Predictors of Acute Kidney Injury in the Postoperative Period of Cardiac Surgery Associated with Cardiopulmonary Bypass.

Introduction: Acute kidney injury (AKI) in the postoperative period of cardiac surgery occurs in 1 to 30% of the patients, mainly caused by ischemia secondary to renal hypoperfusion. Cardiopulmonary bypass (CPB) has a deleterious effect on renal function, constituting an aggression to the patient's homeostasis.

Aim: To evaluate the incidence of AKI in the postoperative period of cardiac surgery in patients without preoperative renal insufficiency who underwent cardiac surgery with CPB, and explore the association between incidence of AKI and predictors related to CPB.

Methods: Observational, retrospective, cross-sectional study. Participants were divided in two groups, those who developed AKI in the postoperative period and those who did not develop AKI. KDIGO Clinical Practice Guideline for Acute Kidney Injury classification was used to characterize AKI. The preoperative variables analysed were anthropometric data, cardiovascular risk factors and blood parameters. The type of surgery, intraoperative variables related to CPB and postoperative creatinine variation were also analysed. The association between variables was studied using binary logistic regression.

Results: Of the 329 patients included, 62 (18.8%), developed AKI. There were statistically significant differences between the groups in age (p<0.001), CPB time (p=0.011), diuresis during CPB (p=0.038) and mannitol and furosemide administration during CPB (respectively, p=0.032 and p=0.013). Odds ratio showed a significant positive association between AKI and age (OR (95%)- 1.08 (1.04-1.11)), CPB time (OR (95%)-1.01 (1.00-1.01)), mannitol and furosemide administration during CPB (respectively, OR (95%)-2.29 (1.08-4.89) and OR (95%)-2.54 (1.21-5.30)).

Conclusions: This study shows that a significant number of patients developed AKI in the postoperative period of cardiac surgery and this incidence was influenced by factors related to CPB.