1415Vol. 11 | No. 02 | March- April 2014 |U R O LO G Y J O U R N A L Department of Urology, Gradu- ate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, 2630 Sugitani, Toyama 930- 0194, Japan. Tetsuo Nozaki, Akihiro Morii, Yasuyoshi Fujiuchi, Hideki Fuse The Effect of Selective Renal Parenchy- mal Clamping during Laparoscopic Par- tial Nephrectomy on Early Postoperative Renal Function: A Preliminary Report Corresponding Author: Tetsuo Nozaki, MD Department of Urology, Gradu- ate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, 2630 Sugitani, Toyama 930- 0194, Japan. Tel: +81 76 434 2281 Fax: +81 76 434 5039 E-mail: nozaki0921@yahoo. co.jp Received April 2013 Accepted October 2013 Purpose:‎A‎major‎concern‎when‎performing‎laparoscopic‎partial‎nephrectomy‎(LPN)‎is‎poten- tial‎postoperative‎renal‎dysfunction.‎The‎objective‎of‎this‎study‎was‎to‎compare‎the‎effects‎of‎ LPN‎with‎selective‎renal‎parenchymal‎clamping‎(SRPC)‎(LPNSRPC)‎and‎LPN‎using‎micro- wave‎tissue‎coagulation‎(MTC)‎(LPNMTC)‎on‎postoperative‎renal‎function. Materials and Methods:‎This‎study‎included‎12‎patients‎(5‎men‎and‎7‎women)‎who‎under- went‎LPNSRPC‎(n‎=‎6)‎or‎LPNMTC‎(n‎=‎6)‎for‎exophytic‎tumors.‎Renal‎scanning‎with‎techne- tium-99m‎diethylenetriaminepentaacetic‎acid‎(Tc-99m‎DTPA)‎was‎performed‎preoperatively‎ and‎postoperatively‎at‎1‎month‎in‎all‎patients.‎‎ Results:‎The‎mean‎tumor‎size,‎surgical‎duration,‎and‎intraoperative‎blood‎loss‎were‎similar‎ in‎both‎groups.‎In‎the‎LPNMTC‎group,‎although‎not‎significant,‎the‎mean‎postoperative‎glo- merular‎filtration‎rate‎(GFR)‎values‎in‎the‎affected‎kidneys‎were‎decreased‎compared‎to‎the‎ preoperative‎values.‎When‎evaluating‎the‎affected‎renal‎function‎by‎split‎function‎(SF),‎the‎ mean‎postoperative‎SF‎in‎the‎affected‎kidneys‎was‎significantly‎decreased‎compared‎to‎the‎ preoperative‎value.‎In‎the‎LPNSRPC‎group,‎the‎mean‎postoperative‎GFR‎and‎SF‎in‎the‎affected‎ kidneys‎were‎not‎significantly‎changed‎compared‎with‎the‎preoperative‎values‎ Conclusion:‎ Our‎ preliminary‎ experience‎ demonstrates‎ that‎ LPNSRPC‎ facilitates‎ maximal‎ nephron-sparing‎surgery‎without‎collateral‎thermal‎damage‎causing‎renal‎impairment. Keywords:‎nephrectomy;‎methods;‎laparoscopy;‎blood‎loss;‎pilot‎projects;‎carcinoma;‎renal‎ cell;‎kidney‎neoplasms;‎surgery;‎treatment‎outcome. LAPAROSCOPIC UROLOGY 1416 | INTRODUCTION Partial‎nephrectomy‎(PN)‎is‎recognized‎as‎a‎stand-ard‎of‎care‎for‎localized‎small‎renal‎masses.(1)‎Re-cently,‎laparoscopic‎partial‎nephrectomy‎(LPN)‎has‎ been‎shown‎to‎have‎equivalent‎oncological‎outcomes‎and‎ improved‎morbidity‎compared‎to‎the‎open‎technique.(2) As a‎promising‎minimally‎invasive‎nephron-sparing‎surgery,‎ LPN‎is‎gaining‎popularity‎in‎the‎treatment‎of‎select‎renal‎ tumors.‎Furthermore,‎renal‎function‎appears‎to‎have‎a‎high‎ effect‎on‎non-cancer-related‎mortality,‎and‎another‎major‎ concern‎of‎LPN‎is‎maximum‎preservation‎of‎residual‎renal‎ function.(3)‎In‎particular,‎when‎applying‎LPN‎to‎a‎growing‎ number‎of‎patients‎in‎an‎aging‎cohort‎with‎a‎high‎preva- lence‎of‎preoperative‎latent‎or‎apparent‎chronic‎renal‎insuf- ficiency,‎postoperative‎renal‎function‎should‎be‎considered‎ in‎all‎treatment‎decisions.(4)‎However,‎to‎date,‎no‎LPN‎sat- isfies‎all‎the‎criteria‎for‎clinical‎practice.‎ Recently,‎Simon‎and‎colleagues‎reported‎a‎novel‎technique‎ of‎selective‎clamping‎to‎establish‎regional‎ischemia‎in‎LPN,‎ using‎the‎laparoscopic‎Simon‎clamp‎(Aesculap‎AG,‎Tuttlin- gen,‎Germany).(5)‎The‎laparoscopic‎Simon‎clamp‎is‎newly‎ developed‎and‎includes‎a‎standard‎locking‎ratchet‎handle‎and‎ an‎open‎jaw‎diameter‎of‎70‎mm.‎The‎clamp‎can‎be‎placed‎ along‎the‎renal‎parenchyma‎immediately‎surrounding‎the‎re- nal‎mass,‎thus‎creating‎regional‎ischemia‎and‎limiting‎injury‎ to‎the‎preserved‎portion‎of‎the‎kidney.