Renal ischemia time in laparoscopic surgery: an experimental study in a porcine model

Impact of short warm ischemic time on longitudinal kidney function and survival rate after partial nephrectomy for renal cell carcinoma in patients with pre-existing chronic kidney disease stage III: A multi-institutional propensity score-matched study

PURPOSE

It remains unclear whether a short warm ischemic time (WIT) improves long-term renal function after partial nephrectomy (PN) for patients with pre-existing chronic kidney disease (CKD). We evaluated renal function after PN according to WIT duration in patients with stage III CKD.

MATERIALS AND METHODS

We identified 277 patients with stage III CKD who underwent PN during 2004-2017. Propensity score matching was used to created two matched groups of patients: Group A (WIT of <25 min) and Group B (WIT of ≥25 min). The outcomes of interest were longitudinal kidney function change, new-onset stage IV CKD (eGFR <30 mL/min/1.73 m²) and overall survival.

RESULTS

The two matched groups contained 85 patients each. The median follow-up durations were 49 months in Group A and 42 months in Group B. The median pre-treatment eGFRs were 52.4 mL/min/1.73 m² in Group A and 52.6 mL/min/1.73 m² in Group B. There were no differences in kidney function between the two groups throughout the follow-up period (P > 0.05). The 5-year rates of new-onset stage IV CKD were not significantly different between Group A and Group B (8.2% vs. 7.1%), with no significant difference in the risk of developing stage IV CKD in Group A (vs. group B, hazard ratio: 0.527, 95% confidence interval: 0.183-1.521; P = 0.236). The 5-year overall survival rates were 90.3% for Group A and 96.2% for Group B (P = 0.549).

CONCLUSIONS

A short WIT was not associated with better postoperative kidney function or survival after PN in patients with stage III CKD.

Impacts of arterial ischemia or venous occlusion on vascularized groin lymph nodes in a rat model

BACKGROUND

Reported ischemia time of vascularized lymph nodes was 5 hours. This study investigated the effects of arterial ischemia and venous occlusion on vascularized lymph node function in rats.

METHODS

Bilateral pedicled groin lymph node flaps were raised in 27 Lewis rats. Femoral artery and vein were separated and clamped for 1, 3, 4, or 5 hour(s). Lymph node flap perfusion and drainage were assessed by laser Doppler flowmetry and indocyanine green lymphography. Histologic changes were assessed using hematoxylin and eosin stain, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), and glutathione assays.

RESULTS

Perfusion units of 2.84 ± 1.41, 2.46 ± 0.64, 2.42 ± 0.37, and 2.01 ± 0.90 were measured in arterial ischemia groups, and 1.71 ± 0.45, 2.20 ± 0.98, 1.49 ± 0.35, and 0.81 ± 0.20 in venous occlusion groups after 1, 3, 4, and 5 hours of clamping, respectively. Lymphatic drainage showed mean latency periods of 5.33 ± 0.88, 9.00 ± 3.21, 10.00 ± 2.08, and 24.50 ± 11.50 seconds in arterial clamping groups, and 25.00 ± 3.61, 26.00 ± 3.06, 23.33 ± 4.41, and 152.00 ± 0 seconds in venous clamping groups, respectively. Severe medullary and cortical congestion and hemorrhage on histology and cell damage by glutathione levels and TUNEL assay were found after 4 hours of venous clamping.

CONCLUSIONS

Arterial ischemia and venous occlusion impact the function and viability of vascularized lymph node flaps differently. The critical venous occlusion time was 4 hours.

Duplex scan and histologic assessment of acute renal injury in a kidney-kidney crosstalk swine experimental model

OBJECTIVE

The objective of this study was to identify the effect of two left renal vasculature occlusion strategies on the duplex ultrasound-assessed rheology and histology of the contralateral kidney.

METHODS

Pigs were randomly assigned to one of two groups: left renal artery-only clamping (A group, n = 8) or left renal artery and vein clamping (AV group, n = 9). Bilateral renal parenchymal biopsy specimens were taken every 10 minutes for 90 minutes. Duplex ultrasound resistive index (RI) and pulsatility index (PI) were measured. Mixed models with normal distribution and first-order autoregressive correlation structure and generalized estimating equation models were used. Results are presented as adjusted means with standard errors, estimated proportions with standard errors, and line plots with 95% confidence intervals.

RESULTS

RI and PI increased in the nonischemic kidney. In A group animals, RI values increased significantly (P < .01) after 30 minutes of ischemia and PI increased significantly (P < .04) from 30 to 60 minutes of ischemia. The number of histologic abnormalities was higher in A group than in AV group biopsy specimens. The percentage of lesions increased significantly after 10 minutes in A group nonischemic kidneys (P < .02) and between 50 and 80 minutes in AV group nonischemic kidneys (P < .01).

