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T S Corwin

Publications and source records attributed to T S Corwin.

7 recordsLinked to original sources
PubMed2001

Hemostatic laparoscopic partial nephrectomy: cable-tie compression.

OBJECTIVES: Laparoscopic partial nephrectomy (LPN) has generally been reserved for small exophytic lesions because of the limited hemostatic capabilities when excising large segments of renal parenchyma. To overcome this problem, we investigated a technique of laparoscopic reversible, regional hypoperfusion using a cable-tie to minimize blood loss and optimize exposure. METHODS: Ten domestic pigs underwent LPN after securing a cable-tie around one pole of the kidney and tightening it until the distal parenchymal surface blanched completely. Eight large amputations involving the collecting system and eight smaller amputations excluding the collecting system were performed using laparoscopic scissors. Fibrin glue was applied to seal the cut surface prior to cable-tie removal. Four pigs (4 large and 4 small amputations) were killed immediately and methylene blue was injected retrograde into the ureter to identify collecting system leaks. The remaining 6 pigs (4 large and 4 small amputations) were killed 4 weeks later and retrograde urograms were performed to assess collecting system integrity. RESULTS: Median cable-tie ischemia time was 15 minutes (range 7 to 48) and median blood loss was 30 mL (range 10 to 300). In each case, hemostasis was attained with fibrin glue. In the survival group, all 4 small amputations healed with a fibrotic scar. In the large amputation group, 1 animal died from urinary extravasation on postoperative day 4. The collecting systems of the remaining 3 pigs sealed completely. CONCLUSIONS: In the porcine model, cable-tie-assisted LPN provides an almost bloodless surgical field that facilitates rapid resection of large renal segments and hemostasis during a short ischemic period. We anticipate that this technique will broaden the clinical application of LPN.

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PubMed2001

Renal parenchymal injury after standard and mini percutaneous nephrostolithotomy.

PURPOSE: Mini percutaneous nephrostolithotomy was developed for use in children and in adults with a reduced renal reserve to minimize the morbidity and renal parenchymal damage presumed to occur with traditional percutaneous nephrostolithotomy. We compared the extent of renal injury incurred by different sized nephrostomy tracts in female farm pigs undergoing 11 or 30Fr percutaneous nephrostomy. MATERIALS AND METHODS: Bilateral percutaneous nephrostomy was attempted via a mid or lower pole calix under fluoroscopic guidance in 6 pigs. In 2 pigs the procedure was unsuccessful on 1 side, leaving 5 successfully established nephrostomy tracts on each side. In each pig the right percutaneous tract was dilated with a 28Fr dilating balloon and a 30Fr Amplatz working sheath (Cook Urological, Spencer, Indiana) was positioned in the collecting system. On the left side an 11Fr sheath (Cook Urological) was placed. The sheaths were removed after 1 hour and nephrostomy tubes (22Fr on the right and 8Fr on the left side) were left in place overnight and then removed. Six weeks later the pigs were sacrificed and the kidneys were harvested. The nephrostomy tracts were identified grossly and examined microscopically, and the fibrotic scar was measured using digital analysis. The volume of scar was estimated using the calculated volume of a cylinder. RESULTS: At kidney harvest all 10 kidneys appeared grossly normal. No intra-abdominal urine collection or perirenal hematoma was noted. Mean estimated scar volume of the 30 and 11Fr tracts was 0.29 and 0.40 cc, which translates into a mean fractional loss of parenchyma of 0.63% and 0.91%, respectively (p not significant). CONCLUSIONS: Renal parenchymal damage resulting from the creation of a nephrostomy tract is small compared to overall renal volume regardless of the size of the nephrostomy tract. Consequently there is no advantage to the use of a small access sheath based on renal scarring alone.

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PubMed2001

Laparoscopic radiofrequency thermal ablation of renal tissue with and without hilar occlusion.

PURPOSE: Few studies have evaluated the effect of radiofrequency thermal ablation on renal tissue, although it has been used clinically to treat small renal masses. We studied the size and histology of lesions created with radiofrequency thermal ablation administered via the laparoscopic approach with and without hilar occlusion in a porcine model. MATERIALS AND METHODS: The lower pole of each kidney was exposed laparoscopically in 11 farm pigs. In each kidney a 7-electrode dry radiofrequency thermal ablation probe was inserted at an identical location and deployed to a diameter of 2 cm. Energy was applied for 8 minutes at an average temperature of 100C. The left renal hilum of each pig was clamped during radiofrequency thermal ablation. Two pigs were sacrificed immediately, and 3 each were sacrificed at 24 hours, 2 and 4 weeks. The size and shape of the lesions created were measured and examined histologically. RESULTS: There were no intraoperative or postoperative complications. Laparoscopic ultrasound confirmed probe placement but did not monitor lesion progression. Acutely lesions were firm and white with a small adjacent hemorrhagic zone. Histological evaluation revealed preserved renal architecture but the loss of distinct cytoplasmic features. Nicotinamide adenine dinucleotide staining demonstrated no viable cells within the lesions. In surviving animals pelvicaliceal integrity was preserved. In the 2 and 4-week survival groups kidneys treated with hilar occlusion had larger lesions than nonoccluded kidneys but the differences were not significant at 4 weeks (3.2 x 2.7 x 2.5 cm. and 3.5 x 1.7 x 2.0, respectively, p >0.05). Histologically untreated parenchyma of hilar occluded kidneys demonstrated changes consistent with chronic pyelonephritis. In 1 kidney radiofrequency thermal ablation with hilar occlusion resulted in complete lower pole loss at 4 weeks. CONCLUSIONS: In the porcine model renal radiofrequency thermal ablation creates rapid and completely devitalized lesions of consistent size and shape. Hilar occlusion may result in slightly larger lesions but risks damage to the whole renal unit.

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