‎LPN‎with‎selective‎ renal‎ parenchymal‎ clamping‎ (LPNSRPC)‎ using‎ the‎ lapa- roscopic‎Simon‎clamp‎may‎thus‎minimize‎potential‎injury‎ to‎the‎unaffected‎portion‎of‎the‎kidney.‎However,‎its‎effect‎ on‎renal‎function‎remains‎unknown.‎The‎main‎objective‎of‎ this‎study‎was‎to‎evaluate‎the‎effect‎of‎LPNSRPC‎on‎post- operative‎ renal‎ function‎ using‎ technetium-99m‎ diethylen- etriaminepentaacetic‎acid‎(Tc-99m‎DTPA)‎scanning.‎As‎the‎ majority‎of‎patients‎who‎undergo‎LPN‎have‎a‎functioning‎ contralateral‎kidney,‎assessment‎of‎postoperative‎creatinine‎ levels‎to‎determine‎the‎effect‎of‎LPN‎on‎renal‎function‎is‎ equivocal,‎ since‎ serum‎ creatinine‎ conveys‎ the‎ total‎ renal‎ function,‎which‎would‎be‎affected‎by‎the‎contralateral‎kid- ney.‎To‎evaluate‎the‎postoperative‎function‎of‎the‎affected‎ kidney‎separately‎from‎the‎non-affected‎kidney‎is‎important‎ to‎examine‎the‎specific‎utility‎of‎LPN.‎The‎Tc-99m‎DTPA‎ renography‎is‎a‎commonly‎accepted‎and‎simple‎method‎for‎ measurement‎of‎individual‎renal‎function.‎It‎provides‎nota- ble‎information‎such‎as‎quantitative‎individual‎renal‎function‎ and‎ pathophysiologic‎ changes‎ of‎ the‎ kidney.(6)‎ Moreover,‎ calculation‎of‎SF‎on‎the‎basis‎of‎renal‎scan‎shows‎the‎func- tions‎of‎each‎kidney‎separately‎and‎thus‎more‎accurately‎re- flects‎the‎influence‎of‎surgery‎on‎the‎affected‎kidney.(7)‎To‎the‎ best‎of‎our‎knowledge,‎this‎is‎the‎first‎report‎to‎evaluate‎the‎ effect‎of‎LPNSRPC‎on‎renal‎function.‎We‎also‎compared‎the‎ changes‎in‎renal‎function‎between‎LPNSRPC‎and‎LPN‎using‎ microwave‎tissue‎coagulation‎(MTC)‎(LPNMTC). MATERIALS AND METHODS Study Subjects From‎October‎2010,‎12‎consecutive‎patients‎(5‎men‎and‎7‎ women;‎mean‎age‎62.8‎±‎13.6‎years;‎range‎36-77‎years)‎were‎ enrolled‎in‎this‎study.‎Six‎patients‎who‎were‎undergoing‎LPN- SRPC‎were‎compared‎with‎6‎patients‎who‎were‎undergoing‎ LPNMTC.‎ All‎ patients‎ had‎ undergone‎ preoperative‎ spiral‎ computed‎tomography‎(CT)‎with‎3-dimensional‎reconstruc- tion‎or‎magnetic‎resonance‎imaging‎(MRI)‎to‎precisely‎delin- eate‎the‎renal‎mass.‎The‎complexity‎of‎the‎renal‎tumor‎was‎ classified‎using‎the‎R.E.N.A.L.‎nephrometry‎scoring‎system. (8)‎The‎presence‎of‎peripherally‎located,‎solitary,‎small‎renal‎ tumors‎was‎the‎operative‎indication‎for‎LPNSRPC.‎In‎LPN- MTC,‎in‎order‎to‎avoid‎unexpected‎thermal‎damage‎to‎the‎col- lecting‎system,‎operative‎indications‎were‎exophytic‎renal‎tu- mors‎with‎adequate‎intervening‎renal‎parenchyma‎as‎far‎as‎the‎ renal‎collecting‎system‎(<‎10‎mm).‎Table‎1‎shows‎the‎preop- erative‎patient‎characteristics‎and‎renal‎tumor‎data.‎LPNSRPC‎ patients‎were‎generally‎younger‎than‎LPNMTC‎patients,‎but‎ the‎difference‎was‎not‎statistically‎significant‎(P‎=‎.200).‎There‎ was‎no‎significant‎difference‎in‎tumor‎diameter‎and‎nephrom- etry‎score‎seen‎between‎the‎LPNSRPC‎and‎LPNMTC‎groups‎ (P‎=‎.878‎and‎.614,‎respectively).‎In‎the‎LPNSRPC‎group,‎ there‎was‎1‎case‎of‎the‎imperative‎case.‎ We‎prospectively‎evaluated‎the‎effects‎on‎renal‎function‎using‎ Tc-99m‎DTPA‎scanning‎preoperatively‎and‎postoperatively‎at‎ 1‎month‎in‎all‎patients.‎Split‎function‎(SF)‎was‎calculated‎from‎ renograms.‎All‎results‎are‎expressed‎as‎mean‎and‎SD.‎Statisti- cal‎significance‎was‎determined‎using‎the‎Wilcoxon‎signed- rank‎test‎between‎preoperative‎and‎postoperative‎renal‎values.‎ A P‎value‎of‎<‎.05‎was‎considered‎statistically‎significant.‎ LPNSRPC Surgical Technique After‎administration‎of‎general‎anesthesia,‎the‎patient‎was‎ placed‎in‎the‎lateral‎decubitus‎position.‎Both‎transperitoneal‎ and retroperitoneal approaches were used according to the Laparoscopic Urology 1417Vol. 11 | No. 02 | March- April 2014 |U R O LO G Y J O U R N A L surgeon’s‎discretion.‎At‎first,‎the‎kidney‎was‎dissected‎cir- cumferentially‎and‎fully‎mobilized.