Biomedical subjects

Costas D Lallas

Publications and source records attributed to Costas D Lallas.

12 recordsLinked to original sources

PubMed2006

Hand port use for extraction during laparoscopic donor nephrectomy.

OBJECTIVES: To report our technique of laparoscopic donor nephrectomy using the hand port for specimen extraction. In 1999, our institution began a kidney transplant program. Donor nephrectomies have since been exclusively performed laparoscopically. Early in our experience, we used a specimen extraction bag to assist in graft removal, but encountered some complications. We subsequently changed our technique to include a hand port for specimen extraction. METHODS: A database of our experience was kept prospectively. The records of both donors and recipients were reviewed. We describe our technique of laparoscopic donor nephrectomy, including our new method of specimen extraction using a hand port. RESULTS: A total of 230 consecutive procedures were reviewed. We had excellent donor outcomes, including a mean operative time of 107.9 minutes and an estimated blood loss of 112.4 mL. In addition, the complication (12.6%) and open conversion (1.3%) rates were low. The time needed for specimen extraction decreased from 3.16 minutes to 1.16 minutes (P <0.05) after implementation of the hand port. CONCLUSIONS: The hand port modification decreased the extraction time and allowed for a safer method of extraction. We believe that the hand port facilitates a procedure that contains a small margin of error.

Adult↗

PubMed2006

Xanthine urolithiasis.

Xanthine calculi are uncommonly encountered stones. When they occur, they typically do so in association with inborn metabolic disorders such as hereditary xanthinuria or Lesch-Nyhan syndrome. They may also occur in association with states of profound hyperuricemia such as myeloproliferative disease after treatment with allopurinol. If the underlying disorder is not addressed, a high risk of stone recurrence exists. Therefore, to raise clinical awareness, we reviewed and report our experience in the treatment of patients with these stones, discussing the underlying pathophysiology and approach to treatment.

Adolescent↗

PubMed2004

Management of nephropleural fistula after supracostal percutaneous nephrolithotomy.

OBJECTIVES: Access to complex urinary tract pathology may require supracostal access placing patients at risk for intrathoracic complications. Our objective was to retrospectively review our experience with percutaneous renal surgery with a particular emphasis on identifying the incidence of nephropleural fistula and management of this unusual complication. METHODS: The records of 375 consecutive patients who underwent percutaneous renal surgery between 1993 and 2001 were reviewed. Supracostal access was placed to address the intrarenal pathologic findings most directly in 120 (26.0%) of the 462 tracts, with 87 (18.8%) above the 12th rib, 32 (6.9%) above the 11th rib, and 1 (0.2%) above the 10th rib. RESULTS: Of 375 patients, 4 (1%) developed a nephropleural fistula. Of the 87 with supracostal-12th rib access, 2 (2.3%) developed a nephropleural fistula, and 2 (6.3%) of the 32 with supracostal-11th rib access developed the same complication. The overall incidence of nephropleural fistulas in our patient population per access tract placed was 0.87% (4 of 462 percutaneous tracts), which increased to 3.3% (4 of 120) when considering only supracostal access. All patients were treated conservatively, although 1 patient required thoracoscopy with decortication for persistent pleural effusion. No further sequelae developed in any of the other 3 patients, and all fistulas had resolved at 3 months of follow-up. CONCLUSIONS: As aggressive percutaneous renal surgery with supracostal access to the collecting system becomes more common, the incidence of intrathoracic complications, including nephropleural fistula, may increase. Early recognition and management of a pleural injury is critical to avoid life-threatening situations. Low-morbidity measures are typically successful; however, more aggressive treatment may be required on occasion.

Adult↗

PubMed2004

Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation.

