Every decade counts: a narrative review of functional recovery after partial nephrectomy.

OBJECTIVE: To provide a narrative review of the major advances regarding ischaemia and functional recovery after partial nephrectomy (PN), along with the ongoing controversies. METHODS: Key articles reflecting major advances regarding ischaemia and functional recovery after PN were identified. Special emphasis was placed on contributions that changed perspectives about surgical management. Priority was also placed on randomized trials of off-clamp vs on-clamp cohorts. RESULTS: A decade ago, 'Every minute counts' was published, showing strong correlations between duration of ischaemia and development of acute kidney injury (AKI) and chronic kidney disease after clamped PN. This reinforced perspectives that ischaemia was the main modifiable factor that could be addressed to improve functional outcomes and helped spur efforts towards reduced or zero ischaemia PN. These approaches were associated with strong functional recovery and some peri-operative risk, although they were generally safe in experienced hands. Further research demonstrated that, when parenchymal volume changes were incorporated into the analyses, ischaemia lost statistical significance, and percent parenchymal volume saved proved to be the main determinant. Cold ischaemia was confirmed to be highly protective, and limited warm ischaemia also proved to be safe. The reconstructive phase of PN, with avoidance of parenchymal devascularization, appears to be most important for functional outcomes. Randomized trials of on-clamp vs off-clamp PN have shown minimal impact of ischaemia on functional recovery. CONCLUSIONS: The past decade has witnessed great progress regarding functional recovery after PN, with many lessons learned. However, there are still unanswered questions, including: What is the threshold of warm ischaemia at which irreversible ischaemic injury begins to develop? Are some cohorts at increased risk for AKI or irreversible ischaemic injury? and Which patients should be prioritized for zero-ischaemia PN?

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.

Lung density in the trajectory path is a strong indicator of patients sustaining a pneumothorax during CT-guided lung biopsy.

INTRODUCTION: The purpose is to evaluate the prognostic significance of lung parenchymal density during percutaneous coaxial cutting needle lung biopsy (PNLB). MATERIALS AND METHODS: Retrospective analysis of 179 consecutive patients (106 males, 73 females; mean age 59.16 ± 16.34 years) undergoing PNLB was included. Mean lobar parenchymal lung density, mean densities anterior to the lesion and posterior to the chest wall in the needle trajectory path were measured in HU. Lesion location and needle trajectory were also measured. Fisher's exact test and Chi-square test were conducted to analyze the categorical variables. ANOVA test was done to examine continuous and normally distributed variables. Statistical significance was considered when p < 0.05. RESULTS: Mean lobar parenchymal lung density (p < 0.05) and mean parenchymal lung density relative to the needle trajectory path were below -800 HU in patients who sustained a pneumothorax. Increase in the number of pleural passes was significantly associated with the risk of patients having pneumothorax (p < 0.05). The mean distance from the skin to the lesion and needle trajectory angle were not statistically different among patients with and without pneumothorax (p > 0.05). CONCLUSION: Lobar parenchymal density and lung parenchymal density anterior to the lesion and posterior to the chest wall in the needle trajectory path could be used as predicting parameters in patients undergoing PNLB who sustained a pneumothorax. These findings can help interventional radiologist further assess risk of pneumothorax when preforming such procedure.

Acute Kidney Injury Adjusted for Parenchymal Mass Reduction and Long-Term Renal Function after Partial Nephrectomy.

We sought to evaluate the association of postoperative acute kidney injury (AKI) adjusted for parenchymal mass reduction with long-term renal function in patients undergoing partial nephrectomy. A total of 629 patients undergoing partial nephrectomy were reviewed. Postoperative AKI was defined by the Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria, by using either the unadjusted or adjusted baseline serum creatinine level, accounting for renal parenchymal mass reduction. Estimated glomerular filtration rates (eGFRs) were followed up to 61 months (median 28 months) after surgery. The primary outcome was the functional change ratio (FCR) of eGFR calculated by the ratio of the most recent follow-up value, at least 24 months after surgery, to eGFR at 3-12 months after surgery. Multivariable linear regression analysis was performed to evaluate whether unadjusted or adjusted AKI was an independent predictor of FCR. As a sensitivity analysis, functional recovery at 3-12 months after surgery compared to the preoperative baseline was analyzed. Median parenchymal mass reduction was 11%. Unadjusted AKI occurred in 16.5% (104/625) and adjusted AKI occurred in 8.6% (54/629). AKI using adjusted baseline creatinine was significantly associated with a long-term FCR (ß = -0.129 ± 0.026, p < 0.001), while unadjusted AKI was not. Adjusted AKI was also a significant predictor of functional recovery (ß = -0.243 ± 0.106, p = 0.023), while unadjusted AKI was not. AKI adjusted for the parenchymal mass reduction was significantly associated with a long-term functional decline after partial nephrectomy. A creatinine increase due to remaining parenchymal ischemic injury may be important in order to predict long-term renal functional outcomes after partial nephrectomy.

