Impact Of Fluid Balance And Low Cardiac Output Syndrome On Outcome Of Acute Kidney Injury Patients With Renal Replacement Therapy After Cardiac Surgery

Part One. Prospective Cohort Study of Acute Kidney Injury after Cardiac Surgery-Review Of4007CasesBackground Acute kidney injury (AKI) is a major complication following cardiac surgery and is associated with increased postoperative morbidity and mortality. There has been no research in summarizing this issue in Chinese people. The aim of the present study was to analysis the current situation of AKI in a synthetic teaching hospital in Shanghai to investigate the possibility of prophylaxis and treatment.Methods We prospectively collected data from4007patients who underwent cardiac surgery from April2009to May2011. Demographic characteristics, pre-and intraoperative general conditions, renal function, types of surgeries and clinical outcomes were recorded.Results Of the4007cases of cardiac surgeries, valve surgery occupies the largest proportion (52.2%), followed by coronary artery bypass graft (CABG) surgery (17.3%), congenital heart surgery (11.5%), combined surgery(8.7%, including CABG combined valve,4.1%; congenital heart surgery combined valve,4.6%), aorta surgery(5.9%), others(3.3%, including operation of pericardium and atrial myxoma), and orthotopic cardiac transplantation(0.9%). The overall incidence of AKI was31.2%(n=1250), RIFLE-R18.7%(n=750), RIFLE-I6.9%(n=275), RIFLE-F5.6%(n=225).The incidence of AKI requiring renal replacement treatment(AKI-RRT) was2.6%(n=104). The overall hospital mortality was1.9%, and was significantly higher in AKI group than in non-AKI group(5.4%vs.0.3%, P<0.001). The hospital mortality of AKI-RRT group was36.5%. Grouped by type of surgery, AKI incidence was highest in cardiac transplantation(73%), followed by CABG combined valve surgery(58%) and aorta surgery(52%). The hospital mortality was also highest in cardiac transplantation (18.9%),followed by CABG combined valve surgery(6.1%) and aorta surgery(5.5%).The AKI incidence and hospital mortality were lowest in congenital heart surgery. Multivariate logistic regression analysis showed that age (every10years), male, BMI, hypertension, heart failure, pre-operative SCr>1.2mg/dl, intra-operative cardiopulmonary bypass time, post-operative use of adrenaline were risk factors of AKI after cardiac surgery.Conclusions1) AKI and AKI-RRT incidence along with hospital mortality rate after cardiac surgery were high and close to researches in home and abroad. The incidence of AKI was related to a number of perioperative risk factors.2) The composition of surgery was different from that abroad, reflected in the larger proportion of valve surgery.3) Heart transplantation, aorta surgery, CABG combined valve surgery were high risk surgery. Part Two. Can Change of Cardiac Function after Cardiac Surgery Impact the Risk of AKI in Preoperative Renal Dysfunction Patients?—A Retrospective StudyObjective:Chronic kidney disease is accepted the risk factor of acute kidney injury. But the risk of AKI in preoperative renal dysfunction patients who is not accord with CKD diagnosis is not clear. We aimed to evaluate the risk of AKI of these patients by comparing the incidence of AKI of different kind or different extent of renal dysfunction.Method:Data from patients undergoing cardiac surgery and who had preexisting renal dysfunction (preoperative SCr>1.2mg/dl or eGFR≤60mL/min) from April2009to May2011were analyzed. Demographic characteristics, pre-and postoperative left ventricular ejection fraction (LVEF) and serum creatinine, preoperative NYHA functional class, eGFR, kidney ultrasound, history of proteinuria, history of kidney disease, complications, types of surgeries were recorded. AKI was defined according to the AKI Network classification. CKD was diagnosed according to KDOQI (2002). The patients were allocated into groups according to the postoperative cardiac function change or preoperative CKD diagnosis as following definitions:△LVEF=postoperative LVEF-preoperative LVEF. Cardiac function not improve (CFNI group)=△EF≤0%; Cardiac function improve (CFI group)=△EF>0%.Result:Of the317patients with preoperative renal dysfunction,257patients were male and60were female with a mean age of59±14years (range19to86). Preoperative NYHA functional class were grade Ⅱ(n=115), grade Ⅲ(n=165), grade Ⅳ (n=37). Pre-and postoperative LVEF were57±12%and59±11%, respectively. Pre-and postoperative serum creatinine was1.7±0.8and1.8±1.4mg/dl, respectively. Of the317patients, the incidence of AKI was47.3%(n=150), incidence of AKI requiring replacement therapy (AKI-RRT) was11%(n=35).Of the184patients in CFI group,38%(n=70) occurred AKI and9%(n=17) received RRT. Of the133patients in CFNI group,60%(n=80) occurred AKI and14%(n=18) received RRT. The AKI incidence and postoperative serum creatinine in CFI group was significantly lower than in CFNI group (38%vs60%, P<0.001;1.5±0.9vs.2.0±1.6mg/dL,P=0.005). There was no statistical significance in AKI-RRT incidence between the two groups.Of the63patients in CKD group,63%(n=40) occurred AKI and11%(n=7) received RRT. Of the254patients in no-CKD group,43%(n=110) occurred AKI and11%(n=28) received RRT. The AKI incidence and postoperative serum creatinine in no-CKD group was significantly lower than in CKD group (43%vs63%,P=0.004;1.7±1.4vs.2.2±1.3mg/dL, P=0.023). There was no statistical significance in AKI-RT incidence between the two groups (P>0.05)Further studied showed that in the no-CKD group with cardiac function improved subunit (n=149), the AKI incidence and postoperative serum creatinine were signficantly lower than in no-CKD without cardiac function subunit (n=105)(31%vs.51%, P<0.05;1.4±0.8vs.1.9±1.6mg/dL, P=0.014). While there was no statistical signficance in AKI-RRT incidence between the two groups(7.3%vs.14.7%,P>0.05). The postoperative serum creatinine was improved than preoperative in no-CKD group with cardiac function improved subunit (1.4±0.8vs1.7±0.9mg/dL,P=0.02). Multivariate logistic regression analysis showed that age, severe renal cyst, kidney shrinking, albuminuria, aorta surgery were independent risk factors of AKI after cardiac surgery in patients with preoperative renal dysfunction while improved cardiac function after surgery can reduce the risk.Conclusion:1)To patients with preoperative renal dysfunction, the AKI incidence is significantly lower in patients whose cardiac function improved after surgery than those not improved.2) To patients with preoperative renal dysfunction but without clear CKD diagnosis, as long as the postoperative cardiac function improved, the AKI incidence would be close to the normal population and postoperative renal function can be improved. Objective:We aimed to find out impacte of different period and extent of fluid accumulation to the outcome of patients with AKI requiring renal replacement therapy (RRT) after cardiac surgery.Method:Data from patients developed AKI and received RRT and stayed more than72hours in ICU after surgery from Jan2002to April2011were analyzed. Demographic characteristics, preoperative renal function, cardiac function, APACHE Ⅱ and SOFA score, length of hospital stay, length of ICU were recorded. Fluid intake and output was recorded since ICU admission. Fluid accumulation=(?)[daily fluid intake (L)-output (L)]; Percentage fluid accumulation=[(?)(daily fluid intake (L)-output (L)/body weight (in kilograms)]×100; Fluid overload (%FO)=percentage fluid accumulation≥10%over baseline weight; Not fluid overload (non-%FO)=percentage fluid accumulation<10%over baseline weight. Early ICU was defined as within48h from ICU admission after surgery. Late ICU was defined as after48h from ICU admission.Result:Of the172patients with AKI requiring RRT after cardiac surgery,117patients were male and55were female with a mean age of55±14years (range18to83). The average length of ICU stay and hospital stay were [13(6,31)] and [25(14,47)]. The average mechanical ventilation days was [18(4,21)]. The day-30mortality was43.6%(n=75). The fluid accumulation in different period after surgery of survivors was much more positive than non-survivors(P<0.05). The percentage of%FO in both ICU stay and early ICU in non-survivor group were significantly higher than in survivor group(P<0.01). Of the96patients (55%) in%FO group, the day-30mortality was significantly higher than non-%FO group (53%vs.32%, P=0.008). Of the55patients in early%FO group, the fluid overload of55%(n=30) patients was improved during the late ICU. But there was no statistical significance