BACKGROUND AND PURPOSE: New-generation flexible ureteroscopes allow the management of proximal ureteral and intrarenal pathology with high success rates, including complete removal of ureteral and renal calculi. One problem is that the irrigation pressures generated within the collecting system can be significantly elevated, as evidenced by pyelovenous and pyelolymphatic backflow seen during retrograde pyelography. We sought to determine if the ureteral access sheath (UAS) can offer protection from high intrarenal pressures attained during routine ureteroscopic stone surgery. PATIENTS AND METHODS: Five patients (average age 72.6 years) evaluated in the emergency department for obstructing calculi underwent percutaneous nephrostomy (PCN) tube placement to decompress their collecting systems. The indications for PCN tube placement were obstructive renal failure (N=1), urosepsis (N=2), and obstruction with uncontrolled pain and elevated white blood cell counts (N=2). Flexible ureteroscopy was subsequently performed with and without the aid of the UAS while pressures were measured via the nephrostomy tube connected to a pressure transducer. Pressures were recorded at baseline and in the distal, mid, and proximal ureter and renal pelvis, first without the UAS, and then with the UAS in place. RESULTS: The average baseline pressure within the collecting system was 13.6 mm Hg. The mean intrarenal pressure with the ureteroscope in the distal ureter without the UAS was 60 mm Hg and with the UAS was 15 mm Hg. With the ureteroscope in the midureter, the pressures were 65.6 and 17.5 mm Hg, respectively; with the ureteroscope in the proximal ureter 79.2 and 24 mm Hg, and with the ureteroscope in the renal pelvis 94.4 and 40.6 mm Hg, respectively. All differences at each location were statistically significant (P<0.008). Compared with baseline, all pressures measured without the UAS were significantly greater, but only pressures recorded in the proximal ureter and renal pelvis after UAS insertion were significantly higher (P<0.03). CONCLUSIONS: The irrigation pressures transmitted to the renal pelvis and subsequently to the parenchyma are significantly greater during routine URS without the use of the UAS. The access sheath is potentially protective against pyelovenous and pyelolymphatic backflow, with clinical implications for the ureteroscopic management of upper-tract transitional cell carcinoma, struvite stones, or calculi associated with urinary tract infection.

Aged↗

PubMed2004

Internet based multi-institutional clinical research: a convenient and secure option.

PURPOSE: As randomized, prospective trials have become an integral part of clinical research, multi-institutional, collaborative research has become a necessity. However, it may be cumbersome for participants at remote facilities to participate because the submission and compilation of data and results are at times lengthy processes. Internet based clinical studies have been found to be a rapid, easily accessible, safe and secure method of performing multi-institutional trials. MATERIALS AND METHODS: The Internet was used at geographically distant medical centers to enroll patients into a multi-institutional, prospective, randomized trial for the management of lower pole renal calculi. The Clinical Research Web-based Information Center secure computer web based program (Simplified Clinical Data Systems, Amherst, New Hampshire) was established to input preliminary demographic and clinical data, randomize patients, and collect treatment and followup information without paper chart documentation. The primary investigators in the study were sent a questionnaire to determine the ease of use of this Internet based program. The results were tabulated. RESULTS: A total of 112 patients from 21 participating institutions were randomized into the secure web site for inclusion into a lower pole renal stone clinical trial. Of the investigators 64% responded to the questionnaire. The majority of those having enrolled patients into the study reported no difficulties or only minimal difficulties in navigating the web site. Moreover, investigators from remote locations throughout North America described the improved convenience, rapid transmission of information, and ability to review and update patient data as benefits of enrolling patients using the Internet. The Internet based system also permits the prompt compilation of data at the host research site for performing interim data assessments and eventually the final analysis. CONCLUSIONS: A web based data collection center allows for large, multi-institutional trials to be done with unprecedented accuracy and efficiency. Through centralization of data capture, and real-time study monitoring and data analysis the system removes these responsibilities from those at individual test sites, permitting investigators to concentrate instead on other aspects of the study and its progress. State-of-the-art security protects all information to ensure confidentiality. The Internet may prove to be an invaluable tool in the future of clinical research.

Biomedical Research↗

PubMed2003

Assessment of stricture formation with the ureteral access sheath.

OBJECTIVES: To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma. METHODS: Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients. RESULTS: The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor. CONCLUSIONS: The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.

Adolescent↗

PubMed2003

Use of bipolar laparoscopic forceps to occlude and transect the retroperitoneal vasculature: a porcine model.

BACKGROUND AND PURPOSE: Surgical clips are commonly employed during laparoscopic radical nephrectomy to ligate perihilar vessels reliably, yet these clips can interfere with the application of a vascular stapler to major vessels, potentially leading to catastrophic hemorrhage. We assessed the efficacy of the PlasmaKinetic trade mark (PK) bipolar cutting forceps (Gyrus Medical, Minneapolis, MN) as a single modality in coagulating and dividing the retroperitoneal vessels in a swine model. MATERIALS AND METHODS: Three 40- to 50-kg domestic swine (six renal units) underwent celiotomy and retroperitoneal exposure. The inferior vena cava (IVC) and the renal, gonadal, and iliac vessels were isolated, and, using 5- and 10-mm forceps, coagulated and divided. The mean diameter of the renal vein was 8.7 mm, the renal artery 6.5 mm, and the IVC 14 mm. RESULTS: Hemostasis was achieved consistently using the 5-mm and 10-mm PK Cutting Forceps on the renal artery, renal vein, and gonadal vein. The 10-mm forceps coagulated the iliac veins and IVC 83% of the time with only a single application. Larger vessels or vessels with higher inherent vascular pressure required additional applications of the device to achieve hemostasis. All animals were hemodynamically stable through division of the IVC, as measured by heart rate and pulse oximetry. No complications were noted with the device or using the cutting element. CONCLUSIONS: The PK bipolar cutting forceps appear to be effective in controlling and dividing the renal hilar vessels and larger low-pressure vessels of the porcine retroperitoneum, with no gross damage to adjacent structures. Although further studies are necessary before use during laparoscopic nephrectomy in humans, these results are promising. Bipolar cutting forceps may prove to be a safe, cost-effective, and time-saving device with numerous applications during urologic laparoscopy.