‎The‎renal‎pedicle‎was‎ not‎ routinely‎ dissected.‎After‎ incising‎ the‎ Gerota’s‎ fascia‎ to‎expose‎the‎renal‎mass,‎the‎laparoscopic‎ultrasonography‎ using‎a‎5-10‎MHz‎flexible‎laparoscopic‎transducer‎(Aloka,‎ Wallingford,‎CT,‎USA)‎ was‎performed‎ to‎ identify‎ the‎ tu- mor‎location‎and‎the‎surgical‎margins.‎Then,‎12-mm‎ports‎ were‎placed‎in‎the‎ideal‎site‎to‎clamp‎the‎renal‎parenchyma.‎ Using‎electrocautery‎scissors,‎the‎incision‎line‎was‎marked‎ circumferentially‎approximately‎1‎cm‎from‎the‎tumor‎mar- gins‎ on‎ the‎ renal‎capsule.‎The‎ laparoscopic‎Simon‎clamp‎ was‎introduced‎through‎the‎12-mm‎port‎to‎allow‎for‎closure,‎ and‎it‎was‎locked‎in‎place‎along‎the‎tumor‎margin‎in‎order‎ to‎create‎regional‎ischemia‎(Figure‎1).‎Because‎the‎kidney‎ was‎fully‎mobilized,‎once‎the‎Simon‎clamp‎was‎closed,‎it‎ allowed‎for‎rotation‎of‎the‎kidney,‎thus‎providing‎optimal‎ tumor‎visualization‎and‎facilitating‎tumor‎excision.‎The‎pre- served‎portion‎of‎the‎kidney‎was‎perfused‎normally;‎there- fore,‎the‎tumor‎could‎be‎removed‎without‎any‎hurry‎or‎fear‎ of‎renal‎ischemia.‎The‎Simon‎clamp‎provided‎a‎uniform‎and‎ constant‎pressure‎over‎the‎length‎of‎the‎jaws,‎permitting‎cold‎ excision‎to‎be‎performed‎in‎a‎nearly‎bloodless‎field‎(Figure‎ 2).‎After‎complete‎tumor‎excision,‎biopsy‎specimens‎from‎ the‎tumor‎bed‎were‎sent‎for‎frozen-section‎study.‎The‎jaw‎ pressure‎was‎then‎temporarily‎reduced‎to‎better‎visualize‎the‎ bleeding site, which was then cauterized by bipolar electro- cautery.‎If‎necessary,‎ongoing‎bleeding‎from‎the‎injured‎ves- sels‎was‎repaired‎using‎figure-of-8‎sutures‎with‎4-0‎Vicryl.‎ After‎achieving‎good‎hemostasis,‎the‎Simon‎clamp‎was‎re- moved.‎The‎presence‎of‎urine‎leakage‎was‎investigated‎by‎ injecting‎indigotindisulfonate‎sodium‎intravenously.‎If‎entry‎ into‎the‎collecting‎system‎was‎noted,‎intracorporeal‎freehand‎ suture‎repair‎of‎the‎pelvicalyceal‎system‎was‎performed.‎Pa- renchymal‎sutures‎using‎2-0‎Vicryl‎sutures‎on‎a‎small‎half- circle‎(SH)‎needle‎were‎placed‎for‎cross-compression‎along‎ the‎defect.‎Rolled‎Surgicel‎bolsters‎were‎then‎applied‎to‎the‎ tumor‎bed,‎and‎the‎pledgeted‎parenchymal‎sutures‎were‎tied‎ down‎across‎the‎bolsters‎to‎provide‎additional‎compressive‎ hemostasis.‎The‎tumor‎was‎placed‎in‎an‎endoscopic-bag‎de- vice‎and‎removed.‎A‎drain‎was‎subsequently‎placed,‎and‎the‎ port‎sites‎were‎closed‎in‎the‎routine‎fashion. LPNMTC Surgical Technique Both‎ transperitoneal‎ and‎ retroperitoneal‎ approaches‎ were‎ used‎according‎to‎the‎surgeon’s‎discretion.‎After‎obtaining‎ tumor‎exposure,‎through‎a‎5-mm‎port,‎a‎laparoscopic‎MTC‎ probe‎(Microtaze‎OT-110M,‎Aswell‎Co.,‎Osaka,‎Japan)‎was‎ introduced.‎The‎MTC‎bends‎at‎its‎distal‎near-object‎end‎and‎ causes‎thermal‎coagulation‎of‎tissues‎using‎microwave‎ener- gy‎(2,459‎MHz).‎This‎energy‎is‎transmitted‎from‎a‎generator‎ through‎a‎coaxial‎cable‎to‎a‎probe,‎which‎consists‎of‎a‎hand‎ piece‎and‎a‎needle-like‎electrode.‎The‎rapid‎oscillation‎of‎ water‎particles‎caused‎by‎microwaves‎results‎in‎a‎high‎tem- perature, inducing cone-shaped tissue coagulation around the needle‎that‎is‎7-10‎mm‎in‎width‎without‎any‎carbonization.‎In‎ LPN,‎MTC‎was‎applied‎peripherally‎to‎the‎healthy‎parenchy- ma‎surrounding‎ the‎ tumor‎with‎circumferential‎punctures,‎ producing‎coagulation‎of‎a‎conical-shaped‎portion‎of‎tissue.‎ Subsequently,‎ the‎base‎of‎ the‎ tumor‎was‎resected‎using‎a‎ Renal Parenchymal Clamping during Laparoscopic Partial Nephrectomy | Nozaki et al Figure 1. The laparoscopic Simon clamp was placed at a distance from the tumor edge. Figure 2. The resection of the tumor could easily be performed in a nearly bloodless operative field. 1418 | Laparoscopic Urology combination‎of‎conventional‎5-mm‎laparoscopic‎scissors‎and‎ blunt‎dissection‎with‎a‎laparoscopic‎aspirator‎without‎clamp- ing‎the‎renal‎pedicle.