The Volume of Nonneoplastic Parenchyma in a Minimally Invasive Partial Nephrectomy Specimen: Predictive Factors and Impact on Renal Function

Comparison of off-clamp microwave scissors-based sutureless partial nephrectomy versus on-clamp conventional partial nephrectomy in a canine model

Objectives

To compare the usefulness and safety of off-clamp microwave scissors-based sutureless partial nephrectomy (MSPN) with on-clamp conventional partial nephrectomy (cPN) in dogs.

Methods

We performed off-clamp MSPN using microwave scissors (MWS) in six dogs, and on-clamp cPN in three dogs, in two-stage experiments. The bilateral kidney upper poles were resected via a midline incision under general anesthesia. After 14 days of follow-up, the lower pole resections were performed. The renal calyces exposed during renal resections were sealed and transected using MWS in off-clamp MSPN and were sutured in on-clamp cPN. In the off-clamp MSPN group, the generator's power output of MWS was set as either 50 W or 60 W for each kidney side. We compared the procedure time (PT), ischemic time (IT), blood loss (BL), and normal nephron loss (NNL) between the two techniques using the Mann-Whitney U-test.

Results

We successfully performed 24 off-clamp MSPNs and 12 on-clamp cPNs. The off-clamp MSPN was significantly superior to on-clamp cPN in avoiding renal ischemia (median IT, 0 min vs. 8.6 min, p < 0.001) and reducing PT (median PT, 5.8 min vs. 11.5 min, p < 0.001) and NNL (median NNL, 5.3 mm vs. 6.0 mm, p = 0.006) with comparable BL (median BL, 20.9 ml vs. 23.2 ml, p = 0.804). No bleeding and major urine leakage were noted during the reoperations.

Conclusions

Off-clamp MSPN outperforms on-clamp cPN in lowering the risks of postoperative renal function impairment in dogs.

Parenchymal Mass Loss During Partial Nephrectomy: Role of Devascularized Parenchymal Mass and Excised Parenchymal Mass and Impact on Functional Preservation

This study included 93 patients with renal masses who underwent standard partial nephrectomy or tumor enucleation. After surgery, parenchymal mass loss caused by devascularization resulted in more damage to renal function than excised parenchymal mass loss. Surgeons should seek better techniques to decrease devascularization during reconstruction.

INTRODUCTION

To evaluate the importance of devascularized parenchymal mass(DPM) and excised parenchymal mass(EPM) in functional preservation after standard partial nephrectomy(SPN).

PATIENTS AND METHODS

Forty-one patients who underwent pure tumor enucleation(TE) and 52 patients who underwent SPN with necessary data were included. As no EPM was lost in TE, the TE samples were used to estimate the degree of volume shrinkage that occurred when the measurements were performed in vivo with blood flow versus ex vivo without, and the shrinkage ratio was calculated as specimen volume divided by tumor volume in vivo. In SPN, the specimen volume comprised tumor volume plus EPM. The EPM was calculated as specimen volume divided by shrinkage ratio minus tumor volume in vivo. The DPM was defined as total ipsilateral parenchymal mass loss minus EPM. T tests, χ² test, and Mann-Whitney U tests were employed to compare clinical characteristics. Multivariate analysis was used to identify variables that correlated with glomerular filtration rate(GFR) preservation.

RESULTS

The mean sizes of devascularized and excised parenchymal masses were 13.6 cm³ and 5.2 cm³ (P = .01), which accounted for 7.8% and 3.4% of preoperative ipsilateral parenchymal mass (P = .03) in SPN, respectively. The shrinkage ratio was 0.71 and correlation coefficient was 0.965. After stepwise regression, DPM, and preoperative GFR were significantly associated with global GFR preservation.

CONCLUSION

The DPM comprises most of parenchymal mass loss after SPN and plays a more important role than EPM on functional outcomes. Surgeons should pay more attention to reducing devascularization during partial nephrectomy.

Off-clamp tumor excision using soft coagulation in laparoscopic and robotic partial nephrectomy

INTRODUCTION

The aim of this study was to assess the perioperative outcomes of off-clamp tumor excision using soft coagulation in laparoscopic and robotic partial nephrectomy.

METHODS

We retrospectively analyzed the data from 78 patients who underwent minimally invasive partial nephrectomy, using soft coagulation, at the Shiga University of Medical Science, between September 2013 and April 2017. Tumor excision and hemostasis without renal arterial clamping was performed using soft coagulation. Collecting system repair and renorrhaphy with arterial clamping were carried out only if the collecting system had been opened.

RESULTS

Forty-three of the 78 patients underwent laparoscopic partial nephrectomy using soft coagulation and the other 35 patients underwent robotic partial nephrectomy using soft coagulation. The median estimated total blood loss was 73 (0-1140) mL and no patient needed a blood transfusion. No cases featured postoperative hemorrhagic events. Six patients with urinary fistula needed prolonged ureteral stenting. The median percentage change of the estimated glomerular filtration rate was -7.2 at one to 3 months after surgery.

