Association Between Base Excess And Hospital Mortality In Patients Undergoing Coronary Artery Bypass Grafting

Objective to investigate the association between the minimum value of base excess(BEmin)and hospital mortality in patients undergoing coronary artery bypass grafting(CABG)and its correlation with major postoperative complications.And to explore the predictive efficiency of BE combined with lactate level in postoperative hospital mortality.Methods The clinical data of 1825 patients,including 1414 males and 411 females,who underwent isolated coronary artery bypass grafting under cardiopulmonary bypass from 2001 to 2012 in MIMICIII database were retrospectively analyzed.1)According to their survival conditions,they were divided into two groups:survival group and non-survival group.Multivariate logistics regression analysis was used to analyze the relationship between BEmin in the first 24 hours after operation and hospital mortality.2)Propensity score matching analysis was used to analyze whether BEmin≤-6.5 in the first 24 hours after operation was related to postoperative hospital mortality and major postoperative complications.3)The patients were divided into three groups by combining the minimum value of BE with the maximum value of lactate(LACmax):low risk group(BEmin>-6.5and LACmax<3.85)and medium risk group(BEmin>-6.5 and LACmax≥3.85;or BEmin≤-6.5 and LACmax<3.85),high risk group(BEmin ≤-6.5 and LACmax≥3.85).And then we evaluated whether combining BEmin with LACmax can improve the predictive ability of postoperative hospital mortality and whether it can be used as an indicator of risk stratification.Result 20(1.10%)patients who underwent simple coronary artery bypass grafting died in hospital.BEmin of the first 24 hours after operation in the non-survival group was significantly lower than that in the survival group(-8(-9 to-5)vs-3(-5 to-1)p=0.001).Multivariate logistics regression analysis showed that BEmin of the first 24 hours after operation was an independent predictor of postoperative hospital mortality.Propensity score matching analysis showed that the incidences of hospital death(4.57%vs 0.57%,p=0.018),delayed extubation(ventilator-assisted breathing time more than 24 hours)(29.14%vs 19.43%,p=0.034)and ventilator-assisted breathing time over 48 hours(20.00%vs 10.29%,p=0.011)in the patients with BEmin≤-6.5 of the first 24 hours after operation were significantly higher than that in the control group.And the ICU duration was also significantly higher than that in the control group(3.1(2.0-5.6)vs 2.2(1.3-4.2),p=0.003).The areas under the ROC curve of BEmin ≤-6.5,LACmax≥3.85 and their combination for postoperative hospital mortality were 0.79,0.80,0.87 respectively(p=0.0006).Their combination can improve the ability to predict postoperative hospital mortality.Compared with the low-risk group,the OR values of the medium-risk group and the high-risk group gradually increased,which were(OR:5.51%,1.31-23.22,0.020)and(OR:14.88,95%CI:3.36-66.02,p<0.0001),respectively.This can be used as a good indicator of risk stratification in the prognosis of patients.Conclusion BEmin in the first 24 hours after operation is an independent predictor of postoperative hospital mortality in patients undergoing isolated coronary artery bypass grafting under cardiopulmonary bypass.In the first 24 hours after operation,BEmin≤-6.5 is related to hospital mortality and some early postoperative poor prognosis.Combining BEmin with LACmax in the first 24 hours after operation can improve the ability to predict postoperative hospital mortality and also can be used as a good indicator of risk stratification.So clinicians need to take early and effective measures to adjust the BE to the normal level in order to improve the prognosis of patients undergoing CABG.