Elvis R. Caraballo

Impact of Comorbidities on Functional Recovery from Partial Nephrectomy

Purpose: Parenchymal mass preservation, and ischemia type and/or duration can influence functional recovery after partial nephrectomy. Some groups have hypothesized that relevant comorbidities may also impact nephron stability and functional recovery but this has not been adequately investigated. Materials and Methods: At our center 405 patients treated with partial nephrectomy from 2007 to 2015 had the necessary data to determine the function and parenchymal mass preserved in the ipsilateral kidney. Comorbidities potentially associated with renal functional status were reviewed, including various degrees of hypertension, diabetes, cardiovascular disease, obesity, smoking status and related medications. Multivariable linear regression was done to assess factors associated with functional recovery, defined as the percent of preserved ipsilateral glomerular filtration rate. Results: Median tumor size was 3.5 cm and the median R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines and tumor touching main renal artery or vein) score was 8. Warm and cold ischemia were done in 264 (65%) and 141 patients for a median duration of 21 and 27 minutes, respectively. The median preserved ipsilateral glomerular filtration rate was 79%. Patient age, comorbidity index, hypertension and proteinuria were each associated with the preoperative glomerular filtration rate (all p <0.01). On univariable and multivariable analyses the preserved parenchymal mass, and ischemia type and duration were significantly associated with functional recovery (all p <0.001). On univariable analysis of comorbidities only hypertension was significantly associated with functional recovery. However, on multivariable analysis none of the analyzed comorbidities were associated with functional recovery. Conclusions: Recovery of function after partial nephrectomy depends primarily on parenchymal mass preservation and ischemia characteristics. Comorbidities failed to be associated with functional outcomes. Comorbidities can impact function, leading to surgery, and may influence long‐term functional stability. However, our data suggest that they do not influence short‐term recovery after partial nephrectomy.

Tumor Contact Surface Area As a Predictor of Functional Outcomes After Standard Partial Nephrectomy: Utility and Limitations

OBJECTIVE To evaluate contact surface area (CSA) between the tumor and parenchyma as a predictor of ipsilateral parenchyma and function preserved after partial nephrectomy (PN). Previous studies suggested that CSA is a strong predictor of functional outcomes but the limitations of CSA have not been adequately explored. PATIENTS AND METHODS Four hundred nineteen patients managed with standard PN for solitary tumor with necessary studies to evaluate and analyze ipsilateral preoperative or postoperative parenchymal mass and function. Parenchymal mass and CSA were measured using contrast-enhanced computed tomography <2 months prior and 3-12months after PN. CSA was calculated: 2πrd, where r = radius and d = intraparenchymal depth. Pearson-correlation evaluated relationships between CSA and ipsilateral parenchymal mass or function preserved. Multivariable regression assessed predictors of function preserved. Conceptually, the CSA paradigm should function better for exophytic tumors than endophytic ones. RESULTS Median tumor size was 3.5 cm and R.E.N.A.L. was 8. Median global and ipsilateral glomerular filtration rate preserved were 89% and 79%, respectively. Median ipsilateral parenchymal mass preserved was 85% and significantly higher for exophytic masses (P = .001). Median CSA was 22.8 cm2 and significantly less for exophytic masses (P = .02). CSA associated with both ipsilateral function and mass preserved (both P < .05), but the correlations were only modest (r = 0.25 and 0.36, respectively). On multivariable analysis, CSA associated with function preserved for exophytic masses (P = .01), but not for endophytic ones (P = .27). CONCLUSION CSA associates with functional outcomes after standard PN, although the strength of the correlations was modest, unlike previous studies, and CSA was not an independent predictor for endophytic tumors. Further study will be required to evaluate the utility of CSA in various clinical settings.

