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Page 10 of 13 Parra et al. Mini-invasive Surg 2024;8:16 https://dx.doi.org/10.20517/2574-1225.2024.01

histological findings between ischemia time < 25 and ≥ 25 min and between warm ischemia and cold
ischemia showed no significant difference in CKD scores between samples. However, the existence of
comorbidities (hypertension, diabetes mellitus, or pre-existing CKD) was associated with significant
deterioration of the histologic CKD score between the PN and RN samples, which would imply that the
patient’s comorbidities contribute more than the type or duration of ischemia to the objectified chronic
changes in the kidney.

In the CLOCK trial [16,27] , an average variance of 14 min in WIT did not significantly affect renal function at 6
[28]
months after surgery. Subsequently, in the CLOCK II trial , no differences were found neither in the
perioperative or early functional outcomes between on-clamp and off-clamp LPN.

In order to achieve functional results, to date, the literature has focused on defining a new baseline GFR
three and 6 months after surgery. Most studies have been dedicated to these time periods because they
correlate with long-term overall survival, mainly for patients with prior renal failure. More recent data,
however, has defined the function of ischemia in relation to the risk of AKI. AKI is frequently seen after PN
in patients with a solitary kidney and, in the series by Zhang et al., while AKI was observed in 45 out of 83
solitary kidneys (54%), only 38 patients (46%) were categorized as having AKI, when parenchymal mass
alterations were evaluated . Also, they summarize that most kidneys recuperate from AKI to 88%-99% of
[16]
[16]
the level predicted by nephron-mass preservation . In our study, we evaluated the GFR on the first
postoperative day, at 3 and 6 months after surgery, and found no relevant differences, with no statistically
significant differences in relation to the time of ischemia during surgery. This is possibly influenced by the
fact that 57.5% of the patients had previous CKD.

Predicting these results is challenging. Two models have recently been published in an attempt to predict
postoperative AKI and development of CKD stage 3b in patients undergoing PN or RN for kidney cancer.
The authors called them RENSAFE (RENalSAFEty) and conclude that male sex, American Society of
[29]
Anesthesiologists (ASA) score, hypertension, R.E.N.A.L. score, preoperative eGFR < 60 and RN are
predictors for AKI, while age, diabetes mellitus, preoperative eGFR < 60 and RN are predictors for CKD ≥
3b. These are easily implementable nomograms to decide with the patient the type of nephrectomy,
although the impact of AKI on post-surgical patients seems to be limited to less severe forms of CKD.

[30]
Another nomogram has recently been published , based on four risk categories of patients (low,
intermediate favorable, intermediate unfavorable and high-risk patients), to predict the risk of CKD-
upstaging at three years in patients undergoing a RAPN. The model included baseline GFR, solitary kidney
status, multiple lesions, R.E.N.A.L. score, clamping technique, and postoperative AKI. It showed that, based
on identified nomogram cut-offs (7% vs. 16% vs. 26%), there was a statistically significant increase in CKD-
upstaging rates between low vs. intermediate favorable vs. intermediate unfavorable vs. high-risk patients
(1.3% vs. 9.2% vs. 22% vs. 54.2%, respectively, P < 0.001).

Crocerossa et al. studied those variables influencing long-term renal function (one year after surgery) and
[31]
assessed their relative weight . They concluded with preoperative GFR, sex, ischemia technique, and
percentage loss (PPL) being the best predictors of GFR PPL at one year after minimally invasive PN.

With the use of robotics in the surgical treatment of RCC, the indication for RAPN has been expanded to
include the management of larger and higher complexity renal tumors . A systematic review in 2023
[32]
analyzed the outcomes of RAPN for completely endophytic, large tumors (cT2-T3), solitary kidneys,
recurrent tumors and hilar masses, and demonstrated favorable surgical outcomes with good preservation