Vascularized Parenchymal Mass Preserved with Partial Nephrectomy: Functional Impact and Predictive Factors.

BACKGROUND: Percentage parenchymal mass preserved (PPMP) is a key determinant of functional outcomes after partial nephrectomy (PN); however, predictors of PPMP have not been defined. OBJECTIVE: To provide a comprehensive analysis of the functional impact of and potential predictive factors for PPMP. DESIGN, SETTING, AND PARTICIPANTS: We analyzed data for 464 patients managed with PN at our center with necessary studies to determine vascularized parenchymal mass and function preserved within the operated kidney. PPMP was measured from computed tomography scans <2 mo before and 3-12 mo after PN. INTERVENTION: PN. OUTCOME MEASUREMENTS/STATISTICAL ANALYSIS: Recovery from ischemia was defined as percentage ipsilateral glomerular filtration rate (GFR) preserved normalized by PPMP. We used Pearson correlation to evaluate the relationships between GFR preserved and PPMP. Multivariable logistic regression was used to assess predictors of PPMP. RESULT AND LIMITATIONS: Ninety-six patients (21%) had a solitary kidney. The median tumor size and RENAL score were 3.5cm and 8, respectively. Cold/warm ischemia were utilized in 183/281 patients for which the median ischemia time were 28/20min. The median preoperative and postoperative vascularized parenchymal mass in the operated kidney were 194 and 157cm3, respectively, resulting in median PPMP of 84%. GFR preservation correlated strongly with PPMP (r=0.64; p<0.001). Recovery from ischemia was suboptimal (<80%) in 71 patients (15%), while suboptimal PPMP (<80%) was a more common adverse event, occurring in 160 patients (34%; p<0.001). Multivariable analysis demonstrated that greater tumor size and complexity were associated with lower PPMP (p≤0.04), while solitary kidney and hypothermia were associated with higher PPMP (p<0.001). Longer ischemia time was also associated with lower PPMP (p=0.003), probably reflecting the complexity of the surgery. Limitations include the retrospective design. CONCLUSION: PPMP correlates strongly with functional outcomes after PN, and lower PPMP is the most common and important source of functional decline after PN. Larger tumors, greater tumor complexity, and prolonged ischemia time were associated with lower PPMP, while PPMP tended to be greater for solitary kidneys, confirming that PPMP is a modifiable factor. PATIENT SUMMARY: Kidney function after partial nephrectomy primarily depends on the amount of vascularized kidney preserved by the procedure. Lower recovery of function is seen when operating on larger tumors in unfavorable locations, but preservation of the parenchymal mass can be improved when truly necessary, such as when operating on a tumor in a solitary kidney.

Ischemia and Functional Recovery from Partial Nephrectomy: Refined Perspectives.