CONCLUSIONS

Nonischemic kidneys were acutely affected by contralateral ischemia. Their function was more adversely affected by unilateral renal artery occlusion with preserved renal vein patency (A group).

Ischemia/Reperfusion

Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.

Impact of ischaemia time on renal function after partial nephrectomy: a systematic review

OBJECTIVE

To assess the impact of ischaemia on renal function after partial nephrectomy (PN).

MATERIALS AND METHODS

A literature review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. In January 2015, the Medline and Embase databases were systematically searched using the protocol ('warm ischemia'[mesh] OR 'warm ischemia'[ti]) AND ('nephrectomy'[mesh] OR 'partial nephrectomy'[ti]). An updated search was performed in December 2015. Only studies based on a solitary kidney model or on a two-kidney model but with assessment of split renal function were included in this review.

RESULTS

Of the 1119 studies identified, 969 abstracts were screened after duplicates were removed: 29 articles were finally included in this review, including nine studies that focused on patients with a solitary kidney. None of the nine studies adjusting for the amount of preserved parenchyma found a negative impact of warm ischaemia time on postoperative renal function, unless this was extended beyond a 25-min threshold. The quality and the quantity of preserved parenchyma appeared to be the main contributors to postoperative renal function.

CONCLUSION

Currently, no evidence supports that limited ischaemia time (i.e. ≤25 min) has a higher risk of reducing renal function after PN compared to a 'zero ischaemia' technique. Several recent studies have suggested that prolonged warm ischaemia (>25-30 min) could cause an irreversible ischaemic insult to the surgically treated kidney.

Ineffectiveness of remote ischemic renal preconditioning in a porcine solitary-kidney model

PURPOSE

Our study sought to demonstrate the effects of remote ischemic preconditioning (R-IPC) on renal function in a large animal (porcine) solitary-kidney model.

METHODS

Twelve pigs were assigned to two groups: Each underwent a right nephrectomy followed by a week of recovery. Group 1 (No-IPC) underwent left renal hilar clamping for 90 minutes. Group 2 underwent right and left iliac artery clamping for 10 minutes each (R-IPC), followed by left hilar clamping for 90 minutes. Serum creatinine was drawn for both groups before ischemia (preoperative), then at 6 hours, 24 hours, 3 days, and 7 days after. Kidneys were harvested at 24 hours or 7 days for histologic analysis, and the degree of acute tubular necrosis (ATN) or lymphocyte invasion was quantified.

RESULTS

Paired serum creatinine values were analyzed between time points. For Group 1, paired differences existed at 24 hours (P=0.008) but not at 3 days or 7 days. For Group 2, paired differences existed at 24 hours (P=0.006) but not at 3 days or 7 days. The mean preoperative serum creatinine level was similar between groups (P>0.05). The change in serum creatinine level was not significantly different between groups at any time point. Histologic analysis revealed rare evidence of ATN at 24 hours in Group 2, but not in Group 1. At 7 days, neither group showed ATN, and both showed 1-2+evidence of lymphocytic infiltrates.

CONCLUSION

R-IPC in a solitary-kidney porcine model does not confer renal protection from warm ischemia either as evidenced by renal function measures or on histologic analysis.

Laparoscopic kidney transplant by extra peritoneal approach: the safe transition from laboratory to the clinic

The aim of this study is to develop a novel laparoscopic surgery by extra-peritoneal approach for kidney transplant and pave the way of safe transition from laboratory to the clinic. The study was established to explore the feasibility and safety of human laparoscopic kidney transplant. The experiment was first conducted on the deceased animals, then live animals and human cavader before human kidney transplant was approved. The study patient was a 49-year-old male who received the kidney for laparoscopic kidney transplant by extra-peritoneal approach. The control patient received the contralateral kidney for open kidney transplant. The estimated blood loss was minimal during surgery. Both kidneys experienced delayed graft function but the kidneys started function on Day 6 postoperation. The analgesia consumption was significantly less in the study patient. There is no surgical complication during 6-month follow-up. This study has developed a new technique for laparoscopic kidney transplant by extra-peritoneal approach. It has retained the advantages of open kidney transplant, which allows the graft located in the extra-peritoneal space without violating peritoneum. This study has also paved the way of safe transition for a novel laparoscopic surgery from laboratory to the clinic.

Carbamylated erythropoietin-FC fusion protein and recombinant human erythropoietin during porcine kidney ischemia/reperfusion injury

PURPOSE

To test the hypothesis that a carbamylated EPO-FC fusion protein (cEPO-FC) or recombinant human erythropoietin (rhEPO) would protect against kidney ischemia/reperfusion (I/R) injury in pigs with atherosclerosis.

