinal submucosa and reimplantation of ureter into small intestinal submucosa: 1-year followup.

PURPOSE: We evaluated the long-term results of laparoscopic hemicystectomy and bladder replacement with small intestinal submucosa (SIS) with ureteral reimplantation into the SIS material. MATERIALS AND METHODS: A total of 12 minipigs underwent laparoscopic hemicystectomy. Six pigs underwent bladder reconstruction with SIS and ipsilateral ureteral reimplantation. The remaining 6 control pigs underwent hemicystectomy and primary bladder closure with ipsilateral nephroureterectomy. Preoperative and followup evaluations included blood chemistry, radiography and urodynamic evaluations. The 6, 3, 6 and 9-week, and 12-month followup evaluations included biopsies. At 1 year the animals were sacrificed. Histopathological and contractility studies, and reverse transcriptase-polymerase chain reaction for growth factors and basement membrane components were performed. RESULTS: Bladder capacity and bladder compliance were similar in the 2 groups at all time points. One pig per group died, that is a control at the 9-month evaluation due to an anesthetic complication and an SIS pig 7 months after bladder reconstruction due to spontaneous bladder rupture at the anastomotic site. In the SIS group 4 of 5 surviving pigs had unobstructed reimplanted ureters without evidence of hydroureteronephrosis, while 1 had high grade obstruction at the reimplantation site. Histopathology study after 1 year revealed muscle at the graft periphery and center but it consisted of small fused bundles with significant fibrosis. Nerves were present at the graft periphery and center but they were decreased in number. CONCLUSIONS: Laparoscopic SIS bladder reconstruction and ureteral reimplantation into the SIS after hemicystectomy are technically feasible. However, compared to primary bladder closure no advantage in bladder capacity or compliance was documented.

Animals↗