Our aim was to evaluate the short- and long-term renal effects of warm ischemia in patients with a solitary kidney.
Design, setting, and participants
Using the Cleveland Clinic and Mayo Clinic databases, we identified 362 patients with a solitary kidney who underwent open (n = 319) or laparoscopic (n = 43) partial nephrectomy using warm ischemia with hilar clamping.
Measurements
Associations of warm ischemia time with renal function were evaluated using logistic or Cox regression models first as a continuous variable and then in 5-min increments.
Results and limitations
Median tumor size was 3.4 cm (range: 0.7–18.0 cm), and median ischemia time was 21 min (range: 4–55 min). Postoperative acute renal failure (ARF) occurred in 70 patients (19%) including 58 (16%) who had a glomerular filtration rate (GFR) <15 ml/min per 1.73 m2 within 30 d of surgery. Among the 226 patients with a preoperative GFR ≥ 30 ml/min per 1.73 m2 and followed ≥30 d, 38 (17%) developed new-onset stage IV chronic kidney disease during follow-up. As a continuous variable, longer warm ischemia time was associated with ARF (odds ratio: 1.05 for each 1-min increase; p < 0.001) and a GFR < 15 (odds ratio: 1.06; p < 0.001) in the postoperative period, and it was associated with new-onset stage IV chronic kidney disease (hazard ratio: 1.06; p < 0.001) during follow-up. Similar results were obtained adjusting for preoperative GFR, tumor size, and type of partial nephrectomy in a multivariable analysis. Evaluating warm ischemia in 5-min increments, a cut point of 25 min provided the best distinction between patients with and without all three of the previously mentioned end points. Limitations include the retrospective nature of the study.
Conclusions
Longer warm ischemia time is associated with short- and long-term renal consequences. These results suggest that every minute counts when the renal hilum is clamped.
Introduction
Interruption of renal blood flow via pedicle clamping is often necessary during partial nephrectomy, especially for hilar tumors or those with deep parenchymal invasion. Vascular clamping aids in hemostasis and allows precise surgical closure of the collecting system and reapproximation of the parenchymal defect. However, the most important factor governing the return of renal function remains the duration of ischemia time. The historically safe duration of warm ischemia time, where full recovery of renal function is expected, was commonly thought to be 30 min [1], [2]. More recently, we have observed that warm ischemia should be limited to 20 min whenever feasible [3], [4], [5], a notion that was recently supported by an international collaborative review of the literature [6].
Others have challenged the maximal safe duration of warm ischemia, suggesting that renal pedicle clamping for 90 min is safe in the porcine model [7], [8]. Furthermore, clinical observations have suggested that warm ischemia for 40–55 min is safe and effective [9], [10]. However, these studies included patients with normal contralateral kidneys, potentially masking the effects of ischemia on a solitary renal unit because serum creatinine and estimated glomerular filtration rate (GFR; which relies on serum creatinine) were used to assess renal function. In the largest study evaluating the effects of warm ischemia in 174 patients with a solitary kidney, we previously reported that warm ischemia >20 min was associated with an increased risk of acute renal failure (ARF) and chronic renal insufficiency (defined as serum creatinine >2.0 ng/dl) [5]. Limitations of this work included the fact that renal function was crudely estimated with serum creatinine alone, and adjustments for tumor complexity were not originally accounted for [11]. In this report, we update our collaboration to evaluate the short- and long-term renal effects of warm ischemia in a large cohort of patients with a solitary kidney.
Section snippets
Patient selection
Following approval from the institutional review boards, we identified 362 patients with a solitary kidney who had warm ischemia used during partial nephrectomy for renal cortical tumors between 1990 and 2008. Patients treated with no ischemia or cold ischemia were excluded. The surgical technique employed at the Mayo Clinic and Cleveland Clinic was summarized in 2007 [5]. It was common practice at both institutions to clamp both the artery and vein during hilar compression for warm ischemia,
Results
Baseline clinical and pathologic features and complications among all 362 patients are detailed in Table 1. Median age was 62 yr, and median tumor size was 3.4 cm. Median preoperative GFR was 61 ml/min per 1.73 m2, and 20 patients (6%) had a preoperative GFR < 30 ml/min per 1.73 m2. Median (range) preoperative serum creatinine was 1.2 (0.6–4.1) mg/dl. Hemorrhage and a postoperative urine leak were observed in 5% of patients each. Five patients (1%) had a positive margin after pathologic analysis. A
Discussion
To our knowledge, this is the largest report evaluating the renal consequences of warm ischemia time in patients undergoing partial nephrectomy in the setting of a solitary kidney. Compared with our previous results [5], we include more than twice as many patients (362 vs 174 treated with warm ischemia), we better assess renal function with estimated GFR according to the MDRD equation (as opposed to serum creatinine alone), and we include patients treated with both open and laparoscopic
Conclusions
Longer warm ischemia time is associated with short- and long-term renal consequences, including ARF and new-onset stage IV chronic kidney disease. Given the importance of preserving renal function, particularly in patients with a solitary kidney, every effort should be made to minimize warm ischemic intervals during partial nephrectomy, and research priority should be given to methods to improve renal surgical paradigms to minimize ischemic parenchymal damage.
