The Road to Real Zero Ischemia for Partial Nephrectomy

Acute Kidney Injury after Partial Nephrectomy of Solitary Kidneys: Impact on Long-Term Stability of Renal Function

PURPOSE

Acute kidney injury often leads to chronic kidney disease in the general population. The long-term functional impact of acute kidney injury observed after partial nephrectomy has not been adequately studied.

MATERIALS AND METHODS

From 2004 to 2014 necessary studies for analysis were available for 90 solitary kidneys managed by partial nephrectomy. Functional data at 4 time points included preoperative serum creatinine, peak postoperative serum creatinine, new baseline serum creatinine 3 to 12 months postoperatively and long-term followup serum creatinine more than 12 months postoperatively. Adjusted acute kidney injury was defined by the ratio, observed peak postoperative serum creatinine/projected postoperative serum creatinine adjusted for parenchymal mass loss to reveal the true effect of ischemia. The long-term change in renal function (the long-term functional change ratio) was defined as the most recent glomerular filtration rate/the new baseline glomerular filtration rate. The relationship between the grade of the adjusted acute kidney injury and the long-term functional change was assessed by Spearman correlation analysis and multivariable regression.

RESULTS

Median patient age was 64 years and median followup was 45 months. Median parenchymal mass preservation was 80%. Adjusted acute kidney injury occurred in 42% of patients, including grade 1 injury in 20 (22%) and grade 2/3 in 18 (20%). On univariable analysis the degree of the adjusted acute kidney injury did not correlate with the long-term glomerular filtration rate change (p = 0.55). On multivariable analysis adjusted acute kidney injury was not associated with a long-term functional change (p >0.05) while diabetes and warm ischemia were modestly associated with a long-term functional decline (each p <0.05).

CONCLUSIONS

Acute kidney injury after partial nephrectomy was not a significant or independent predictor of long-term functional decline in our institutional cohort. A prospective study with larger sample sizes and longer followup is required to evaluate factors associated with long-term nephron stability.

Off-Clamp Renal Tumourectomy by Retroperitoneoscopy in Posterior Renal Tumours of Medium Complexity (Padua score 8-9)

BACKGROUND

The guidelines recommend partial surgery for T1 renal tumours. Various aspects of this surgery have evolved in recent years, including the clamping method and duration, enucleation, the retroperitoneoscopic approach and the use of 3mm ports. We present our initial series on laparoscopic renal tumourectomy by retroperitoneoscopy (LRTR) and analyse our learning curve and use of 3-mm instrumentation.

MATERIAL AND METHODS

From January 2011 to January 2015, we performed LRTR on 50 patients with posterior or convex T1 renal tumours. After 10 cases, the technique changed to off-clamp, and 11 cases were subsequently performed with 3mm instrumentation.

RESULTS

The mean tumour size was 34.36 mm (14-62), with a mean PADUA score of 8.42 (5-12). The mean operative time was 163.1 minutes (75-300), and the mean warm ischaemia time was 4.21 minutes (0-28). The main renal artery was not clamped in 41 (82%) patients, and no vessel (zero ischaemia) was clamped in 39 (78%) patients. Seven cases had positive margins (6 focal). Eleven LRTRs were performed with 3mm instrumentation, with shorter surgical times, less intraoperative bleeding and shorter hospital stays.

CONCLUSIONS

Retroperitoneoscopy coupled with enucleation enables the extirpation without clamping of posterior renal tumours, with a relatively short learning curve. The 3-mm material enables the technique to be performed, although in our experience it has resulted in a higher rate of positive surgical margins.

Residual Parenchymal Volume, Not Warm Ischemia Time, Predicts Ultimate Renal Functional Outcomes in Patients Undergoing Partial Nephrectomy

OBJECTIVE

To examine relative contributions of functional parenchymal preservation and renal ischemia following nephron-sparing surgery (NSS). While residual functional parenchymal volume (FPV) is proposed as the key factor in predicting functional outcomes following NSS, efforts to curtail ischemia time continue to add technical complexity to partial nephrectomy.