‎After‎complete‎tumor‎excision,‎biop- sies‎from‎the‎tumor‎bed‎were‎sent‎for‎frozen-section‎study.‎ The‎presence‎of‎urine‎leakage‎was‎investigated‎by‎injecting‎ indigotindisulfonate‎ sodium‎ intravenously.‎ After‎ confirm- ing‎ complete‎ hemostasis‎ and‎ clear‎ margins,‎ the‎ specimen‎ was‎placed‎in‎the‎laparoscopic‎bag‎and‎retrieved‎through‎the‎ abdominal‎incision.‎In‎LPNMTC,‎the‎application‎of‎bolster,‎ sealant,‎or‎parenchymal‎stitches‎was‎not‎necessary.‎ RESULTS Table‎2‎shows‎surgical‎outcomes‎for‎patients‎who‎underwent‎ LPNSRPC‎and‎LPNMTC.‎Both‎LPNSRPC‎and‎LPNMTC‎ were‎successful‎in‎all‎patients,‎and‎conversion‎to‎open‎sur- gery‎or‎ischemic‎LPN‎was‎not‎required.‎There‎were‎no‎sig- nificant‎differences‎in‎the‎mean‎operative‎time,‎mean‎blood‎ loss‎and‎mean‎Hb‎decrease.‎In‎the‎LPNSRPC‎group,‎the‎mean‎ selective‎clamping‎time‎was‎48.8‎±‎11.3‎min‎(44-59‎min).‎All‎ patients‎had‎negative‎surgical‎margins.‎Postoperative‎com- plications‎such‎as‎delayed‎hemorrhage,‎arteriovenous‎fistula,‎ and‎urinary‎leaks‎did‎not‎develop‎in‎any‎of‎the‎patients.‎ Table‎3‎shows‎the‎perioperative‎renal‎function‎data.‎In‎both‎ groups,‎the‎mean‎postoperative‎creatinine‎did‎not‎significant- ly‎differ‎from‎the‎preoperative‎values.‎None‎of‎the‎patients‎ developed‎acute‎renal‎failure‎during‎the‎postoperative‎period.‎ In‎both‎groups,‎the‎mean‎postoperative‎glomerular‎filtration‎ rate‎(GFR)‎of‎both‎kidneys‎calculated‎from‎the‎renal‎scan‎ was‎not‎significantly‎changed‎compared‎to‎the‎preoperative‎ values.‎ In‎the‎LPNSRPC‎group,‎the‎mean‎postoperative‎GFR‎values‎ in‎the‎affected‎kidneys‎did‎not‎significantly‎differ‎from‎the‎ preoperative‎values‎(41.4‎±‎18.5‎mL/min‎vs.‎38.7‎±‎17.7‎mL/ min,‎P‎=‎.562).‎When‎evaluating‎each‎kidney‎separately‎us- ing‎the‎renal‎scan,‎SF‎more‎accurately‎reflected‎the‎effect‎ of‎surgery‎on‎the‎affected‎kidney.(7)‎The‎mean‎postoperative‎ SF‎ in‎ the‎ affected‎ kidney‎ was‎ not‎ significantly‎ decreased‎ compared‎to‎the‎preoperative‎value‎(48.8‎±‎9.8%‎vs.‎51.9‎±‎ 5.3%,‎P‎=‎.312).‎In‎addition,‎mean‎postoperative‎SF‎in‎the‎ non-affected‎kidney‎was‎not‎significantly‎changed‎compared‎ with‎the‎preoperative‎value‎(48.0‎±‎5.3%‎vs.‎51.2‎±‎9.8%,‎ P‎=‎.311).‎In‎the‎LPNMTC‎group,‎although‎not‎significant,‎ the‎mean‎postoperative‎GFR‎values‎in‎the‎affected‎kidneys‎ calculated‎from‎the‎renal‎scans‎were‎reduced‎as‎compared‎to‎ the‎preoperative‎values‎(29.6‎±‎8.8‎mL/min‎vs.‎36.8‎±‎10.8‎ mL/min,‎P‎=‎.093).‎In‎the‎affected‎kidneys,‎mean‎postopera- Table 1. preoperative patient characteristics and renal tumor data. Age Sex Side Tumor Size (mm) Nephrometry Score Approach Pathology LPNMTC 1 79 M Lt 20 4 T CCC 2 81 M Lt 25 6 R CCC 3 59 M Rt 18 7 T CCC 4 49 M Rt 25 5 T Chromophobe RCC 5 68 M Rt 23 6 R CCC Mean ± SD 68.0 ± 12.2 21.8 ± 0.2 5.83±1.16 LPNSRPC 6 49 F Lt 25 6 R Hemorrhagic renal cyst 7 36 F Lt 20 7 T CCC 8 62 M Lt 23 5 T CCC 9 77 F Lt 26 4 T CCC 10 62 F Lt 21 6 T Papillary RCC 11 60 F Lt 14 5 T CCC Mean ± SD 57.7 ± 13.9 21.5 ± 4.3 5.60 ± 1.14 Keys: LPNMTC, laparoscopic partial nephrectomy using microwave tissue coagulation; LPNSRPC, laparoscopic partial nephrectomy with selective renal parenchymal clamping; T, transperitoneal; R, retroperitoneal; CCC, clear cell carcinoma; RCC, renal cell carcinoma; Lt, left; Rt, right; M, male; F, female. 1419Vol. 11 | No. 02 | March- April 2014 |U R O LO G Y J O U R N A L tive‎SF‎values‎were‎significantly‎decreased‎compared‎to‎the‎ preoperative‎values‎(39.7‎±‎6.5%‎vs.‎48.4‎±‎4.9%,‎P‎<‎.05).‎ On‎the‎other‎hand,‎mean‎postoperative‎SF‎in‎the‎non-affected‎ kidney‎was‎significantly‎increased‎compared‎with‎the‎preop- erative‎value‎(60.3‎±‎6.5%‎vs.‎51.3‎±‎4.5%,‎P‎<‎.05). Mean‎follow-ups‎for‎LPNSRPC‎and‎LPNMTC‎were‎14.5‎±‎ 9.3‎and‎17.2‎±‎4.8‎months,‎respectively‎(P =‎.568).