Effect of minimal increase in postsurgical creatinine on prognosis in patients undergoing cardiac surgery with cardiopulmonary bypass

The medical records of patients underwent thoracic surgery with cardiopulmonary bypass(CPB)from July 1, 2013 to May 30, 2014 were collected and reviewed, the patients who developed postsurgical acute kidney injury(increase in postsurgical serum creatinine>26.6 μmol/L)during hospital stay were excluded, and a total of 1 509 cases were enrolled in the study.Age, gender, body weight, presurgical complications, presurgical ejection fraction, serum concentration of creatinine on presurgical day 1, CPB duration during surgery, aortic clamping time, volume of blood transfused, duration of intensive care unit stay, mechanical ventilation time, length of hospital stay, and the highest serum concentration of creatinine were collected.The patients were divided into 2 groups according to the increase in postsurgical serum creatinine concentrations(the difference between the highest serum concentration of creatinine during hospital stay and the serum concentration of creatinine on presurgical day 1): no increase in creatinine group(n=508)and minimal increase in creatinine group(increase in postsurgical serum creatinine concentrations≤26.6 μmol/L, n=1 001). All the patients were followed up by telephone, and the fatality was recorded.Kaplan-Meier and log-rank analyses were used to analyze the survival condition, and the risk factors for fatality were identified by using multivariate Cox regression analysis.Compared with no increase in creatinine group, age was significantly increased, the constituent ratios of coronary heart disease, hypertension, diabetes mellitus, and pulmonary hypertension were significantly increased, CPB duration and length of hospital stay were significantly prolonged(P 0.05). The patients were followed up for(298±104)days, and Kaplan-Meier analysis showed that the long-term fatality rate was significantly higher in minimal increase in creatinine group than in no increase in creatinine group(P<0.05). Multivariate Cox regression analysis showed that age, presurgical coronary heart disease, CPB duration and minimal increase in postsurgical creatinine were the risk factors for fatality, and among these factors, minimal increase in postsurgical creatinine resulted in a 9% increase in the fatality rate.In conclusion, minimal increase in postsurgical creatinine can not only prolong the length of hospital stay, but also increase the long-term fatality rate in the patients undergoing cardiac surgery with CPB. Key words: Creatinine; Cardiopulmonary bypass; Cardiac surgical procedures; Prognosis