[Correlation of carbon dioxide derived parameters during cardiopulmonary bypass with acute kidney injury after pediatric cardiac surgery].

Objective: To explore the correlation of the ratio of venous-arterial carbon dioxide (CO2 ) tension difference to arterial-venous O2 content difference (Pv-aCO2 /Ca-vO2 ) and venous-arterial CO2 gradient (Pv-aCO2 ) during cardiopulmonary bypass (CPB) with acute kidney injury (AKI) after pediatric cardiac surgery. Methods: The clinical data of children (1 month ≤ age ≤ 3 years old) who underwent open heart surgery under CPB in West China Hospital of Sichuan University from March 2021 to August 2022 were retrospectively analyzed. All paired blood gases of the children during CPB (the sampling time interval of arterial and venous blood was within 10 minutes) were collected. According to the Failure, Loss, End-Stage Renal Disease (pRIFLE) diagnostic criteria, the children were divided into AKI group and non-AKI group. Multivariate logistic regression analysis was performed to identify the risk factors of postoperative AKI in pediatric cardiac surgery. Results: A total of 213 children were enrolled (101 males and 112 females), aged 12(6, 24) months, and 84 of them (39.4%) developed AKI. Three children died in AKI group, with a mortality of 3.6%. There were no deaths in non-AKI group. The incidence of postoperative low cardiac output syndrome (LCOS) was higher in AKI group [29.8% (25/84) vs 7.0% (9/129), P <0.001]. In addition, compared with the non-AKI group, children in AKI group had longer recovery time [15 (6, 78) h vs 6 (3, 19) h, P <0.001], mechanical ventilation time [17 (7, 97) h vs 6 (4, 20) h, P <0.001], intensive care unit (ICU) stay [6 (4, 11) d vs 3 (2, 5) d, P <0.001], and hospital stay [12 (9, 18) d vs 9 (8, 11) d, P <0.001]. A total of 317 arterial and venous blood gas pairs from 30 ( n =207), 60 ( n =75) and 90 min ( n =35) after aortic clamping were included in the analysis. Univariate analysis showed that Pv-aCO2 /Ca-vO2 ( P =0.015) at 30 min after aortic clamping, Pv-aCO2 ( P =0.041) and Pv-aCO2 /Ca-vO2 ( P =0.014) at 60 min after aortic clamping, peak Pv-aCO2 ( P =0.009), peak Pv-aCO2 /Ca-vO2 ( P <0.001) and the average value of Pv-aCO2 /Ca-vO2 ( P =0.001) were higher in AKI group. Multivariate logistic regression analysis showed that longer duration of CPB ( OR =1.013, 95% CI : 1.003-1.023, P =0.012), higher peak Pv-aCO2 /Ca-vO2 ( OR =1.337, 95% CI : 1.037-1.723, P =0.025) were risk factors for AKI. Conclusion: The occurrence of AKI after pediatric cardiac surgery is related to the short-term adverse clinical prognosis, and longer duration of CPB and higher peak Pv-aCO2/ Ca-vO2 are independent risk factors for AKI.