title: Robotic unclamped "minimal-margin" partial nephrectomy: ongoing refinement of the anatomic zero-ischemia concept.
abstract: BACKGROUND
  Anatomic partial nephrectomy (PN) techniques aim to decrease or eliminate global renal ischemia.
  
  
  OBJECTIVE
  To report the technical feasibility of completely unclamped "minimal-margin" robotic PN. We also illustrate the stepwise evolution of anatomic PN surgery with related outcomes data.
  
  
  METHODS
  This study was a retrospective analysis of 179 contemporary patients undergoing anatomic PN at a tertiary academic institution between October 2009 and February 2013. Consecutive consented patients were grouped into three cohorts: group 1, with superselective clamping and developmental-curve experience (n = 70); group 2, with superselective clamping and mature experience (n = 60); and group 3, which had completely unclamped, minimal-margin PN (n = 49).
  
  
  METHODS
  Patients in groups 1 and 2 underwent superselective tumor-specific devascularization, whereas patients in group 3 underwent completely unclamped minimal-margin PN adjacent to the tumor edge, a technique that takes advantage of the radially oriented intrarenal architecture and anatomy.
  
  
  METHODS
  Primary outcomes assessed the technical feasibility of robotic, completely unclamped, minimal-margin PN; short-term changes in estimated glomerular filtration rate (eGFR); and development of new-onset chronic kidney disease (CKD) stage >3. Secondary outcome measures included perioperative variables, 30-d complications, and histopathologic outcomes.
  
  
  CONCLUSIONS
  Demographic data were similar among groups. For similarly sized tumors (p = 0.13), percentage of kidney preserved was greater (p = 0.047) and margin width was narrower (p = 0.0004) in group 3. In addition, group 3 had less blood loss (200, 225, and 150ml; p = 0.04), lower transfusion rates (21%, 23%, and 4%; p = 0.008), and shorter hospital stay (p = 0.006), whereas operative time and 30-d complication rates were similar. At 1-mo postoperatively, median percentage reduction in eGFR was similar (7.6%, 0%, and 3.0%; p = 0.53); however, new-onset CKD stage >3 occurred less frequently in group 3 (23%, 10%, and 2%; p = 0.003). Study limitations included retrospective analysis, small sample size, and short follow-up.
  
  
  CONCLUSIONS
  We developed an anatomically based technique of robotic, unclamped, minimal-margin PN. This evolution from selective clamped to unclamped PN may further optimize functional outcomes but requires external validation and longer follow-up.
  
  
  RESULTS
  The technical evolution of partial nephrectomy surgery is aimed at eliminating global renal damage from the cessation of blood flow. An unclamped minimal-margin technique is described and may offer renal functional advantage but requires long-term follow-up and validation at other institutions.
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Raj
authors.initials: R
authors.lastname: Satkunasivam
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Sheaumei
authors.initials: S
authors.lastname: Tsai
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Sumeet
authors.initials: S
authors.lastname: Syan
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Bernhard
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Andre Luis
authors.initials: AL
authors.lastname: de Castro Abreu
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Chopra
authors.affiliation: Department of Urology, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Andre K
authors.initials: AK
authors.lastname: Berger
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Lee
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hung
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Cai
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Mihir M
authors.initials: MM
authors.lastname: Desai
authors.affiliation: USC Institute of Urology, Catherine and Joseph Aresty Department of Urology, University of Southern California, Los Angeles, CA, USA. Electronic address: gillindy@gmail.com.
authors.forename: Inderbir S
authors.initials: IS
authors.lastname: Gill
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000098:blood supply / Q000473:pathology / Q000601:surgery*; D003250:Constriction; D005240:Feasibility Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007511:Ischemia; D007680:Kidney Neoplasms / Q000098:blood supply / Q000473:pathology / Q000601:surgery*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects / Q000379:methods*; D061646:Operative Time; D012077:Renal Artery / Q000503:physiopathology / Q000601:surgery*; D012079:Renal Circulation; D051436:Renal Insufficiency, Chronic / Q000209:etiology / Q000503:physiopathology; D012189:Retrospective Studies; D012307:Risk Factors; D065287:Robotic Surgical Procedures; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult
keywords: Enucleation; Minimal margin; Renal cell carcinoma; Robotic partial nephrectomy; Small renal mass; Unclamped partial nephrectomy; Zero ischemia