BACKGROUND: Nephron mass preservation is a key determinant of functional outcomes after partial nephrectomy (PN), while ischemia plays a secondary role. Analyses focused specifically on recovery of the operated kidney appear to be most informative, yet have only included limited numbers of patients. OBJECTIVE: To evaluate the relative impact of parenchymal preservation and ischemia on functional recovery after PN using a more robust cohort allowing for more refined perspectives about ischemia. DESIGN, SETTING, AND PARTICIPANTS: A total of 401 patients managed with PN with necessary studies were analyzed for function and nephron mass preserved specifically within the kidney exposed to ischemia. INTERVENTION: PN. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The nephron mass preserved was measured from computed tomography scans <2 mo before and 3-12 mo after PN. Patients with two kidneys were required to have nuclear renal scans within the same timeframes. Recovery from ischemia was defined as the percent function preserved normalized by the percent nephron mass preserved. Pearson correlation was used to evaluate relationships between functional recovery and nephron mass preservation or ischemia time. Multivariable linear regression assessed predictors for recovery from ischemia. RESULTS AND LIMITATIONS: The median tumor size was 3.5cm and the median RENAL score was 8. Cold and warm ischemia were utilized in 151 and 250 patients, and the median ischemia time was 27 and 21min, respectively. The function preserved was strongly correlated with nephron mass preserved(r=0.63; p<0.001). Median recovery from ischemia was significantly higher for hypothermia (99% vs 92%; p<0.001) and remained consistently strong even with longer duration. Multivariable analysis demonstrated that recovery from ischemia, which normalizes for nephron mass preservation, was significantly associated with ischemia type and duration (both p<0.05). However, each additional 10min of warm ischemia was associated with only a 2.5% decline in recovery from ischemia. Limitations include the retrospective design. CONCLUSIONS: Our data suggest that functional recovery from clamped PN is most reliable with hypothermia. Longer intervals of warm ischemia are associates with reduced recovery; however, incremental changes are modest and may not be clinically significant in patients with a normal contralateral kidney. PATIENT SUMMARY: Functional recovery after clamped partial nephrectomy is primarily dependent on preservation of nephron mass. Recovery is most reliable when hypothermia is applied. Longer intervals of warm ischemia are associated with reduced recovery; however, the incremental changes are modest.

Functional Comparison of Renal Tumor Enucleation Versus Standard Partial Nephrectomy.

BACKGROUND: Tumor enucleation (TE) optimizes parenchymal preservation and could yield better function than standard partial nephrectomy (SPN), although data on this are conflicting. OBJECTIVE: To compare functional outcomes for TE and SPN strategies. DESIGN, SETTING, AND PARTICIPANTS: Patients managed with partial nephrectomy (PN) with necessary data for analysis of preservation of ipsilateral parenchymal mass (IPM) and global glomerular filtration rate (GFR) from two centers were included. All studies were required <2 mo before and 3-12 mo after surgery. Patients with a solitary kidney or multifocal tumors were excluded. INTERVENTION: Partial nephrectomy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Vascularized IPM was estimated from contrast-enhanced CT scans preoperatively and postoperatively. Serum creatinine-based estimates of global GFR were also obtained in the same timeframes. Univariable and multivariable linear regression evaluated factors associated with new-baseline global GFR. RESULTS/LIMITATIONS: Analysis included 71 TE and 373 SPN cases. The median preoperative global GFR was comparable for TE and SPN (75 vs 78ml/min/1.73m2; p=0.6). The median tumor size was 3.0cm for TE and 3.3cm for SPN (p=0.03). The median RENAL score was 7 in both cohorts. For TE, warm ischemia and zero ischemia were used in 51% and 49% of cases, respectively. For SPN, warm ischemia and cold ischemia were used in 72% and 28% of patients, respectively. Capsular closure was performed in 46% of TE and 100% of SPN cases (p<0.001). Positive margins were found in 8.5% of TE and 4.8% of SPN patients (p=0.2). The median vascularized IPM preserved was 95% (interquartile range [IQR] 91-100%) for TE and 84% (IQR 76-92%) for SPN (p<0.001). The median global GFR preserved was 101%(IQR 93-111%) and 89% (IQR 81-96%) for TE and SPN, respectively (p<0.001). On multivariable analysis, resection strategy, preoperative GFR, and vascularized IPM preserved were all significantly associated (p<0.001) with new-baseline global GFR. Limitations include the retrospective design and the lack of resection outcome data. CONCLUSIONS: Our analysis suggests that TE has potential for maximum IPM preservation compared to SPN and may provide optimized functional recovery. Further investigation will be required to evaluate the clinical significance of these findings. PATIENT SUMMARY: Tumor enucleation for kidney cancer involves dissection along the tumor capsule and optimally preserves normal kidney tissue, which may lead to better functional recovery. The importance of this approach in various clinical settings will require further investigation.

Acute Ipsilateral Renal Dysfunction after Partial Nephrectomy in Patients with a Contralateral Kidney: Spectrum Score to Unmask Ischemic Injury.

