Biomedical subjects

David A Lifshitz

Publications and source records attributed to David A Lifshitz.

5 recordsLinked to original sources

PubMed2002

Stone fragmentation during shock wave lithotripsy is improved by slowing the shock wave rate: studies with a new animal model.

PURPOSE: The current trend toward ungated shock wave lithotripsy means that more patients are being treated with shock waves delivered at a rapid rate (120 shock waves per minute or greater). However, no benefit of an increased shock wave rate has been shown and in vitro studies indicate that slowing the shock wave rate actually improves stone fragmentation. We tested the effect of the shock wave rate on stone comminution in a new animal model. MATERIALS AND METHODS: Gypsum model stones were inserted via upper pole percutaneous access into the lower pole calix of the kidneys of female pigs weighing approximately 100 pounds. Shock wave lithotripsy was performed (400 shock waves uninterrupted at 20 kV. and 30 or 120 shock waves per minute) 2 hours later using an unmodified HM3 lithotriptor (Dornier Medical Systems, Marietta, Georgia). After en bloc excision of the urinary tract stone fragments were collected and sieved through 2 mm. mesh. The particles were weighed and surface area was determined. RESULTS: Stones treated at 30 shock waves per minute broke more completely than stones treated at 120 shock waves per minute. The percent of fragments greater than 2 mm. was significantly higher for stones treated at the fast rate of 120 versus the slow rate of 30 shock waves per minute (mean +/- SEM 81% +/- 14% versus 45% +/- 12%, p <0.005). When stone fragmentation was expressed as the percent increase in fragment surface area, significantly greater fragmentation occurred at the slower than at the more rapid rate (327% +/- 63% versus 135% +/- 136%, p <0.02). CONCLUSIONS: Slowing the rate of shock wave administration during shock wave lithotripsy significantly improves the efficiency of stone fragmentation in vivo.

Animals↗

PubMed2002

Multilayered small intestinal submucosa is inferior to autologous bowel for laparoscopic bladder augmentation.

PURPOSE: Bladder augmentation is most commonly performed with ileum. However, porcine small intestinal submucosa has been reported as a substitute for bowel for incorporation into the urinary tract. We assessed the feasibility and long-term 12-month results of laparoscopic bladder augmentation with ileum or multilayered small intestinal submucosa (Cook Biotech, Spencer, Indiana) in a porcine model. MATERIALS AND METHODS: We performed laparoscopically assisted hemicystectomy and bladder augmentation in 24 female Yucatan mini-pigs using an ileal segment (12) or multilayered small intestinal submucosa (12). The followup protocol included anesthetic bladder capacity, renal ultrasonography and serum chemistry. At 3, 6 and 12 months, respectively, 4 animals per group were scheduled for sacrifice and pathological analysis. RESULTS: Despite longer anastomotic time in the multilayered small intestinal submucosa group (120 versus 91 minutes, p = 0.026) total operative time was similar in the 2 groups. In each group bladder capacity increased with time but by 12 months bladder capacity was significantly better in the bowel than in the small intestinal submucosa group (825 versus 431 cc, p = 0.016). At 3 months pathological evaluation revealed that the multilayered regenerated bladder patch had shrunken and by 6 months it was replaced by dense calcified scar tissue. Long-term 6 and 12-month bladder capacity in the small intestinal submucosa group was the result of the regeneration of native bladder with exclusion of the whole multilayered patch in the majority of cases. CONCLUSIONS: Laparoscopic bladder augmentation using multilayered small intestinal submucosa produced functional and pathological results inferior to those of bowel at 12-month followup in a porcine model.

Animals↗

PubMed2002

Ureteroscopy as a first-line intervention for ureteral calculi in pregnancy.