CONCLUSION

The off-clamp soft coagulation technique in laparoscopic partial nephrectomy and robotic partial nephrectomy is a safe and feasible approach to excise kidney tumors. This procedure may reduce the incidence of perioperative hemorrhagic complications.

Determinants and Implications of Excised Parenchymal Mass on Robotic-Assisted Partial Nephrectomy Outcomes

OBJECTIVES

To evaluate the association between excised parenchymal mass (EPM) and postoperative renal function (eGFR) following robotic-assisted partial nephrectomy (RAPN). EPM is the amount of healthy renal parenchyma excised during partial nephrectomy in order to achieve safe surgical margins.

METHODS

We evaluated 406 consecutive RAPN performed by a single surgeon to eliminate variations in technique as a factor in EPM. EPM (mL) = (specimen volume * π/6) - (tumor volume * π/6). RENAL score was categorized as easy (4-6), moderate (7-9), or hard (10-12). EPM was grouped into four categories: ≤ 3.9 mL, 4.0-9.9 mL, 10.0-17.7 mL, and >17.7 mL. eGFR was evaluated preoperatively, postoperative day 1 (POD1), 1 month, and 6 months postoperatively.

RESULTS

Median age was 63 years (22-84 years), 252 (62.1%) were male, and median EPM was 9.9 mL (interquartile range 3.9 to 17.7 mL). The median EPM and interquartile range for each RENAL category was 3.7 mL (2.0, 7.9), 12 mL (5.7, 19.4), and 16.2 mL (7.9, 24.3), respectively. Higher EPM was associated with worse changes in eGFR at POD1 (P = 0.005) and 1 month after RAPN (P = 0.002) but was not statistically significant at the 6-month time period (P = 0.35) CONCLUSION: Increased tumor complexity is associated with an increase in EPM during RAPN. Increased EPM is associated with eGFR decline at POD1 and 1 month post RAPN but not at 6 months postoperatively.

Assessment of Advanced Perioperative Outcomes to Identify the True Learning Curve of Robotic-assisted Partial Nephrectomy

OBJECTIVES

To evaluate the learning curve of robotic-assisted partial nephrectomy as it pertains to operative time (OT) and advanced perioperative variables such as achievement of trifecta, postoperative complications, 30-day readmission rates (RR), warm ischemia time (WIT), and functional volume loss (FVL).

METHODS

We evaluated 418 consecutive robotic-assisted partial nephrectomy performed by a single surgeon between February 2008 and April 2019. Multivariable log-log regression models were used to evaluate the associations between case number and continuous outcomes (OT, WIT, and FVL). Multivariable logistic regression models were used to evaluate the association of case number with dichotomous outcomes (trifecta, postoperative complications, RR).

RESULTS

Among the 406 eligible patients included in the study, 252 (62.1%) were male, median age was 63 years (range, 22-84), and median body mass index was 29 kg/m² (interquartile range 26-33). Surgeon experience was associated with shorter OT (-2.5% per 50% increase in case number; 95% confidence interval; P <.001) and plateaus around 77 cases performed. There was slight improvement with trifecta (odds ratio [per 50% increase in cases] = 1.08; 95% confidence interval) and the plateau was also at 77 cases, however, this was not statistically significant (P = .086). We did not find statistically significant associations of surgeon experience with FVL (P = .77), postoperative complications (P = .74), WIT (P = .73), or 30-day RR (P = .33).

CONCLUSION

There does not appear to be a relationship between surgical experience and grade 3 or higher postoperative complications, 30-day RR, WIT, or FVL. Trifecta outcomes and maximum OT performance appear to be optimized at approximately 77 cases.

Quality and Quantity in Kidney Cancer Surgery: The Role of Nonneoplastic Kidney and Kidney Volumetrics in Predicting Postoperative Renal Function

Objectives

To model renal function 2 years following radical nephrectomy with quantitative analyses using clinical, histopathologic, and renal composite cortical volumes (CCV).

Methods

This retrospective study involved an assessment of the nonneoplastic kidney tissue by three blinded nephropathologists using modified Banff 1997 criteria for renal allograft pathology. Volumetric image acquisition was obtained by three independent radiologists using preoperative imaging. A 2-year estimated glomerular filtration (eGFR) calculator was created.

Results

Among the 126 patients, median age was 60 years; median CCV, 398.1 cm3; preoperative eGFR, 77 mL/min/1.73 m2; and 2-year postoperative eGFR, 54 mL/min/1.73 m2. Of the subjects, 64% had hypertension, 26% diabetes, and 37% were smokers. Increasing age, glomerulopathy/sclerosis, tubulointerstitial scarring, and arteriosclerosis were statistically significantly and adversely associated with eGFR. Conversely, increasing CCV was associated with a higher eGFR.

Conclusions

Quantitative analysis of the nephrectomized kidney in conjunction with patient age can accurately predict renal function at 2 years.