METHODS

Our kidney cancer database was queried for patients who underwent NSS with warm ischemia time (WIT). Patients with cross-sectional imaging for FPV calculation were included. Cylindrical volume approximation methodology was used to calculate FPV, accounting for the volume of tumor's endophytic component. Percent estimated glomerular filtration rate (eGFR) preservation, perioperatively and at 6 months, was the outcome metric. Spearman correlation and linear regression analyses were used to evaluate associations of WIT and %FPV preservation with renal function preservation.

RESULTS

Of the 179 patients included, median preoperative eGFR was 88.4 (9.5% chronic kidney disease III or IV), tumor size was 2.7 cm (interquartile range [IQR] 2.0-3.6 cm), and R.E.N.A.L. nephrometry was low in 34%, intermediate in 57%, and high in 9%. Median WIT was 30 minutes (IQR 24-36), resulting in 97.4% FPV preservation. Median postoperative eGFR at 6.4 months was 80.5 (19.1% chronic kidney disease III or IV), a median of 93.1% eGFR preservation (IQR 85.1-101.7). At discharge, WIT (P <.001), not %FPV (P = .112), was associated with %eGFR preservation. However, 6 months following surgery, on multivariable analysis, both preoperative eGFR (linear regression coefficient = -0.208, P = .006) and %FPV preservation (linear regression coefficient = 0.491, P = .001), but not WIT (P = .946), demonstrated statistically significant association with %eGFR preservation.

CONCLUSION

Residual FPV, and not WIT, appears to be the main predictor of ultimate renal function following NSS.

Zero ischemia robotic-assisted partial nephrectomy in Alberta: Initial results of a novel approach

INTRODUCTION

Partial nephrectomy remains the standard of care in early stage, organ-confined renal tumours. Recent evidence suggests that minimally invasive surgery can proceed without segmental vessel clamping. In this study, we review our experience at a Canadian centre with zero ischemia robotic-assisted partial nephrectomy (RAPN).

METHODS

A retrospective chart review of zero ischemia RAPN was performed. All surgeries were consecutive partial nephrectomies performed by the same surgeon at a tertiary care centre in Northern Alberta. The mean follow-up period was 28 months. These outcomes were compared against the current standards for zero ischemia (as outlined by the University of Southern California Institute of Urology [USC]).

RESULTS

We included 21 patients who underwent zero ischemia RAPN between January 2012 and June 2013. Baseline data were similar to contemporary studies. Twelve (57.1%) required no vascular clamping, 7 (33.3%) required clamping of a single segmental artery, and 2 (9.5%) required clamping of two segmental arteries. We achieved an average estimated blood loss of 158 cc, with a 9.2% average increase in creatinine postoperatively. Operating time and duration of hospital stay were short at 153 minutes and 2.2 days, respectively.

CONCLUSION

Zero ischemia partial nephrectomy was a viable option at our institution with favourable results in terms of intra-operative blood loss and postoperative creatinine change compared to results from contemporary standard zero ischemia studies (USC). To our knowledge, this is the first study to review an initial experience with the zero ischemia protocol in robotic-assisted partial nephrectomies at a Canadian hospital.

ZIRK-Technique: Zero Ischemia Resection in the Kidney for High-Risk Renal Masses: Perioperative Outcome

OBJECTIVES

This study evaluates the feasibility and safety of open-partial nephrectomies in the ZIRK-technique (Zero Ischemia Resection in the Kidney) for renal masses with high-risk anatomical features--objectified by the PADUA score.

METHODS

We identified 40 consecutive cases of partial nephrectomies performed without clamping of the renal artery in our department of urology. Retrospective analysis of the preoperative CT or MRI scans showed 27 cases with a PADUA score ≥8, of which 15 cases had a score ≥10. Cases were in particular assessed regarding operation time (ORT), estimated blood loss (EBL), surgical margins and postoperative complications using the Clavien classification.

RESULTS

The mean age of the study population was 67.6 years with an average BMI of 26.8 kg/m2. The mean ORT was 1:46 with an average EBL of 521 ml. Clavien grade II complications were observed seven times, while 3 patients had a grade IIIa complication. Despite complex and adverse location of the tumors, nephron-sparing surgery without ischemia could be performed with negative surgical margins for all cases. EBL, transfusion rate and complication were considerably more frequent in high-risk tumors.

CONCLUSION

Highly complex renal tumors, PADUA ≥10, can be resected in ZIRK-technique with good operative outcome and a low complication rate.