Elsevier

European Urology

Volume 68, Issue 4, October 2015, Pages 705-712
European Urology

Surgery in Motion
Robotic Unclamped “Minimal-margin” Partial Nephrectomy: Ongoing Refinement of the Anatomic Zero-ischemia Concept

https://doi.org/10.1016/j.eururo.2015.04.044Get rights and content

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 150 ml; 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.

Introduction

The role of partial nephrectomy (PN) in the management of small renal masses (SRMs) remains controversial; however, the significant prevalence of chronic kidney disease (CKD) and its associated morbidity argue in favor of nephron-sparing approaches [1], [2], [3], [4]. The adoption of laparoscopic and robotic PN has been propelled by equivalent oncologic and functional outcomes compared with the open approach [5].

Recent technical refinements have been aimed at optimizing surgically modifiable factors, such as warm ischemia, starting initially with early unclamping and subsequently with selective segmental artery clamping [6], [7], [8], [9]. We described an anatomic PN technique aimed at tumor-specific devascularization, with the goal of eliminating global ischemia to the renal remnant [6]. The goals of further minimizing functional parenchymal loss and altogether eliminating global renal ischemia remain. The primary aim of this paper is to describe the technical feasibility and early outcomes of completely unclamped, “minimal-margin,” robotic PN. To place this in the context of overall stepwise evolution of our anatomic PN approach, we also evaluated the impact of this technical progression on perioperative outcomes.

Section snippets

Study population

From October 2009 to February 2013, 320 patients with renal tumors underwent minimally invasive PN by a single surgeon, and 208 (65%) of those patients underwent anatomic PN surgery. Patient selection for anatomic PN was at the discretion of the operating surgeon. A total of 179 patients consented to have their data prospectively collected in our institutional review board–approved database and compose the study cohort. Preoperative workup included clinical and laboratory evaluation and

Results

Anatomic PN was performed in 179 patients who were retrospectively divided into three groups based on operative technique. The groups were comparable in terms of age, sex, body mass index, and comorbidities (Table 1). Baseline renal function was also similar among the groups, including incidence of CKD stage ≥3 (23–26%, p = 0.95). Nearly 10% of patients in each group had a solitary kidney. Median tumor size on CT was similar across groups (3.0 cm [range: 0.9–13.6], 3.4 cm [range: 1.3–7.9], 3.4 cm

Discussion

In this study, we examined the careful technical evolution of anatomic robotic PN from superselective clamping after vascular microdissection toward a completely unclamped approach. These data are in keeping with our earlier observation of functional benefits stemming from reducing or eliminating global renal ischemia. Specifically, volume-adjusted renal functional outcomes improved significantly as we progressed from conventional hilar clamping to early unclamping to superselective techniques

Conclusions

Our findings support the safety and feasibility of anatomic PN throughout its technical evolution. In addition, the unclamped minimal-margin technique may reduce intraoperative blood loss and yield superior early functional outcomes.

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These authors contributed equally.

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