in the30-day mortality compared with those whose fluid overload did not improved (60%vs.63%, P=0.800). There were61patients occurred LCOS(Low Cardiac Output Syndrome) after surgery. The fluid accumulation in different period after surgery in LCOS group were significantly higher than in non-LCOS group(P<0.001). The day-30mortality was significantly higher in LCOS group than in non-LCOS group (69%vs.30%, P<0.001). There were55patients in early%FO subunit of LCOS group, the fluid overload of16patients was improved during the late ICU and the30d mortality was significantly lower compared with those whose fluid overload did not improved (53%vs.88%, P=0.031). Single logistic regression analysis showed that LCOS, ICU fluid overload, early ICU fluid overload, intra-operative cardiopulmonary bypass time were risk factors of death in AKI-RRT patients after cardiac surgery. Multivariate logistic regression analysis showed that LCOS was the only independent risk factor.Conclusion:1)Among patients with AKI requiring RRT after cardiac surgery, the fluid accumulation in different period after surgery of survivors was much more positive than non-survivors. The day-30mortality was increased with fluid accumulation.2) LCOS was the only independent risk factor. But if fluid overload in early ICU was improved during late ICU in LCOS patients, the day-30mortality could be reduced compared with those not improved. Thus improvement of cardiac pump function as well as early and intensive control of fluid balance for AKI-RRT patients after cardiac surgery was recommended. Part Four. Clinical Research on Goal-Directed Renal Replacement Therapy for Acute Kidney Injury after Cardiac SurgeryObjective To investigate the efficacy and safety of goal-directed renal replacement therapy(GDRRT) and daily hemofiltration (DHF) in treatment of patients with acute kidney injury (AKI) after cardiac surgery.Methods The clinical data of128patients developed AKI after cardiac surgery and treated with renal replacement therapy (RRT) from January2002to September2010were analyzed. Parameters such as urea nitrogen and serum creatinine were evaluated before and after treatment, heart rate, mean artery pressure (MAP) were recorded within72h after the initiation of RRT. The clinical outcomes such as hospital mortality, day-30mortality, renal recovery rate, incidence of adverse events were compared between the two groups.Results The hospital mortality of GDRRT group (n=64) and DHF group (n=64) were both43.75%. The day-30mortality were slightly lower in GDRRT group than in DHF group but without statistically significant (44%vs.58%, P=0.055). There was no significant difference in length of hospital stay between the two groups. The length of intensive care unit (ICU) stay in DHF group was longer than in GDRRT group (P=0.023). The mechanical ventilation days were longer in DHF group (P=0.042). The logistic regression analyses reported that renal completely recovery rate was significantly higher in GDRRT group than in DHF group (39%vs.19%, P=0.009). The renal partial recovery rate in GDRRT group was slightly lower than in DHF group but without statistically difference (3%vs.9%, P>0.05). During the RRT treatment both maximun serum creatinine (SCr) and the SCr before hospital discharge in DHF group were significantly higher than in GDRRT group (559.0±236.0vs.440.4±192.0μmol/L;381.4±267.0vs.271.2±164.4μmol/L, both P<0.01). Within72hour’s treatment there was no significant difference in hypotension incidence or mean artery pressure (mmHg,1mmHg=0.133kPa) in GDRRT group and DHF group (36%vs.38%,82±13vs.81±15mmHg, both P>0.05). The tachycardia and blood coagulation incidence were higher in DHF group than in GDRRT group (78%vs.60%;36%vs.20%, both P<0.05). The hospitalization expense was much high in DHF group than in GDRRT group (15000±2800vs.9850±3000, P<0.01)Conclusion1) Both goal-directed renal replacement therapy (GDRRT) and daily hemofiltration (DHF) can treat acute kidney injury after cardiac surgery effectively for the hospital mortality and day-30mortality were close to researches abroad.2) The short-term survival rate and safety of GDRRT are similar to that of DHF. The GDRRT therapy is superior to DHF in improving the renal recovery as well as the cost of therapy.