Serum Lactate and Capillary Refill Time as Predictors of Acute Kidney Injury After Pediatric Cardiovascular Surgery: A Prospective Cohort Study

Abstract Background Acute kidney injury (AKI) is a frequent complication after pediatric cardiovascular surgery (CVC) and is associated with higher morbidity and mortality. Early, modifiable predictors are needed to improve outcomes. Methods We conducted a prospective cohort at a high-complexity center in Cali, Colombia (November 2020–July 2022). Children aged 0–60 months undergoing CVC and admitted to the pediatric cardiovascular ICU were included. AKI was defined and staged by KDIGO criteria. Serum lactate and capillary refill time (CRT) were measured pre-operatively, at ICU admission, and at 6, 12, and 24 hours post-operatively. We compared clinical, intra- and post-operative variables between patients with and without AKI using appropriate univariate tests and logistic regression. Results Of 131 patients, 19.1% developed AKI; 69.2% of AKI cases were severe. Twenty-eight-day mortality was 15.3% overall and 52% among patients with AKI. Higher surgical complexity by RACHS-1, elevated serum lactate at 6–12 hours post-op, and prolonged CRT at all time points were associated with AKI. Lactate at admission (OR 2.88; 95% CI 1.2–7.0), 6 h (3.63; 1.5–9.0) and 12 h (2.84; 1.1–7.1), and prolonged CRT at admission (2.09; 1.0–4.2), 6 h (2.10; 1.2–3.7) and 12 h (2.42; 1.4–4.2) were significant predictors. Conclusions In this cohort, postoperative tissue-perfusion markers—elevated serum lactate and prolonged CRT—were associated with AKI following pediatric CVC. These accessible bedside measures may support early risk stratification and targeted kidney-protective strategies.