Protective Effect Of Hypothermia In The Ischemic Area Of Selective Segmental Renal Artery Clamping

Objective:To investigate the protective effect of hypothermia in the ischemic area of selective segmental renal artery clamping(SSRAC),and to provide an experimental basis for the application of hypothermia in partial nephrectomy(PN)with preservation of renal units using SSRAC.Methods:From July 2020 to December 2020,a total of 6 experimental pigs were randomly divided into ice and normothermia group according to whether the hypothermia technique was used intraoperatively.All pigs had the right kidney removed after anesthesia,exposed the left kidney,then measure the temperature of the upper,middle and lower pole of the left kidney with a multiplex temperature detector by inserting a temperature probe vertically along the surface of the kidney,with T1,T2 and T3 probes corresponding to the non-ischemic area of the upper pole,the junctional area of the middle and the ischemic area of the lower pole of the kidney respectively,at an insertion depth of 15 mm.The temperature measured by the probe were recorded at immediately,5 min,20 min,35 min and 60 min after the lower pole branch of the left renal artery was clamped.In the ice group,ice-water saline pre-chilled to 4℃ was drip-fed to the perirenal area immediately after the clamping,the water level was maintained bellow the temperature probe,the ice-water saline was continuously removed and drip-fed to the perirenal area Intraoperatively,while the normothermia group was left untreated.The vascular clamps were removed after 60 min in both groups,and the surgical incision was closed layer by layer after confirming the restoration of blood supply to the ischemic area of the kidney.In all pigs,blood was drawn immediately before vascular clamping and on the1 st,7th and 14 th postoperative days to measure blood creatinine(SCr),urea nitrogen(BUN)and inflammatory factors(TNF-α,IL-6);The ICAM-1 expression level in the ischemic area of the kidney were measured by taking appropriate amount of renal tissue before ischemia,after 60 min ischemia and 24 h after reperfusion;the pathological examination of the left kidney was performed on the 14 th postoperative day to observe the pathological changes,and the observation indexes were the degree of glomerular and tubular epithelial cell injury and the infiltration of interstitial inflammatory cells.Results:All six pigs in the normothermia and ice groups completed the surgery successfully without serious intraoperative or postoperative complications,and all pigs survived at the 14 th postoperative day.Comparing the temperature of T3 probe in the ischemic area of the kidney between the two groups at 5,20,35 and 60 min after the clamping,the values were(21.4±0.4),(20.5±0.7),(18.5±0.6),(17.3±0.6)℃ in the ice group and that were(31.4±0.8),(30.2±1.4),(29.8±1.7),(28.6±1.6)℃ in the normothermia group,the values in the ice group were significantly lower than that in the normothermia group at every time point(P<0.05).Comparing the SCr values in blood on the 1th,7th and 14 th postoperative days between the two groups,the values were(147.57±33.89),(118.65±15.56),(101.71±8.02)μmol/l in the ice group and that were(241.95±33.77),(181.75±5.60),(136.16±15.48)μmol/l in the normothermia group,the values in the ice group were significantly lower than that in the normothermia group(P<0.05).Comparing the BUN values in blood on the 1th,7th and 14 th postoperative days between the two groups,the values were(13.47±3.14),(6.99±0.40),(6.46±0.42)mmol/l in the ice group and that were(241.95±33.77),(181.75±5.60),(136.16±15.48)mmol/l in the normothermia group,on the 1th postoperative day,the values in the ice group is significantly lower than that in the normothermia group(P<0.05),but on the 7th and 14 th postoperative day,there was no significant difference between the two groups(P>0.05).Comparing the TNF-α values in blood on the 1th,7th and 14 th postoperative days between the two groups,the values were(194.08±8.55),(112.69±17.09),(89.07±4.79)pg/ml in the ice group and that were(391.27±18.88),(592.55±20.27),(169.60±32.82)pg/ml in the normothermia group,the values in the ice group were significantly lower than that in the normothermia group(P<0.05).Comparing the IL-6 values in blood on the 1th,7th and 14 th postoperative days between the two groups,the values were(1899.81±241.90),(909.04±111.54),(521.68±181.35)pg/ml in the ice group and that were(5925.61±291.13),(2857.55±136.98),(1555.35±216.19)pg/ml in the normothermia group,the values in the ice group were significantly lower than that in the normothermia group(P<0.05).Comparing the expression levels of ICAM-1 of the renal tissues in the ischemic area of the kidney after 60 min ischemia and 24 h after reperfusion between the two groups,the values were(377.69±49.07)and(1151.13±161.81)ng/ml in the ice group and that were(839.24±53.40)and(2724.55±405.99)ng/ml in the normothermia group,the values in the ice group were significantly lower than that in the normothermia group(P<0.05).Comparing the pathological damage in the ischemic area of the kidney between the two groups,the ice group was significantly less than the normothermia group.Conclusions:During the application of SSRAC,take additional hypothermia measure such as perirenal ice-water saline technique is not only safe and feasible,but also can transform renal hot ischemia into cold ischemia,reduce the level of blood inflammatory factors and reduce the ischemia-reperfusion injury,to protect the renal function.