BACKGROUND: Acute ischemic injury in the operated kidney after partial nephrectomy (PN) is often masked by a functional contralateral kidney; however, there is no practical method to assess this and its prognostic significance has not been defined. OBJECTIVE: We propose a spectrum score to reflect the degree of ischemic insult in the ipsilateral kidney and study its relationship to subsequent functional recovery. DESIGN, SETTING, AND PARTICIPANTS: From 2007 to 2014, 243 patients with a functional contralateral kidney underwent PN with necessary studies for detailed analysis of function and parenchymal mass before and after surgery in the ipsilateral kidney. Based on split function and percent parenchymal mass preserved in the ipsilateral kidney, we determined: serum creatinine (SCr)ideal-peak: expected peak SCr presuming no ischemic injury; and SCrworstcase-peak: expected peak SCr presuming temporary complete nonfunction of the ipsilateral kidney. The acute ipsilateral renal dysfunction spectrum score was defined: (observed peak SCr - SCrideal-peak)/(SCrworstcase-peak - SCrideal-peak). Subsequent functional recovery was defined: (percent function preserved)/(percent mass saved). INTERVENTION: PN. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Factors associated with spectrum score and relationship between spectrum score and subsequent functional recovery were evaluated by linear regression. RESULTS AND LIMITATIONS: Median duration of warm ischemia (n=152) was 21min (interquartile range [IQR] = 15-27) and hypothermia (n=91) 26min (IQR=23-30). Median parenchymal mass preservation was 83% (IQR=74-91%). Warm ischemia and longer ischemia duration associated with higher spectrum score (both p<0.05). Increased spectrum score (<25%, 25-50%, 50-75%, and >75% quartiles) had decreased functional recovery (98%, 94%, 90%, and 89%, respectively, p<0.001). However, this trend was not observed in the hypothermia cohort. On multivariable analysis spectrum score and ischemia type significantly associated with functional recovery (both p<0.01), while age and comorbidities failed to associate (p=0.3-0.7). CONCLUSIONS: Acute ipsilateral renal dysfunction spectrum score unmasks the degree of ischemic insult in the operated kidney after PN and associates with functional recovery. While increased spectrum score associates with suboptimal recovery, even patients with a high spectrum score reached 89-90% recovery. PATIENT SUMMARY: Acute functional decline after partial nephrectomy is difficult to evaluate in patients with two kidneys, but a proposed spectrum score can be used to evaluate this. Increased spectrum score reflects increased ischemia and may impact the functional recovery of the kidney.

Acute Kidney Injury after Partial Nephrectomy: Role of Parenchymal Mass Reduction and Ischemia and Impact on Subsequent Functional Recovery.

BACKGROUND: Acute increase of serum creatinine (SCr) after partial nephrectomy (PN) is primarily due to parenchymal mass reduction or ischemia; however, only ischemia can impact subsequent functional recovery. OBJECTIVE: We evaluate etiologies of acute kidney injury (AKI) after PN and their prognostic significance. DESIGN, SETTING, AND PARTICIPANTS: From 2007-2014, 83 solitary kidneys managed with PN had necessary studies for detailed analysis of function and parenchymal mass before/after surgery. AKI was classified by Risk/Injury/Failure/Loss/Endstage classification and defined by either standard criteria (comparison to preoperative SCr) or proposed criteria (comparison to projected postoperative SCr based on parenchymal mass reduction). Subsequent recovery was defined as percent function preserved/percent mass saved. INTERVENTION: PN. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Predictive factors for AKI were evaluated by logistic regression. Relationship between AKI grade and subsequent functional recovery was assessed by linear regression. RESULTS AND LIMITATIONS: Median duration warm ischemia (n=39) was 20 min and hypothermia (n=44) was 29 min. Median parenchymal mass reduction was 11%. AKI occurred in 45 patients based on standard criteria and 38 based on proposed criteria, and reflected injury/failure (grade = 2/3) in 23 and 16 patients, respectively. On multivariable analysis, only ischemia time associated with AKI occurrence (p=0.016). Based on the proposed criteria, median recovery from ischemia was 99% in patients without AKI and 95%/90%/88% for patients with grades 1/2/3 AKI, respectively. The coefficient for association between AKI grade based on proposed criteria and subsequent functional recovery was -4.168 (p=0.018). Main limitation is limited patient cohort. CONCLUSIONS: Parenchymal mass reduction and ischemia both contribute to acute changes in SCr after PN. Classification of AKI by proposed criteria significantly associates with subsequent functional recovery. However, more robust numbers will be needed to further assess the merits of the proposed criteria. While AKI is associated with suboptimal recovery, even patients with grade 2/3 AKI reached 88-90% of recovery expected. PATIENT SUMMARY: Acute decline in function after partial nephrectomy associates with more prolonged ischemia time, and appears to impact subsequent functional recovery. However, most kidneys eventually recover strongly, even if their function is sluggish in the first few days after surgery.