Animals↗

PubMed2003

Pain after percutaneous nephrolithotomy: impact of nephrostomy tube size.

BACKGROUND AND PURPOSE: Percutaneous nephrolithotomy (PCNL) is the procedure of choice for managing large renal calculi. Investigations have recently focused on reducing the morbidity of the procedure and improving postoperative patient comfort by using smaller endoscopic instruments. We sought to evaluate the effect of a smaller percutaneous drainage catheter on postoperative pain. PATIENTS AND METHODS: Thirty consecutive patients were randomized to receive either a 10F pigtail catheter or a 22F Councill-tip catheter for their percutaneous drainage after PCNL. The demographics were similar in the two groups, as was the rate of supracostal access (47% v 43%, respectively). Self-assessed analog pain scores were collected at 6 hours postoperatively as well as on the morning of the first and second postoperative days (POD). Total narcotic usage was tabulated using morphine equivalents. Complications, including the change from baseline hematocrit, were reviewed. RESULTS: There was no significant difference in the change in hematocrit (6.8 v 6.2 percentage points, respectively). Those patients with the smaller nephrostomy tube noted significantly lower pain scores at 6 hours (3.75 v 5.3; P=0.03). Although the pain scores were lower on POD 1 and 2 for the 10F catheter group, the difference was not statistically different (1.9 v 2.9 and 1.25 v 1.9, respectively; both P>0.05). The patients having the 10F catheter required fewer narcotics: 78 mg v 91 mg, although the difference was not statistically significant. CONCLUSION: The use of a small drainage catheter after PCNL is associated with lower pain scores in the immediate postoperative period, yet no statistically significant benefit to the patient with regard to comfort is demonstrated beyond 6 hours. In addition, there is a trend toward reduced narcotic requirements. Finally, there is no apparent increase in patient morbidity from the use of the smaller nephrostomy tubes.

Catheterization↗

PubMed2002

In vitro comparison of standard ultrasound and pneumatic lithotrites with a new combination intracorporeal lithotripsy device.

OBJECTIVES: A new combination intracorporeal lithotripter (Lithoclast Ultra) has been developed that incorporates the beneficial effects of pneumatic lithotripsy (rapid stone fragmentation) and ultrasound lithotripsy (rapid fragment removal). An in vitro study was performed to assess the efficiency of stone fragmentation and clearance of this new combination intracorporeal lithotripter compared with currently available ultrasound and pneumatic units. METHODS: Pneumatic and ultrasound lithotrites, along with the combination pneumatic/ultrasound unit, were used through a rigid 27F nephroscope to fragment and remove phantom stones made of BegoForm. The mean fragment removal times and stone fragment sizes for the standard ultrasound and pneumatic devices were compared with the combination unit to determine the completeness and efficiency of stone fragmentation and removal. RESULTS: The average time for stone clearance using the pneumatic and ultrasound devices was 23.8 and 12.9 minutes, respectively. The combination pneumatic/ultrasound unit was significantly more efficient, requiring only 7.4 minutes to completely fragment and clear all stone material (P <0.002). In addition, the average size of the 15 largest fragments removed was significantly less with the combination device than with the pneumatic and ultrasound lithotrites (1.67 mm versus 9.07 mm and 3.67 mm, respectively, P <0.00001). CONCLUSIONS: The combination of pneumatic and ultrasound capabilities in a newly developed lithotrite exhibited a significantly enhanced ability to fragment and clear phantom stones compared with standard ultrasound or pneumatic devices alone. These preliminary studies suggest that this combination pneumatic/ultrasound lithotripter may be an ideal device for the expeditious removal of large-volume renal or bladder calculi. Additional studies are warranted to better assess the capabilities of this new device in treating human stones of various compositions and its safety, as well as the optimal power and frequency settings.

Equipment Design↗

PubMed2002

Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement.