BACKGROUND AND PURPOSE: Renal colic in pregnancy presents a diagnostic and therapeutic challenge. When conservative therapy fails or is not indicated, temporary measures such as ureteral stenting are often chosen as a first-line intervention, postponing definitive management until after delivery. We propose that advances in endoscopic equipment and anesthesia techniques dictate a more definitive strategy. PATIENTS AND METHODS: A retrospective analysis was performed on 10 consecutive pregnant patients presenting with renal colic necessitating intervention between April 1998 and April 2000. The mean patient age was 23 (range 17-31) years. One patient presented during the first trimester, six in the second, and three in the third. Four of the patients had a history of stone disease. All patients had flank pain at presentation, six on the left side and four on the right. Hematuria, fever, and nausea were present in eight, one and two patients, respectively. RESULTS: Ultrasound scanning was performed in all patients and showed a low sensitivity (28.5%) when compared with intraoperative findings. Ureteroscopy (rigid and/or flexible) was performed as a first-line intervention in six patients, in two of whom no stone was found. Percutaneous nephrolithotomy was carried out in one patient presenting with a nephrostomy tube. Double-J stents were placed in only three patients with specific indications, namely urinary infection, late gestational phase, and difficult ureteroscopy secondary to a narrow ureter. No obstetric or urologic complications were noted. The mean size of the stones retrieved in seven patients was 7 mm. CONCLUSIONS: Ureteroscopy may be considered a safe and effective first-line definitive therapeutic option in pregnant patients requiring intervention for stone disease.

Adolescent↗

PubMed2002

Transperitoneal laparoscopic renal surgery using blunt 12-mm trocar without fascial closure.

BACKGROUND AND PURPOSE: Conical blunt trocar insertion may eliminate the need for fascial closure (FC) in transperitoneal laparoscopic renal surgery. This concept applies to 12-mm blunt trocar placement through muscular parts of the abdominal wall, relying on muscle splitting and eventual muscle retraction when the trocar is removed. We retrospectively assessed the safety of fascial nonclosure (FNC) after 12-mm blunt port insertion. PATIENTS AND METHODS: Ninety transperitoneal laparoscopic renal procedures were performed between August 1999 and May 2000. Four ports (two 12 mm and two 5 mm) were usually used except for 30 donor nephrectomies, where an additional 5-mm port was used. The 12-mm trocars were inserted at the lateral border of the rectus muscle 5 cm below the costal margin and in the anterior axillary line 8 cm below the costal margin. Fascial closure was performed in 62 patients and nonclosure in 28 patients. Exclusion criteria for FNC included midline location, malnutrition, renal failure, and chronic use of steroids. Postoperative outcomes were compared in 20 patients with FNC matched with 20 patients with FC. RESULTS: At an average of 4.8 months of follow-up, none of the patients developed a trocar site hernia. No significant statistical differences were observed between the groups with regard to intraoperative and postoperative data. CONCLUSIONS: These two approaches appear to be equivalent in terms of patient morbidity and postoperative hospital stay. Fascial nonclosure after transperitoneal 12-mm blunt trocar insertion, through muscular parts of the abdominal wall may be safe and efficacious and eliminates the last step in transperitoneal laparoscopic renal surgery.

Adult↗

PubMed2002

Endoloop-assisted laparoscopic partial nephrectomy.

PURPOSE: To determine the safety and feasibility of Endoloop-assisted laparoscopic partial nephrectomy in a large-animal model. MATERIALS AND METHODS: Twelve female Yucatan mini-pigs underwent either left (N = 6) or right (N = 6) transperitoneal laparoscopic lower-pole nephrectomy following cinching of a 1-0 Vicryl suture loop (Endoloop) proximal to the resected lower pole until ischemic discoloration was achieved. The ischemic lower pole was excised with Endo-scissors and the lower pole removed using a laparoscopic bag. Follow-up involved evaluation under anesthesia with retrograde pyelography and intravenous urography and subsequent sacrifice for pathologic evaluation at 3 (N = 4), 14 (N = 4), or 60 (N = 4) days. RESULTS: All procedures were completed successfully. In two cases, the Endoloop slipped off the retained parenchyma. Both problems were corrected immediately with no sequelae. At sacrifice, all upper-pole renal segments functioned, as shown by urography, and no urinomas or abscesses were found. In one animal, there was moderate hydronephrosis presumably secondary to ureteral scarring, and in another, mild extravasation was demonstrated on the retrograde pyelogram. CONCLUSION: We were able to perform laparoscopic partial nephrectomy with the Endoloop safely and effectively in the current model. Modification of the Endoloop to allow more controlled pressure application may allow clinical application of this method for polar laparoscopic partial nephrectomy.

Animals↗