METHODS

Anesthetized and mechanically ventilated animals received cEPO-FC (50 μg kg(-1)), rhEPO (5,000 IU kg(-1)), or vehicle (n = 9 per group) prior to 120 min of aortic occlusion and over 4 h of reperfusion. During aortic occlusion, mean arterial pressure (MAP) was maintained at 80-120 % of baseline values by esmolol, nitroglycerin, and ATP. During reperfusion, noradrenaline was titrated to keep MAP at pre-ischemic levels. Blood creatinine and neutrophil gelatinase-associated lipocalin (NGAL) levels, creatinine clearance, fractional Na(+) excretion, and HE and PAS staining were used to assess kidney function and histological damage. Plasma interleukin-6, tumor necrosis factor-α, nitrate + nitrite and 8-isoprostane levels were measured to assess systemic inflammation, and nitrosative and oxidative stress.

RESULTS

I/R caused acute kidney injury with reduced creatinine clearance, increased fractional Na(+) excretion and NGAL levels, moderate to severe glomerular and tubular damage and apoptosis, systemic inflammation and oxidative and nitrosative stress, but there were no differences between the treatment groups. Pre-ischemia nitrate + nitrite and 8-isoprostanes levels were lower and higher, respectively, than in healthy animals of a previous study, and immune histochemistry showed higher endothelial nitric oxide synthase and lower EPO receptor expression in pre-ischemia kidney biopsies than in biopsies from healthy animals.

CONCLUSIONS

In swine with atherosclerosis, rhEPO and cEPO-FC failed to attenuate prolonged ischemia-induced kidney injury within an 8-h reperfusion period, possibly due to reduced EPO receptor expression resulting from pre-existing oxidative stress and/or reduced NO release.

Cell biology of ischemia/reperfusion injury

Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.

Histological analysis and the blood flux in kidneys submitted to different periods of ischemia/reperfusion

PURPOSE: Evaluate the renal blood flow by using a laser flow meter, Laserflow Vasamedics®, after the ischemia/reperfusion in two different times of the arterial renal vessel clamping. METHODS: The renal blood flow was evaluated by using a laser flow meter after two different times of ischemia/reperfusion procedure, 30 and 60 minutes. It was used 20 Wistar male rats, divided in two groups of 10 rats: Group A (30 minutes of ischemia on the left kidney, with later analysis of the blood flow in 1, 5 and 20, after the renal reperfusion start) and Group B (60 minutes of ischemia on the left kidney, with later analysis of the blood flow in 1, 5 and 20 minutes, after the renal reperfusion start). RESULTS: In the first minute, there were not significant differences between the two groups (p=0.789). In the 5th minute there were not significant differences also, but there was a tendency (p=0.068). In the 20th minute, there was a significant difference between the 2 groups (p=0.022). When the means are observed, it is possible to notice that Group A has a larger flux than Group B. CONCLUSION: The kidneys submitted to 30' of ischemia/reperfusion are subject to a larger restitution of the blood flow in comparison to the Group which had a longer time.

Effect of sildenafil in renal ischemia/reperfusion injury in rats

PURPOSE

To evaluate the effect of sildenafil, administered prior to renal ischemia/reperfusion (I/R), by scintigraphy and histopathological evaluation in rats.

METHODS

Twenty-four rats were divided randomly into two groups. They received 0.1 ml of 99mTechnetium-etilenodicisteine intravenous, and a baseline (initial) renal scintigraphy was performed. The rats underwent 60 minutes of ischemia by left renal artery clamping. The right kidney was not manipulated. The sildenafil group (n=12) received orally 1 mg/kg of sildenafil suspension 60 minutes before ischemia. Treatment with saline 0.9% in the control group (n=12). Half of the rats was assessed after 24 hours and half after seven days I/R, with new renal scintigraphy to study differential function. After euthanasia, kidneys were removed and subjected to histopathological examination. For statistical evaluation, Student t and Mann-Whitney tests were used.

RESULTS

In the control group rats, the left kidneys had significant functional deficit, seven days after I/R, whose scintigraphic pattern was consistent with acute tubular necrosis, compared with the initial scintigraphy (p<0.05). Sildenafil treatment resulted in better differential function of the left kidneys 24h after reperfusion, compared with controls. Histopathologically, the left kidney of control rats (24 hours after I/R) showed a higher degree of cellular necrosis when compared with the sildenafil treated rats (p<0.05).

CONCLUSION

Sildenafil had a protective effect in rat kidneys subjected to normothermic I/R, demonstrated by scintigraphy and histomorphometry.

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.