‎Postop- erative‎CT‎was‎performed‎to‎screen‎for‎any‎recurrence‎every‎ 6‎ months.‎ However,‎ no‎ patient‎ demonstrated‎ local‎ recur- rence‎or‎distant‎metastasis‎during‎the‎follow-up‎period.‎In‎the‎ LPNSRPC‎group,‎postoperative‎CT‎did‎not‎show‎the‎bands‎ of‎ non-enhancing‎ renal‎ tissue‎ along‎ the‎ surgical‎ margins.‎ However,‎in‎the‎LPNMTC‎group,‎postoperative‎CT‎showed‎ bands‎of‎non-enhancing‎heat-damaged‎renal‎tissue‎measur- ing‎5‎to‎10‎mm‎in‎width‎along‎the‎surgical‎margins.‎ DISCUSSION As‎LPN‎gains‎widespread‎acceptance,‎there‎is‎a‎great‎need‎ for‎a‎novel‎surgical‎technique‎that‎is‎reliable‎and‎provides‎ bloodless‎resection‎of‎the‎renal‎parenchyma‎without‎damag- ing‎the‎residual‎renal‎tissue.‎There‎have‎traditionally‎been‎3‎ different‎technical‎strategies‎for‎LPN.‎ The‎complete‎renal‎ ischemic‎technique‎involves‎clamping‎ the‎renal‎vessels.‎However,‎a‎major‎concern‎is‎the‎duration‎of‎ renal‎ischemia‎after‎hilar‎clamping,‎which‎generally‎requires‎ 20-30‎min.‎Since‎this‎technique‎is‎very‎complex,‎including‎ complete‎tumor‎resection,‎ensuring‎hemostasis‎in‎the‎renal‎ parenchyma‎and‎intracorporeal‎freehand‎suture‎repair‎of‎the‎ pelvicalyceal‎system‎and‎approximation‎of‎the‎renal‎paren- chyma,‎it‎may‎not‎always‎be‎easy‎to‎perform‎LPN‎within‎the‎ limited‎warm‎ischemia‎time.‎It‎has‎been‎reported‎that‎if‎the‎ warm‎ischemia‎time‎is‎prolonged‎during‎LPN,‎the‎functional‎ damage‎to‎the‎affected‎kidney‎is‎progressive‎and‎can‎be‎ir- reversible.(9) In‎the‎non-ischemic‎technique,‎a‎variety‎of‎energy‎sources‎ may‎be‎used‎as‎an‎adjunctive‎measure‎to‎minimize‎hemor- rhage, including ultrasonic shears,(10) water-jet dissector,(11)‎ diode laser,(12)‎floating-ball‎radiofrequency‎dissector(13)‎and radiofrequency‎coagulation.(14)‎Resection‎of‎the‎tumor‎with- out‎inducing‎ischemia‎is‎feasible‎in‎small‎and‎peripherally‎ located‎renal‎masses.‎However,‎it‎can‎be‎difficult‎to‎obtain‎ adequate‎hemostasis‎and‎another‎possible‎major‎drawback‎ is‎collateral‎thermal‎damage‎to‎surrounding‎structures‎due‎to‎ excessive‎burning‎or‎charring‎of‎the‎tissue.‎ LPNSRPC‎permits‎normal‎blood‎perfusion‎of‎the‎unclamped‎ kidney‎during‎LPN.‎Thus,‎a‎major‎portion‎of‎the‎kidney‎is‎ spared‎from‎ischemia,‎which‎theoretically‎prevents‎the‎inher- ent‎problem‎of‎ischemic‎damage.‎However,‎LPNSRPC’s‎ef- fect‎on‎renal‎function‎is‎not‎well‎known‎and‎requires‎further‎ studies.(5,15,16) In‎the‎LPNSRPC‎group,‎GFR‎and‎SF‎in‎the‎affected‎kidney‎ were‎not‎significantly‎different‎postoperatively‎according‎to‎ renal‎ scanning.‎ Postoperative‎ CT‎ in‎ the‎ LPNSRPC‎ group‎ did‎ not‎ show‎ bands‎ of‎ non-enhancing‎ renal‎ tissue‎ along‎ the‎surgical‎margins,‎as‎opposed‎to‎in‎the‎LPNMTC‎group.‎ Furthermore,‎cold‎excision‎can‎be‎performed‎in‎a‎bloodless‎ operative‎field‎using‎this‎technique.‎Cold‎excision‎may‎mini- mize‎collateral‎thermal‎damage‎to‎the‎surrounding‎structures.‎ Moreover,‎during‎hemostasis,‎the‎jaw‎pressure‎can‎be‎tem- porarily‎reduced‎to‎better‎visualize‎the‎bleeding‎site,‎which‎ might‎prevent‎excessive‎burning‎or‎charring‎of‎the‎tissue.‎ The‎Simon‎clamp‎provides‎uniform‎and‎constant‎pressure‎ over‎the‎length‎of‎the‎jaws‎and‎is‎therefore‎unlikely‎to‎crush‎ the‎renal‎parenchyma.‎Although‎the‎clinical‎significance‎of‎ frozen-section‎analysis‎to‎evaluate‎resection‎margins‎during‎ PN‎is‎controversial,‎we‎routinely‎performed‎intraoperative‎ pathological‎consultation‎to‎ensure‎that‎we‎achieved‎nega- tive‎margins.‎Therefore,‎the‎mean‎selective‎clamping‎time,‎ Renal Parenchymal Clamping during Laparoscopic Partial Nephrectomy | Nozaki et al Table 2. The surgical outcomes. LPNMTC (n = 6) PNSRPC (n = 6) P Mean operative time (min) 209.1 ± 73.3 (105-326) 230.6 ± 38.9 (179-270) .540 Mean blood loss (mL) 26.6 ± 60.5 (0-150) 50.0 ± 45.1 (0-100) .84 Mean Hb decrease (g/dL) 0.5 ± 1.7 (0.1-2.6) 1.3 ± 0.7 (0.1-2.0) .48 Keys: LPNMTC, laparoscopic partial nephrectomy using microwave tissue coagulation; LPNSRPC, laparoscopic partial nephrectomy with selective renal parenchymal clamping; Hb, hemoglobin. 