The influence of the contralateral kidney upon recovery from unilateral warm renal ischemia

Effect of unilateral renal ischemia on the contralateral kidney assessed by Caspase 3 expression

Background

Studies have demonstrated with histological analysis and Doppler flow measurement analysis that unilateral renal ischemia, which is performed in some surgeries, interfered with the contralateral kidney, identifying the phenomenon of kidney-kidney crosstalk.

Objectives

To identify the effects on the ischemic and contralateral kidney of renal ischemia induced by two types of clamping technique by analyzing the volume of kidney cells positive for Caspase 3.

Methods

Sixteen pigs were divided into 2 groups, as follows: A (n = 8) – clamping of left renal artery only and AV (n = 8) – clamping of left renal artery and vein. Immunohistochemical analyses (anti Caspase 3) were conducted with biopsy specimens collected from the ischemic and contralateral kidney at 0, 30, 60, and 90 minutes of ischemia and morphometric analysis was performed, taking the mean to represent the volume of the Caspase 3 positive area (%).

Results

Morphometric analysis of specimens collected at 30, 60, and 90 minutes of ischemia showed that the mean area marked for Caspase 3 was statistically larger in the contralateral kidney than the ischemic kidney in both groups: clamped renal artery (A) and clamped renal artery and vein (AV). Comparing the ischemic and contralateral kidney, there was no statistically significant difference in the area marked for Caspase 3 between the two types of clamping.

Conclusions

In the experimental model of unilateral renal ischemia, the non-ischemic kidney exhibited cell damage, demonstrated by Caspase 3 expression. The type of hilum clamping does not appear to influence the area marked for Caspase 3.

A novel rodent model of severe renal ischemia reperfusion injury

Renal ischemia reperfusion injury (IRI) is a major problem, currently without treatments in clinical use. This reflects the failure of animal models to mimic the severity of IRI observed in clinical practice. Most described models lack both the ability to inflict a permanent reduction in renal function and the sensitivity to demonstrate the protective efficacy of different therapies in vivo. To test novel cell-based therapies, we have developed a model of renal IRI in Fisher 344 rats. Animals were subjected to 120 min of unilateral warm ischemia, during which they underwent an intra-renal artery infusion of therapeutic agents or vehicle. At either 2 or 6 weeks post-surgery, animals underwent terminal glomerular filtration rate (GFR) studies by inulin clearance to most accurately quantify renal function. Harvested kidneys underwent histological analysis. Compared to sham operations, saline treated animals suffered a long-term reduction in GFR of ≈50%. Histology revealed short- and long-term disruption of renal architecture. Despite the injury severity, post-operative animal losses are <5%. This model produces a severe, consistent renal injury that closely replicates the pathological processes encountered in clinical medicine. Renal artery infusion mimics the route likely employed in clinical transplantation, where the renal artery is accessible. Inulin clearance characterizes GFR, allowing full assessment of therapeutic intervention. This model is useful for screening therapeutic agents prior to testing in a transplant model. This reduces animal numbers needed to test drugs for clinical transplantation and allows for refinement of dosing schedules.

Renal Ischemia and Function After Partial Nephrectomy: A Collaborative Review of the Literature

CONTEXT

Partial nephrectomy (PN) is the current gold standard treatment for small localized renal tumors.; however, the impact of duration and type of intraoperative ischemia on renal function (RF) after PN is a subject of significant debate.

OBJECTIVE

To review the current evidence on the relationship of intraoperative ischemia and RF after PN.

EVIDENCE ACQUISITION

A review of English-language publications on renal ischemia and RF after PN was performed from 2005 to 2014 using the Medline, Embase, and Web of Science databases. Ninety-one articles were selected with the consensus of all authors and analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria.

EVIDENCE SYNTHESIS

The vast majority of reviewed studies were retrospective, nonrandomized observations. Based on the current literature, RF recovery after PN is strongly associated with preoperative RF and the amount of healthy kidney parenchyma preserved. Warm ischemia time (WIT) is modifiable and prolonged warm ischemia is significantly associated with adverse postoperative RF. Available data suggest a benefit of keeping WIT <25min, although the level of evidence to support this threshold is limited. Cold ischemia safely facilitates longer durations of ischemia. Surgical techniques that minimize or avoid global ischemia may be associated with improved RF outcomes.

CONCLUSIONS

Although RF recovery after PN is strongly associated with quality and quantity of preserved kidney, efforts should be made to limit prolonged WIT. Cold ischemia should be preferred when longer ischemia is expected, especially in presence of imperative indications for PN. Additional research with higher levels of evidence is needed to clarify the optimal use of renal ischemia during PN.

PATIENT SUMMARY

In this review of the literature, we looked at predictors of renal function after surgical resection of renal tumors. There is a strong association between the quality and quantity of renal tissue that is preserved after surgery and long-term renal function. The time of interruption of renal blood flow during surgery is an important, modifiable predictor of postoperative renal function.

