Effect Of Dexmedetomidine On Postoperative Renal Function In Patients Undergoing Cardiac Valve Surgery Under Cardiopulmonary Bypass

Object This study is aimed to investigate the effect of Dexmedetomidine（Dex）on postoperative renal function in patients undergoing cardiac valve surgery under cardiopulmonary bypass.Methods Seventy-eight patients who were scheduled to undergo cardiac valve replacement or valvuloplasty surgery under cardiopulmonary bypass were enrolled in this study in the Department of Cardiovascular Surgery of Fujian Medical University Union Hospital from July 2020 to December 2020.All patients were randomly divided into Dex group（group D）and Control group（group C）.All patients were treated with intravenous-inhalation anesthesia.Patients in Group D were intravenously injected with 0.6mg/kg/h of Dex from 10min before anesthesia induction to 6 h after surgery.Within 48 h after surgery,0.05mg/kg/h Dex was given by an analgesia pump combined with 0.06mg/kg/h sufentanil for patient-controlled analgesia（PCA）.The same procedure was also employed in group C by using normal saline instead of dexmedetomidine during the operation,PCA was given with 0.06mg/kg/h sufentanil by analgesia pump 48 h after surgery.Mean arterial pressure（MAP）was recorded 10 mins before anesthesia induction（T₀）,10 mins before CPB（T₁）,10 mins after CPB（T₂）,30 mins after CPB（T₃）,and at the end of surgery（T₄）.Heart rate（HR）were recorded at T₀、T₁、T₄.Arterial blood samples were collected at T₀、T₄ and 24 h after surgery（T₅）.Serum tumor necrosis Factor-α（TNF-α）,Interleukin-6（IL-6）,C-reactive protein（CRP）,Cystatin C（Cys-C）and central nervous system specific protein（S100-β）were determined at each time point.Arterial blood gas analysis of T₀ and T₄ was detected.The serum Creatine（Cr）was recorded before surgery,48 h after surgery and the highest one within 7 d after surgery.Blood Nitrogen（BUN）,Total bilirubin（TBIL）,Direct Bilirubin（DBIL）,Aspartate aminotransferase（AST）and cardiac troponin I（c Tn I）were recorded before surgery and 48 h after surgery.Left ventricular end diastolic（LVED）diameter and left ventricular ejection fraction（LVEF）were determined preoperatively and postoperatively.Intraoperative urine volume、blood transfusion volume、time of tracheal extubation and intensive care unit（ICU）stay、and incidence of related complications during hospitalization were recorded.Results According to the exclusion criteria,70 patients were finally selected from the two groups,and there were 35 patients in each group.There were no significant difference in preoperative and intraoperative general clinical data（P>0.05）.There were no statistically significant differences in the preoperative levels of Cr and BUN between the two groups（P>0.05）.At 48 h postoperatively,Cr and BUN in group D were lower than those in group C,and the maximum value of Cr within 7 d postoperatively was also lower than those in group C（P<0.05）.The incidences of AKI in group D and group C were 22.86%（8/35）and 48.57%（17/35;P=0.025）.In Group D,there were 6 patients in AKI grade 1,1 patient in AKI grade 2,1 patient in AKI grade 3,while in group C,there were 8 patients in AKI grade 1,6 patients in AKI grade 2,3patients in AKI grade 3.The severity of AKI in group D was less than that in group C（P=0.021）.TNF-a,IL-6,CRP,S100-βand Cys-C in both groups were increased to varying degrees compared with those before operation,and these changes were not all the same in different groups,different time points including the rate of change.And these in group D was lower than those in group C at T₄ and T₅（P<0.01）.Preoperative oxygenation index（OI）of two groups showed no statistically significant difference（P>0.05）,postoperative OI of two groups decreased,group D was higher than that in group C（388.60 vs.273.77）,the difference was statistically significant（P<0.01）.The differences of MAP and HR between the two groups were no statistically significant at T₀,T₄（P>0.05）.In T₁,T₂ and T₃,compared with group C,MAP in group D was lower than that in group C,with statistical significance（P<0.05）.At T₁,HR in group D（80.89±14.04 bpm）was lower than that in group C（95.54±12.53 bpm）,and the difference was statistically significant（P=0.022）.In terms of postoperative recovery,time of tracheal extubation、time of ICU stay and the total length of stay in group D were all shorter than those in group C,with a statistical significance（P<0.05）.In terms of adverse reactions,the incidences of tachycardia,hypertension,nausea and vomiting in group D were similar to these in group C,and the difference was not statistically significant（P>0.05）.Conclusion In patients undergoing cardiac valve surgery under cardiopulmonary bypass,dexmedetomidine can reduce the incidence and severity of postoperative AKI,speed up postoperative rehabilitation and do not increase the incidence of adverse reactions.The mechanism may be related to reduce TNF-a,IL-6,CRP and other inflammatory biomarkers、protect other organ functions and stable hemodynamics.