Surgery is an essential treatment for most solid cancers and in the recent years the robotic-assisted surgery has become the first line treatment in urological tumors. The hemodynamic and respiratory impact of prolonged surgery time, steep trendelenburg position and pneumoperitoneum as well as the comorbidities that often characterize patients undergoing uro-surgery, are very challenging for the anesthesiologist. The aim of our review is to explore perioperative anesthetic considerations and provide tips to optimize the patient's preoperative clinical condition and to enable a rapid postoperative recovery.
Off-clamp nephron-sparing surgery (NSS) have been selectively performed in renal tumors in which the majority are T1a (<4 cm) renal caners. Less is known, however, whether off-clamp is a safe and effective option for treatment of Sporadic Renal Angiomyolipomas (RAML), especially in those >4 cm. The objective of our study was to compare the perioperative and renal function outcomes of a novel off-clamp tumor evacuation technique versus conventional laparoscopic NSS for the treatment of large sporadic RAMLs (>4 cm).
From January 2021 to June 2022, 42 patients diagnosed with RAML were prospectively randomized to receive laparoscopic standard NSS (Group 1) and off-clamp tumor evacuation (Group 2). The surgical and postoperative outcomes of both groups were compared.
Baseline characteristics demonstrated no discernible variation between Group 1 and Group 2. Compared to Group 1, Group 2 was associated shorter operative time (92.5 vs 82.3 min, p < 0.001), elimination of warm ischemic time (22.9 vs 0 min, p < 0.001), more blood loss (92.6 vs 161.9 ml, p = 0.02), and lower short-term renal function reduction of the operated kidney (17.2% vs 9%; p < 0.001). Neither major complication nor recurrence occurred.
It seems that transperitoneal laparoscopic off-clamp tumor evacuation is a feasible and safe option for the treatment of RAML, with the added benefit of preserving renal function to a greater extent than the traditional methods.
In partial nephrectomy for highly complex tumors with expected long ischemia time, renal hypothermia can be used to minimize ischemic parenchymal damage.
To describe our case series, surgical technique, and early outcomes for robot-assisted partial nephrectomy (RAPN) using intra-arterial cold perfusion through arteriotomy.
A retrospective analysis was conducted of ten patients with renal tumors (PADUA score 9–13) undergoing RAPN between March 2020 and March 2023 with intra-arterial cooling because of expected arterial clamping times longer than 25 min.
Multiport transperitoneal RAPN with full renal mobilization and arterial, venous, and ureteral clamping was performed. After arteriotomy and venotomy, 4°C heparinized saline is administered intravascular through a Fogarty catheter to maintain renal hypothermia while performing RAPN.
Demographic data, renal function, console and ischemia times, surgical margin status, hospital stay, estimated blood loss, and complications were analyzed.
The median warm and cold ischemia times were 4 min (interquartile range [IQR] 3–7 min) and 60 min (IQR 33–75 min), respectively. The median rewarming ischemia time was 10.5 min (IQR 6.5–23.75 min). The median pre- and postoperative estimated glomerular filtration rate values at least 1 mo after surgery were 90 ml/min (IQR 78.35–90 ml/min) and 86.9 ml/min (IQR 62.08–90 ml/min), respectively. Limitations include small cohort size and short median follow-up (13 [IQR 9.1–32.4] mo).
We demonstrate the feasibility and first case series for RAPN using intra-arterial renal hypothermia through arteriotomy. This approach broadens the scope for minimal invasive nephron-sparing surgery in highly complex renal masses.
We demonstrate a minimally invasive surgical technique that reduces kidney infarction during complex kidney tumor removal where surrounding healthy kidney tissue is spared. The technique entails arterial cold fluid irrigation, which temporarily decreases renal metabolism and allows more kidneys to be salvaged.