BACKGROUND AND PURPOSE: The ureteral access sheath has positively impacted ureteroscopy by decreasing operative times and increasing success rates. However, as previous studies have suggested that large-caliber endoscopes may cause ureteral ischemia, concern has been raised about the impact of access sheath insertion on ureteral blood flow. We sought to determine whether the access sheath compromises ureteral blood supply and, if so, causes ischemic damage to the ureter during ureteroscopic procedures. MATERIALS AND METHODS: Using a swine animal model, ureteral blood flow was measured with a laser Doppler flowmeter. Eleven ureteral units were randomized into four study groups: those dilated with 10F-12F, 12F-14F, and 14F-16F access sheaths (N = 3 per group) and an undilated control group (N = 2). Blood flow measurements were obtained from the proximal ureter via laser Doppler flowmetry for 70 minutes at 5-minute intervals. Hemodynamic variability was controlled for through intraoperative heart rate and oxygen saturation monitoring, as well as a second Doppler probe that was placed on the animal's skin, from which readings were also taken every 5 minutes. Results were correlated with histopathologic findings. RESULTS: The control group demonstrated little ureteral blood flow variability over the course of 70 minutes. The study groups that were dilated with sheaths, however, all showed a decrease in ureteral blood flow after access sheath insertion, with the flow in animals dilated with 12F-14F and 14F-16F sheaths dropping below 50% of baseline. This initial drop in blood flow was followed by a gradual increase from nadir toward baseline values over the course of the study. On average, the 14F-16F group reached nadir more quickly and took longer to restore its ureteral blood flow. All animals remained hemodynamically stable throughout the study, showing only minimal variability in heart rate, oxygen saturation, and skin blood flow over the 70-minute experiment. Histologically, there was no evidence of ischemic damage in any of the study groups at 72 hours. CONCLUSIONS: In this animal model, the access sheath does cause a transient decrease in ureteral blood flow. Nonetheless, compensatory mechanisms of the ureteral wall restore blood flow to near-baseline rates and preserve urothelial integrity, suggesting that use of the ureteral access sheath remains a safe adjunct to flexible ureteroscopy. Because the chronic effects of the access sheath have yet to be elucidated, care must be taken in selecting an appropriate-size sheath for each individual case. Preventive measures may be available to help avoid sheath-related ureteral injury in those patients identified as high risk.

Animals↗

PubMed2002

Autologous dendritic cells transfected with prostate-specific antigen RNA stimulate CTL responses against metastatic prostate tumors.

Autologous dendritic cells (DCs) transfected with mRNA encoding prostate-specific antigen (PSA) are able to stimulate potent, T cell-mediated antitumor immune responses in vitro. A phase I trial was performed to evaluate this strategy for safety, feasibility, and efficacy to induce T cell responses against the self-protein PSA in patients with metastatic prostate cancer. In 13 study subjects, escalating doses of PSA mRNA-transfected DCs were administered with no evidence of dose-limiting toxicity or adverse effects, including autoimmunity. Induction of PSA-specific T cell responses was consistently detected in all patients, suggesting in vivo bioactivity of the vaccine. Vaccination was further associated with a significant decrease in the log slope PSA in six of seven subjects; three patients that could be analyzed exhibited a transient molecular clearance of circulating tumor cells. The demonstration of vaccine safety, successful in vivo induction of PSA-specific immunity, and impact on surrogate clinical endpoints provides a scientific rationale for further clinical investigation of RNA-transfected DCs in the treatment of human cancer.

Cancer Vaccines↗

PubMedDate not supplied

The development of a laparoscopic donor nephrectomy program in a de novo renal transplant program: Evolution of technique and results in over 200 cases.

BACKGROUND AND OBJECTIVES: In 1999, our institution began a kidney transplant program with collaboration between the departments of General Surgery/Transplantation and Urology. From the onset, donor nephrectomies were performed laparoscopically and are currently the domain of Urology, which had no prior laparoscopic experience before this undertaking. We reviewed our experience. METHODS: A database of our experience was kept prospectively from June 1999 to November 2004. Records of both donors and recipients were reviewed. Special attention was directed toward our changes in technique and their relationship to outcomes, with emphasis on graft extraction and overall complication rates. RESULTS: We reviewed the records of 205 consecutive procedures. We report excellent donor outcomes, including mean operative time (112 minutes), estimated blood loss (120 mL), and length of stay (2.3 days). Complication (14.1%) and open conversion (1.5%) rates were low. For the recipients, early (98.0%) and 1-year (94.7%) graft survival, and ureteral ischemia (2.4%) rates were also appropriate with contemporary experience. CONCLUSIONS: We report our results on laparoscopic donor nephrectomy in a de novo renal transplant program. Because of this experience, we have ventured into other horizons of urologic laparoscopy and currently produce enough volume to support a laparoscopic fellowship. We feel that a productive donor nephrectomy program can enhance urologic laparoscopic programs and should be taken advantage of when available.

Adult↗