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.

Design, setting, and participants: 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).

Surgical procedure: 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.

Outcome measurements and statistical analysis: 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.

Results and limitations: 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.

Patient summary: 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.

Keywords: Enucleation; Minimal margin; Renal cell carcinoma; Robotic partial nephrectomy; Small renal mass; Unclamped partial nephrectomy; Zero ischemia.