Renal histopathology features according to various warm ischemia times in porcine laparoscopic and open surgery model

BACKGROUND

Thirty minutes has been considered as the threshold for tolerable warm ischemic time (WIT). Recent reports demonstrate recovery of renal function after longer WIT. We assessed renal histology according to different WIT in a 2-kidney porcine model.

METHODS

Twelve female pigs were randomized to an open or laparoscopic group. Each pig was further randomized within each group to clamping the left renal artery for 5, 15, 30, 45, 60 or 180 minutes. Preclamping left renal biopsies were performed on each pig. The contralateral kidney in each animal was used as an individual control. On postoperative day 14, all animals underwent bilateral nephrectomies. Preclamping left renal biopsies and all renal specimens were evaluated by a blinded veterinary pathologist.

RESULTS

One pig died in the open group after 180 minutes of clamping. Histopathology did not show any significant changes between the two groups and across clamp times from 5 to 60 minutes. After 180 minutes of laparoscopic clamping, there was evidence of diffuse necrosis.

INTERPRETATION

Sixty minutes of ischemia did not show any permanent renal damage in both groups. Further studies are needed to verify these findings in humans. A prolonged ischemic time without permanent renal damage would be helpful in partial nephrectomy. Warm ischemic time of 180 minutes exceeded the renal ischemic burden based on histological features.

Every minute counts when the renal hilum is clamped during partial nephrectomy

BACKGROUND

The safe duration of warm ischemia during partial nephrectomy remains controversial.

OBJECTIVE

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 m(2) within 30 d of surgery. Among the 226 patients with a preoperative GFR >or=30 ml/min per 1.73 m(2) and followed >or=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.

The Impact of Ischemia Time During Open Nephron Sparing Surgery on Solitary Kidneys: A Multi-Institutional Study

PURPOSE

The safe duration of ischemia during nephron sparing surgery remains controversial. We performed a multi-institutional study to evaluate the renal effects of vascular clamping in patients with solitary kidneys.

MATERIALS AND METHODS

Using the Cleveland Clinic and Mayo Clinic databases, we identified 537 patients with solitary kidneys who underwent open nephron sparing surgery. Renal complications were compared among patients who did not require vascular clamping (85), and those who had warm ischemia (174) and cold ischemia (278).

RESULTS

Median patient age (63, 65, 64 years) and preoperative creatinine (1.4, 1.3, 1.4 mg/dl) were similar among patients with no ischemia, warm ischemia and cold ischemia, respectively. Median tumor size was smaller in patients with no ischemia (2.5 cm), compared to patients with warm (3.5 cm) and cold (4.0 cm) ischemia (p <0.001). Warm and cold ischemia was associated with a significantly increased risk of urine leak (p = 0.006), acute (p <0.001) and chronic (p = 0.027) renal failure, and temporary dialysis (p = 0.028) compared to patients with no ischemia. Warm ischemia longer than 20 minutes and cold ischemia longer than 35 minutes were associated with a higher incidence of acute renal failure (p = 0.002 and p = 0.003, respectively). Additionally, warm ischemia more than 20 minutes was associated with an increased risk of chronic renal insufficiency (41% vs 19%, p = 0.008), increase in creatinine greater than 0.5 (42% vs 15%, p <0.001) and permanent dialysis (10% vs 4%, p = 0.145).

CONCLUSIONS

Vascular clamping during open nephron sparing surgery is associated with a higher incidence of renal complications. Attempts to limit warm ischemia to 20 minutes and cold ischemia to 35 minutes should be used when vascular clamping is necessary.

Laparoscopic warm renal ischemia in the solitary porcine kidney model

OBJECTIVES

To determine the effect of a laparoscopic approach on warm renal ischemia in the pig with a solitary kidney. Although the maximal safe duration for warm ischemia during open partial nephrectomy is commonly accepted to be 30 minutes, the maximal safe ischemic time during laparoscopic partial nephrectomy has not been previously determined.

METHODS

Sixteen farm pigs underwent unilateral laparoscopic right nephrectomy. Two weeks later, the pigs underwent complete laparoscopic mobilization of the remaining left kidney and were randomized to complete hilar clamp times of 0, 30, 60, or 90 minutes. Serum creatinine was evaluated before right nephrectomy and at days 0, 2, 4, 7, 14, and 30 after renal ischemia during laparoscopy. All renal specimens were evaluated by an experienced nephropathologist in a blinded fashion.

RESULTS

The serum creatinine remained stable at all points in the control and 30-minute ischemia groups. The serum creatinine level rose initially on days 2 and 4 in the 60-minute and 90-minute ischemia groups but returned to baseline by day 7. At harvest, no statistically significant difference was found among the groups in serum creatinine or histologic features.

CONCLUSIONS

Renal ischemic times up to 90 minutes during laparoscopy were well tolerated by the solitary porcine kidney. Possible explanations for this finding include the protective effect of a solitary kidney and the potential protective effect of relative ischemic preconditioning provided by the pneumoperitoneum.