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Sources of Funding: none

Introduction

Renal function immediately following partial nephrectomy (PN) may depend on the modifiable factors of warm ischemia time (WIT) and excisional volume loss (EVL). Our aim was to examine how their dynamic interaction influenced predicted rates of post-PN acute kidney injury (AKI) across a range of tumor complexities.

Methods

We retrospectively reviewed 1,162 patients in our single-institution robotic PN database and captured sociodemographic, clinical, and radiologic characteristics. EVL was calculated as the difference between specimen and tumor volume based on pathological assessment. AKI was defined as a change in preoperative GFR >25% within 72 hours of surgery, or stage 1 of the RIFLE criteria. Multivariate logistic regressions, followed by marginal effects, were run to examine the interaction effect of ischemia type, volume loss, and R.E.N.A.L. score on rates of AKI.

Results

There was a significant interaction effect of WIT and log EVL on predicted rates of AKI (p<0.001). Each doubling of EVL caused a 4.03% and 8.46% increased probability of AKI, respectively, for WIT of <25 minutes and >25 minutes. At excisional volume losses >5.5cm³, prolonged WIT had statistically greater odds of causing AKI (Figure 1). These predicted effects on AKI were amplified for increasing R.E.N.A.L. scores (p<0.001).

Conclusions

Rates of AKI after PN are highly correlated to the dynamic compounding influence of WIT and EVL. As excisional imprecision increases, the added insult from prolonged warm ischemia time become more profound, a &[Prime]two hit&[Prime] model for parenchymal insult. This effect was further modulated by tumor complexity, with increasing scores predicting an increased effect. Together, this suggests that limiting WIT and minimizing volume loss, especially in complex tumors, can mitigate rates of postoperative AKI. Given the associated morbidity and mortality of AKI, further efforts to carefully control these modifiable factors are of particular interest.

Funding

none