Can We Predict Functional Outcomes after Partial Nephrectomy

Purpose: The percent of preserved parenchymal mass is the primary determinant of functional outcomes after partial nephrectomy. Accurate methods to predict the percent of preserved parenchymal mass based on preoperative imaging could facilitate patient counseling. Materials and Methods: We evaluated the records of 428 patients who had undergone partial nephrectomy and the studies necessary to assess preserved ipsilateral parenchymal mass and function. Preoperative and postoperative ipsilateral parenchymal volumes were measured from contrast enhanced computerized tomography less than 2 months before and 3 to 12 months after partial nephrectomy and the actual percent of preserved parenchymal mass was determined. The ipsilateral percent of preserved parenchymal mass and the final global glomerular filtration rate were estimated based on preoperative imaging using subjective estimation, quantitative estimation, or estimation derived from the contact surface area or the R.E.N.A.L. (radius, exophytic/endophytic, nearness of tumor to collecting system or sinus, anterior/posterior and location relative to polar lines) score. Results: Median tumor diameter was 3.5 cm, median contact surface area was 24 cm2 and the median R.E.N.A.L. score was 8. The median actual ipsilateral percent of preserved parenchymal mass was 84% and the preserved percent of the global glomerular filtration rate was 89%. The median estimated ipsilateral percent of preserved parenchymal mass was 85%, 87%, 88% and 83% based on subjective estimation, quantitative estimation, contact surface area and the R.E.N.A.L. score, respectively. Correlations between the actual and the estimated percent of preserved parenchymal mass were relatively weak in all instances (all r ⩽0.46). Prediction of the final global glomerular filtration rate was strong for all 4 methods (all r = 0.91). However, a similarly strong correlation was obtained when presuming that 89% of the preoperative global glomerular filtration rate would be saved in each case (r = 0.91). On multivariable analyses a solitary kidney, the preoperative glomerular filtration rate and various estimates of the percent of preserved parenchymal mass were significantly associated with the final global glomerular filtration rate. However, the preoperative glomerular filtration rate proved to be the strongest predictor. It had more than a tenfold impact compared to the estimated percent of preserved parenchymal mass or a solitary kidney. Conclusions: Currently available methods to estimate the percent of preserved parenchymal mass have important limitations. The final global glomerular filtration rate, which is the most important functional outcome, could be predicted fairly accurately by all tested methods. However, none of them were better than simply presuming that 89% of function would be saved due to strong anchoring to the preoperative glomerular filtration rate.

MP49-10 ISCHEMIA AND FUNCTIONAL RECOVERY FROM PARTIAL NEPHRECTOMY: REFINED PERSPECTIVES

INTRODUCTION AND OBJECTIVES: Partial nephrectomy (PN) is the standard treatment for localized renal cancer due to better preservation of renal function. Previous studies suggested that parenchymal mass preservation is a key determinant of functional outcomes, while ischemia plays a secondary role. Analyses that focus specifically on recovery of the kidney exposed to ischemia appear to be most informative, yet have only included limited numbers of patients. Our objective is to provide a more refined evaluation of the impact of ischemia type and duration using more robust numbers of patients analyzed in this manner. METHODS: A total of 401 patients with PN at our center (20072015) had necessary data for analysis, including serum creatininebased estimated glomerular filtration rate (GFR) and contrast-enhanced cross-sectional imaging studies <2 months prior and 3-12 months after PN. Patients with 2 kidneys were also required to have split renal function from nuclear renal scans within the same timeframes. Recovery from ischemia was defined as percent function preserved in the ipsilateral kidney normalized by percent parenchymal mass preserved. Pearson correlation evaluated the relationships between functional recovery and parenchymal mass preserved or ischemia time. Multivariable linear regression assessed predictors for recovery. RESULTS: Median tumor size was 3.5 cm and median R.E.N.A.L. was 8. Cold/warm ischemia were utilized in 151/250 patients, and median ischemia times were 27/21 minutes, respectively. Parenchymal mass preserved correlated strongly with function preserved (r1⁄40.63, p<0.001). Median recovery from ischemia, which normalizes for parenchymal mass preservation, was significantly higher for hypothermia than warm ischemia (99% vs. 92%, p<0.001) and remained consistently strong even with longer duration of cold ischemia. Multivariable analysis demonstrated that ischemia type and duration associated significantly with recovery from ischemia (p<0.05). However, each additional 10 minutes of warm ischemia associated with only 2.5% decline in recovery from ischemia. CONCLUSIONS: Parenchymal mass preservation is the primary factor affecting functional outcomes after clamped PN. Beyond this, functional recovery is most reliable with hypothermia. Longer intervals of warm ischemia associate with reduced recovery; however, incremental changes are modest and of debatable clinical significance, particularly in patients with a normal contralateral kidney.