Retrospective analysis of acute kidney injury after open heart surgery under cardiopulmonary bypass

Objective To investigate the effects of cardiopulmonary bypass(CPB) on renal functions.Methods The clinical data of 246 patients undergoing isolated CPB were analyzed retrospectively,combined with the relevant indexes of their surgery and renal functions,excluding hypertension,diabetes,hepatic and renal insufficiency,and preoperative administration of drugs of kidney toxicity.The patients were assessed and classified according to the definition of acute kidney injury(AKI) by the Acute Kidney Injury Network(AKIN) to compare the parameters among the AKI and non-AKI patients.The abbreviated MDRD equation was adopted to evaluate the estimated glomerular filtration rate(eGFR).Results Of the 246 patients,22 had AKI,with the prevalence rate of 8.9%,which was respectively distributed from phase 1 to 3 at the percentage of 6.1%,2.0% and 0.8%,respectively.Comparisons of all the indexes in both groups showed that the AKI patients were older than non-AKI patients(P0.05),while there were no significant differences in the levels of blood pressure,hemoglobin and renal functions before the operation in the two groups(P0.05).The AKI patients′s eGFR was(81.7±19.3) ml·min-1·(1.73 m2)-1,which was significantly lower than non-AKI patients(109.5±28.2)(P0.05).The pump time and ascending aorta blockage time of AKI patients were longer than those of non-AKI patients(P0.05).Within 24 hours after CPB,drainage volume of AKI patients was more than that of non-AKI patients,whereas urine volume decreased remarkably(P0.05).Conclusion The disadvantages leading to AKI in patients include old age,prolonged duration of CPB and ascending aorta blockage.MDRD equation was a useful strategy to estimate GFR for early detection of the patients at risk and prevention of AKI.