The role of warm ischemia time on functional outcomes after robotic partial nephrectomy: a radionuclide renal scan study from the clock randomized trial

Abstract

Purpose To evaluate the relationship between warm ischemia time (WIT) duration and renal function after robot-assisted partial nephrectomy (RAPN). Methods The CLOCK trial is a phase 3 randomized controlled trial comparing on- vs off-clamp RAPN. All patients underwent pre- and postoperative renal scintigraphy. Six-month absolute variation of eGFR (AV-GFR), rate of relative variation in eGFR over 25% (RV-GFR > 25), absolute variation of split renal function (SRF) at scintigraphy (AV-SRF). The relationships WIT/outcomes were assessed by correlation graphs and then modeled by uni- and multivariable regression. Results 324 patients were included (206 on-clamp, 118 off-clamp RAPN). Correlation graphs showed a threshold on WIT equal to 10 min. The differences in outcome measures between cases with WIT < vs ≥ 10 min were: AV-GFR − 3.7 vs − 7.5 ml/min (p < 0.001); AV-SRF − 1% vs − 3.6% (p < 0.001); RV-GFR > 25 9.3% vs 17.8% (p = 0.008). Multivariable models found that AV-GFR was related to WIT ≥ 10 min (regression coefficient [RC] − 0.52, p = 0.019), age (RC − 0.35, p = 0.001) and baseline eGFR (RC − 0.30, p < 0.001); RV-GFR > 25 to WIT ≥ 10 min (odds ratio [OR] 1.11, p = 0.007) and acute kidney injury defined as > 50% increase in serum creatinine (OR 19.7, p = 0.009); AV-SRF to WIT ≥ 10 min (RC − 0.30, p = 0.018), baseline SRF (RC − 0.76, p < 0.001) and RENAL score (RC − 0.60. p = 0.028). The main limitation was that the CLOCK trial was designed on a different endpoint and therefore the present analysis could be underpowered. Conclusions Up to 10 min WIT had no consequences on functional outcomes. Above the 10-min threshold, a statistically significant, but clinically negligible impact was found.

Short- and Long-Term Renal Function After Partial Nephrectomy: Comparison of Solitary and Multifocal Renal Masses

“…22 The 2023 CLOCK trial used radionuclide renal scintigraphy to demonstrate that WIT below 10 minutes had no impact, and each minute spent over 10 minutes had only clinically negligible impacts, on GFR 6 months after on- vs off-clamp PN. 23 Regardless, our study shows that in a high-volume center, surgeons can limit WIT within an acceptable range for complex multifocal resections.…”

Can the Abdominal Aortic Atherosclerotic Plaque Index Predict Functional Outcomes after Robot-Assisted Partial Nephrectomy?

“…Data from the CLOCK randomized trial demonstrated both no impact of ischemia time on renal function in the context of two kidneys and normal function [10], and the negligible clinical effects of ischemia above the threshold of 10 min [23], in those patients undergoing RAPN. However, this was a multicenter randomized trial involving very experienced surgeons, and the results might be different in a common clinical scenario.…”

How many cases are required to achieving early proficiency in purely off-clamp robot-assisted partial nephrectomy?

“…Some experts recognized 25 min of WIT as the threshold for acute kidney injury (AKI) ( 22 ). It has been suggested that limited WIT (≤10 min) had no consequences on renal function ( 23 ). Other studies have shown that limited or zero ischemia time might have not a significant impact on renal function ( 24 – 26 ).…”