Frontiers in robot-assisted retroperitoneal oncological surgery

Robot assistance has been rapidly adopted by urological surgeons and has become particularly popular for oncological procedures involving the retroperitoneal space. The wide dissemination of robot assistance probably reflects the limited amount of operating space available within the retroperitoneum and the advantages provided by robot-assisted approaches, including 3D imaging, wristed instrumentation and the shorter learning curve compared with that associated with the equivalent laparoscopic techniques. Surgical procedures that have traditionally been performed using an open or laparoscopic approach, such as partial nephrectomy, radical nephrectomy, retroperitoneal lymph node dissection, nephroureterectomy and adrenalectomy, are now often being performed using robot assistance. The frontiers of robot-assisted retroperitoneal oncological surgery are constantly expanding, with an emphasis on maintaining oncological and functional outcomes, while minimizing the level of surgical invasiveness.

Renal cell carcinoma: new insights and challenges for a clinician scientist

There is a growing recognition of the complex interplay between renal cell cancer (RCC), kidney function, mechanical reduction of nephron mass, and systemic agents targeting the cancer. Earlier detection of RCC and rising life expectancy of cancer survivors places a greater emphasis on preservation of renal function after cancer resection and during systemic therapy. Unique adverse effects associated with RCC drugs not only help reveal cancer pathophysiology but also expand our knowledge of normal cell signaling and metabolism. In this review, we outline our current understanding of RCC biology and treatment, their bidirectional relationship with kidney function, and unmet research needs in this field.

Decline in renal function after partial nephrectomy: etiology and prevention

PURPOSE

Partial nephrectomy is the reference standard for the management of small renal tumors and is commonly used for localized kidney cancer. A primary goal of partial nephrectomy is to preserve as much renal function as possible. New baseline glomerular filtration rate after partial nephrectomy can have prognostic significance with respect to long-term outcomes. Recent studies provide an increased understanding of the factors that determine functional outcomes after partial nephrectomy as well as preventive measures to minimize functional decline. We review these advances, highlight ongoing controversies and stimulate further research.

MATERIALS AND METHODS

A comprehensive literature review consistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria was performed from January 2006 to April 2014 using PubMed®, Cochrane and Ovid Medline. Key words included partial nephrectomy, renal function, warm ischemia, hypothermia, nephron mass, parenchymal volume, surgical approaches to partial nephrectomy, preoperative and intraoperative imaging, enucleation, hemostatic agents and energy based resection. Relevant reviews were also examined as well as their cited references. An additional Google Scholar search was conducted to broaden the scope of the review. Only English language articles were included in the analysis. The primary outcomes of interest were the new baseline level of function after early postoperative recovery, percent decline in function, potential etiologies and preventive measures.

RESULTS

Decline in function after partial nephrectomy averages approximately 20% in the operated kidney, and can be due to incomplete recovery from the ischemic insult or loss of nephron mass related to parenchymal excision or collateral damage during reconstruction. Compensatory hypertrophy in the contralateral kidney after partial nephrectomy in adults is marginal and decline in global renal function for patients with 2 kidneys averages about 10%, although there is some variance based on tumor size and location. Irreversible ischemic injury can be minimized by pharmacological intervention or surgical approaches such as hypothermia, limited warm ischemia, or zero or segmental ischemia. Excessive loss of nephron mass can be minimized by improved preoperative or intraoperative imaging, use of a bloodless field, enucleation and vascular microdissection. Hemostatic agents or energy based resection that minimizes the need for parenchymal and capsular suturing can also optimize preservation of the vascularized nephron mass.

CONCLUSIONS

Our understanding of the decline in renal function after partial nephrectomy has advanced considerably, including better appreciation of its magnitude and impact in various settings, possible etiologies and potential preventive measures. Many controversies persist and this remains an important area of investigation.

Increasing volume of non-neoplastic parenchyma in partial nephrectomy specimens is associated with chronic kidney disease upstaging

INTRODUCTION

We examined the effect of non-neoplastic parenchymal volumes (NNPVs) in partial nephrectomy (PN) surgical specimens on long-term postoperative renal function. PN for renal cortical neoplasms has demonstrated superior long-term renal function outcomes compared with radical nephrectomy. Minimizing the distance between the surgical margin and tumor will reduce the NNPV removed. The role of NNPV on postoperative outcomes has been preliminarily investigated, with varying results. Thus, we sought to determine the association between the NNPV removed and postoperative chronic kidney disease (CKD) staging.

MATERIALS AND METHODS

Our institutional database was queried for patients who had undergone PN from 1990 to 2012. The demographic and pathologic data were collected. The ellipsoid formula was used to calculate the surgical specimen and tumor volumes, which were then subtracted from each other to determine the NNPV. The estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease formula. Binary logistic regression analysis was used to determine the predictors of postoperative CKD upstaging according to the eGFR.

RESULTS

A total of 584 patients meeting the inclusion criteria had undergone PN. On binary logistic regression analysis, controlling for age, tumor volume, surgical modality, and preoperative CKD stage, an increasing NNPV in the surgical specimen was independently associated with postoperative CKD upstaging (odds ratio, 1.004; P = .007).

CONCLUSION

An increasing NNPV removed during PN correlated with CKD upstaging using the eGFR; therefore, additional emphasis should be placed on healthy parenchymal preservation, with long-term follow-up to ensure adequate oncologic outcomes.