1420 | Laparoscopic Urology which‎included‎pathological‎consultation‎of‎a‎biopsy‎taken‎ from‎the‎tumor‎bed,‎was‎relatively‎prolonged‎in‎comparison‎ to‎ other‎ clinical‎ reports‎ of‎ LPNSRPC.(16)‎ Our‎ study‎ find- ings‎ indicated‎ that‎ prolonged‎ parenchymal‎ clamping‎ does‎ not‎impair‎the‎postoperative‎renal‎function‎of‎the‎affected‎ kidney.‎Therefore,‎our‎preliminary‎results‎demonstrated‎that‎ LPNSRPC‎preserved‎the‎maximum‎renal‎function‎of‎the‎af- fected‎kidney.‎In‎particular,‎LPNSRPC‎would‎be‎preferable‎ for‎patients‎with‎pre-existing‎renal‎impairment‎and‎elderly‎ patients. Additional studies, including larger cohorts, are needed to support our results. In‎Japan,‎MTC‎is‎widely‎used‎in‎non-ischemic‎LPN.(17,18)‎ In‎our‎series,‎SF‎in‎the‎affected‎kidneys‎of‎the‎LPNMTC‎ group‎were‎significantly‎decreased‎postoperatively,‎accord- ing‎to‎the‎renal‎scan.‎In‎addition,‎postoperative‎CT‎showed‎ bands‎of‎non-enhancing‎heat-damaged‎renal‎tissue‎measur- Table 3. Preoperative and postoperative renal function data of LPNSRPC and LPNMTC. Variables LPNMTC (n = 6) P LPNSRPC (n = 6) P Mean serum creatinine (mg/dL) .732* Preoperative 0.88 ± 0.16 (0.7-1.1) 0.96 ± 0.91 (0.5-2.8) .750** .250** Postoperative 0.92 ± 0.21 (0.8-1.3) .676* Renal Scan data Total Kidney .984* Mean preoperative GFR 77.0 ± 25.7 (48.3-111.8) 77.3 ± 37.9 (14.5-124.3) .843** .062** Mean postoperative GFR 74.9 ± 21.0 (50.7-102.8) 90.6 ± 55.7 (17.7-137.5) .424* The affected kidney Mean preoperative GFR 36.8 ± 10.8 (25.2-51.8) 38.7 ± 17.7 (8.9-9.0) .093** .562** Mean postoperative GFR 29.6 ± 8.8 (16.5-40.2) 41.4 ± 18.5 (11.9-61.1) .191* .268* Mean preoperative SF 48.4 ± 4.9 (38.8-52.1) 51.9 ± 5.3 (47.5-61.4) < .05** .312 Mean postoperative SF 39.7 ± 6.5 (31.8-47.8) 48.8 ± 9.8 (43.4-67.1) .089* The non-affected kidney .891* Mean preoperative GFR 40.1 ± 16.3 (23.1-16.3) 38.6 ± 20.4 (5.6-65.3) .218** < .05 Mean postoperative GFR 45.2 ± 13.9 (29.8-62.6) 48.3 ± 23.7 (5.8-77.8) .793* .274* Mean preoperative SF 51.3 ± 4.5 (47.9-60.2) 48.0 ± 5.3 (38.6-53.2) < .05** .311 Mean postoperative SF 60.3 ± 6.5 (52.2-68.2) 51.2 ± 9.8 (32.9-61.1) .089* Keys: LPNMTC, laparoscopic partial nephrectomy using microwave tissue coagulation; LPNSRPC, laparoscopic partial nephrectomy with selective renal parenchymal clamping; GFR, glomerular filtration rate; SF, split function. * LPNMTC vs. LPNSRPC. ** Preoperative vs. postoperative. 1421Vol. 11 | No. 02 | March- April 2014 |U R O LO G Y J O U R N A L REFERENCES 1. Uzzo RG, Novick AC. Nephron sparing surgery for renal tumors: in- dications, techniques and outcomes. J Urol. 2001;166:6-18. 2. Abukora F, Nambirajan T, Albqami N, et al. Laparoscopic nephron sparing surgery: evolution in a decade. Eur Urol. 2005;47:488-93. 3. Zini L, Patard JJ, Capitanio U, et al. Cancer-specific and non-cancer- related mortality rates in European patients with T1a and T1b renal cell carcinoma. BJU Int. 2009;103:894-8. Renal Parenchymal Clamping during Laparoscopic Partial Nephrectomy | Nozaki et al ing‎5‎to‎10‎mm‎in‎width‎along‎the‎surgical‎margins.‎Nanri‎ and‎colleagues‎suggested‎that‎renal‎damage‎induced‎by‎MTC‎ comprises‎ not‎ only‎ necrosis‎ but‎ also‎ apoptotic‎ changes.‎ When‎performing‎the‎LPNMTC,‎it‎must‎be‎considered‎that‎ renal‎thermal‎damage‎caused‎by‎MTC‎may‎spread‎beyond‎ the‎surgeon’s‎expectations.(19)‎On‎the‎other‎hand,‎SF‎in‎the‎ non-affected‎kidney‎was‎significantly‎increased.‎Therefore,‎ the‎renal‎function‎of‎the‎non-affected‎kidney‎might‎compen- sate‎for‎dysfunction‎on‎the‎affected‎kidney,‎postoperatively.