The superiority of off-clamp robot-assisted partial nephrectomy (RAPN) over the on-clamp technique has recently been questioned by randomized controlled trials comparing the two techniques.
To systematically review the recent literature and perform a quantitative synthesis of data on the comparison of off-clamp versus off-clamp hilar control during RAPN.
A systematic search was performed in the PubMed, Embase, Web of Science, and Scopus databases for studies comparing off-clamp versus on-clamp RAPN in terms of perioperative and functional outcomes. The study protocol was registered in the PROSPERO database (CRD42023413160). Only prospective randomized controlled trials and retrospective matched observational studies were included. The primary outcome of the study was the percentage decrease in the estimated glomerular filtration rate (eGFR).
A total of 11 studies were included involving a total of 2483 patients (944 patients in the off-clamp and 1539 patients in the on-clamp group). There was no difference between the two groups in the percentage decline in eGFR (mean difference [MD] 0.04%, 95% confidence interval [CI] −3.7% to 3.86%; p = 0.98). There were so significant differences between the groups for length of hospital stay (p = 0.56), complications (p = 0.08), conversion to open or radical surgery (p = 0.18), estimated blood loss (p = 0.06), or need for blood transfusion (p = 0.07). The operative time was shorter in the off-clamp group (MD−21.89 min, 95% CI −42.5 to −1.27; p = 0.04) but after sensitivity analysis the difference was no longer statistically significant (p = 0.15). The positive surgical margin rate was significantly lower in the off-clamp group (odds ratio 0.6, 95% CI 0.39–0.91; p = 0.02).
Our review revealed no clinically relevant differences in perioperative and functional outcomes between off-clamp and on-clamp RAPN.
In this review, we compared the two methods of controlling the kidney blood vessels during robot-assisted surgery to remove part of the kidney. We noted that there was no difference between the two groups for outcomes such as complications and the decrease in kidney function after surgery.
Tumors with a high nephrometry score represent a challenging surgical scenario for which robotic partial nephrectomy (RPN) is a primary option in expert hands.
To compare perioperative and functional outcomes of off-clamp and on-clamp RPN in patients with renal masses with a high RENAL score (≥9).
For this retrospective analysis, an RPN data set including 1604 patients treated at three institutions between 2003 and 2021 was queried for cases with a RENAL score ≥9.
We used 1:1 propensity score matching (PSM) to select a cohort in which imbalances between the off-clamp and on-clamp groups were minimized. We used χ2 and Student t tests to compare categorical and continuous variables, respectively. The Kaplan-Meier method was used to compare the probability of having an estimated glomerular filtration rate (eGFR) ≥45 ml/min during follow-up. Univariable and multivariable analyses were performed to identify predictors of a trifecta outcome (negative surgical margin status, no Clavien-Dindo grade ≥3 complications, eGFR decline ≤30%) and of retaining eGFR ≥45 ml/min over time.
From an overall cohort of 354 patients (142 on-clamp, 212 off-clamp), a homogeneous PSM cohort of 78 patients in each group was selected (p ≥ 0.17). In the PSM cohort, operative time was significantly shorter in the off-clamp group (p < 0.001). There were no differences between the groups in the rates of severe complications (p = 0.32) and positive surgical margins (p = 0.24). The rate of trifecta achievement was significantly higher in the off-clamp group (83.3% vs 67.9%; p = 0.03). Warm ischemia time >20 min was independently negatively associated with trifecta achievement (odds ratio 0.32, 95% confidence interval 0.14–0.74). Moreover, the off-clamp group had a significantly higher probability of retaining eGFR ≥45 ml/min over time (3 yr: 95.9% vs 81.6%; p = 0.03); every 1-min increase in warm ischemia time reduced this probability by 1.3%.
We found a favorable trade-off between the benefits and risks of off-clamp RPN, with similar perioperative outcomes and a net benefit in terms of trifecta achievement and long-term renal function outcomes in comparison to on-clamp RPN.
The complexity of surgery for kidney tumors can be assessed using the RENAL score, which is a measure of the location and size of a kidney tumor. In a multicenter series of patients with tumors with a high RENAL score, we compared outcomes between strategies with (on-clamp) and without (off-clamp) clamping of kidney blood vessels during robot-assisted removal of part of the affected kidney. We found that off-clamp surgery results in better postoperative kidney function.