‎ Furthermore,‎a‎tumor‎in‎contact‎with‎the‎collecting‎system‎ would‎be‎unresectable‎using‎this‎technique,‎because‎sutur- ing‎the‎renal‎pelvic‎mucosa‎can‎be‎difficult‎after‎coagulation‎ using‎the‎MTC.‎LPNMTC‎can‎be‎one‎of‎the‎useful‎modali- ties‎for‎the‎treatment‎of‎renal‎tumor‎because‎of‎its‎technical‎ feasibility‎and‎adequate‎hemostasis.‎However,‎the‎surgeon‎ must‎bear‎in‎mind‎that‎the‎MTC‎could‎cause‎heat-induced‎ apoptosis‎over‎unexpectedly‎wide‎area. With‎the‎exception‎of‎clamping‎the‎renal‎artery,‎the‎remaining‎ surgical‎procedure‎of‎the‎LPNSRPC‎is‎similar‎to‎LPN‎with‎is- chemia,‎including‎complete‎resection‎of‎the‎renal‎tumor,‎hemo- stasis‎from‎the‎renal‎parenchyma,‎and‎intracorporeal‎freehand‎ suture‎repair‎of‎the‎pelvicalyceal‎system‎and‎approximation‎of‎ the‎renal‎parenchyma.‎We‎recommend‎that‎LPNSRPC‎should‎ be‎performed‎by‎highly‎experience‎surgeons‎with‎skills‎in‎lap- aroscopic‎suture.‎In‎comparison‎with‎LPN‎with‎ischemia,‎the‎ Simon‎clamp‎grasps‎the‎entire‎kidney,‎and‎therefore,‎it‎is‎nec- essary‎to‎fully‎mobilize‎the‎kidney‎even‎within‎the‎confines‎of‎ the‎limited‎space.‎The‎direction‎and‎angle‎of‎the‎kidney‎could‎ be‎easily‎changed‎in‎a‎timely‎manner,‎thus‎facilitating‎precise‎ tumor‎excision‎and‎intracorporeal‎freehand‎suture‎without‎any‎ hurry‎or‎fear‎of‎renal‎ischemia.‎ LPNSRPC‎ has‎ several‎ limitations.‎ First,‎ this‎ technique‎ cannot‎be‎applied‎to‎central‎or‎hilar‎tumors‎because‎of‎the‎ impossibility‎of‎placing‎the‎clamp.‎This‎technique‎is‎better‎ suited‎for‎polar‎tumors‎or‎small‎exophytic‎tumors‎located‎on‎ the‎lateral‎convexity‎of‎the‎kidney‎where‎some‎degree‎of‎is- chemia‎occurs‎in‎the‎normal‎tissue‎also.‎Second,‎incomplete‎ regional‎ischemia‎may‎cause‎excessive‎bleeding‎during‎LPN.‎ Therefore,‎special‎consideration‎should‎be‎given‎to‎the‎ideal‎ trocar‎location‎for‎clamp‎placement‎to‎minimize‎ischemic‎ damage‎during‎LPN.‎Viprakasit‎and‎colleagues‎reported‎that‎ incomplete‎clamp‎compression‎at‎the‎distal‎aspect‎in‎3‎cases‎ resulted‎in‎excessive‎bleeding‎and‎decreased‎visualization,‎ necessitating‎parenchymal‎clamp‎removal‎and‎placement‎of‎a‎ central‎hilar‎clamp‎to‎complete‎the‎procedure.(16)‎Keeping‎the‎ renal‎pedicle‎with‎vessel‎tape‎is‎recommended‎for‎safe‎com- pletion‎of‎LPNSRPC,‎especially‎during‎the‎learning‎curve.‎ It‎allows‎rapid‎application‎of‎laparoscopic‎bulldog‎clamps‎ if‎bleeding‎should‎preclude‎safe‎LPNSRPC.‎Flexibility‎with‎ regard‎to‎the‎conversion‎to‎LPN‎with‎ischemia‎is‎necessary‎ in‎cases‎with‎difficulty‎in‎complete‎clamp‎compression‎or‎ unmanageable‎ bleeding.‎ Careful‎ anatomical‎ evaluation‎ of‎ the‎lesion‎is‎essential‎for‎operative‎success.‎Third,‎our‎study‎ has‎a‎small‎number‎of‎patients,‎and‎this‎is‎a‎limitation‎for‎ this‎study.‎The‎present‎study‎would‎have‎been‎enhanced‎by‎a‎ larger‎series‎of‎patients‎to‎demonstrably‎prove‎the‎efficacy‎of‎ this‎technique‎and‎its‎advantages,‎including‎reduced‎bleed- ing,‎maximum‎preservation‎of‎renal‎function‎in‎the‎affected‎ kidney,‎and‎reduced‎operative‎time.‎Although‎we‎are‎encour- aged‎by‎the‎preliminary‎findings‎of‎our‎experience,‎it‎was‎ only‎assessed‎the‎superiority‎of‎LPNSRPC‎when‎compared‎ with‎LPNMTC‎in‎early‎postoperative‎period.‎Recently,‎off- clamp,(20)‎or‎zero-ischemia‎approach‎to‎LPN(21) has been a proposed‎means‎of‎preserving‎global‎renal‎function‎by‎pre- venting‎ischemia‎to‎normal‎renal‎parenchyma.‎Further‎stud- ies,‎in‎addition‎to‎a‎comparison‎of‎other‎LPN‎technique,‎such‎ as‎zero-ischemia‎approach‎to‎LPN,‎are‎necessary‎to‎delineate‎ what,‎if‎any‎specific‎advantages‎may‎lie‎with‎the‎LPNSRPC.‎ CONCLUSION In‎this‎study,‎we‎describe‎our‎experience‎with‎LPN‎using‎ the‎laparoscopic‎Simon‎clamp‎to‎induce‎selective‎regional‎ ischemia,‎without‎renal‎hilar‎clamping,‎and‎Tc-99m‎DTPA‎ scanning‎ to‎ compare‎ preoperative‎ and‎ postoperative‎ renal‎ function.‎In‎carefully‎selected‎patients‎with‎tumors‎in‎ideal‎ locations‎for‎LPNSRPC,‎we‎recommend‎this‎non-ischemic‎ technique‎for‎maximum‎nephron-sparing‎surgery. CONFLICT OF INTEREST None declared. 1422 | 4. Hollingsworth JM, Miller DC, Daignault S, Hollenbeck BK. Rising in- cidence of small renal masses: a need to reassess treatment effect. J Natl Cancer Inst. 2006;98:1331-4. 5. Simon J, Bartsch G, Finter F, Hautmann R, de Petriconi R. Laparo- scopic partial nephrectomy with selective control of the renal pa- renchyma: Initial experience with a novel laparoscopic clamp. BJU Int. 2008;103:8805-8. 6. Assadi M, Eftekhari M, Hozhabrosadati M, et al. Comparison of methods for determination of glomerular filtration rate: low and high-dose Tc-99m-DTPA renography, predicted creatinine clear- ance method, and plasma sample method. Int Urol Nephrol. 2008;40:1059-65. 7. Yasui T, Itoh Y, Kojima Y, et al. Impact of microwave tissue coagu- lation during laparoscopic partial nephrectomy on postoperative renal function. Int Urol Nephrol. 2008;40:277-82. 8. Kutikov A, Uzzo RG. The R.E.N.A.L. nephrometry score: a compre- hensive standardized system for quantitating renal tumor size, lo- cation and depth. J Urol. 2009;182:844-53. 9. Choi JD, Park JW, Lee SY, et al. Does prolonged warm ischemia after partial nephrectomy under pneumoperitoneum cause irreversible damage to the affected kidney? J Urol. 2012;187:802-6. 10. Harmon WJ, Kavoussi LR, Bishoff JT. Laparoscopic nephron-sparing surgery for solid renal masses using the ultrasonic shears. Urology. 2000;56:754-9. 11. Moinzadeh A, Hasan W, Spaliviero M, et al. Water jet assisted lapa- roscopic partial nephrectomy without hilar clamping in the calf model. J Urol. 2005;174:317-21. 12. Ogan K, Jacomides L, Saboorian H, et al. Sutureless laparoscop- ic heminephrectomy using laser tissue soldering. J Endourol. 2003;17:295-300. 13. Sundaram CP, Rehman J, Venkatesh R, et al. Hemostatic laparo- scopic partial nephrectomy assisted by a water-cooled, high-den- sity, monopolar device without renal vascular control. Urology. 2003;61:906-9. 14. Zeltser IS, Moonat S, Park S, Anderson JK, Cadeddu JA. Intermediate- term prospective results of radiofrequency-assisted laparoscopic partial nephrectomy: a non-ischaemic coagulative technique. BJU Int. 2008;101:36-8. 15. Viprakasit DP, Altamar HO, Miller NL, Herrell SD. Selective renal pa- renchymal clamping in robotic partial nephrectomy: Initial experi- ence. Urology. 2010;76:750-3. 16. Viprakasit DP, Derweesh I, Wong C, et al. Selective renal parenchy- mal clamping in robot-assisted laparoscopic partial nephrectomy: a multi-institutional experience. J Endourol. 2011;25:1487-91. 17. Terai A, Ito N, Yoshimura K, et al. Laparoscopic partial nephrectomy using microwave tissue coagulator for small renal tumors: useful- ness and complications. Eur Urol. 2004;45:744-8. 18. Furuya Y, Tsuchida T, Takihana Y, et al. Retroperitoneoscopic nephron-sparing surgery of renal tumor using a microwave tissue coagulator without renal ischemia: comparison with open proce- dure. J Endourol. 2003;17:53-8. 19. Nanri M, Udo K, Kawasaki M, et al. Microwave tissue coagulator in- duces renal apoptotic damage to preserved normal renal tissue fol- lowing partial nephrectomy. Clin Exp Nephrol. 2009;13:424-9. 20. Rais-Bahrami S, George AK, Herati AS, Srinivasan AK, Richstone L, Kavoussi LR. Off-clamp versus complete hilar control laparo- scopic partial nephrectomy: comparison by clinical stage. BJU Int. 2012;109:1376-81. 21. Rizkala ER, Khalifeh A, Autorino R, Samarasekera D, Laydner H, Ka- ouk JH. Zero ischemia robotic partial nephrectomy: sequential pre- placed suture renorrhaphy technique. Urology. 2013;82:100-4. Laparoscopic Urology