Abstract
AIMS: Tranexamic acid (TXA) stabilizes clot formation by inhibiting fibrin degradation and improves postoperative outcomes. However, rare adverse events (e.g., thrombosis, seizures) warrant dose-risk evaluation. This study examines how perioperative blood loss and transfusion practices affect TXA concentrations during paediatric scoliosis surgery. METHODS: Forty-three patients undergoing scoliosis surgery with TXA were retrospectively analysed. The study assessed the impact of packed red blood cell (PRBC) transfusion on plasma TXA levels and whether maintaining concentrations ≥10 μg/mL correlated with intraoperative blood loss. TXA levels were measured using UHPLC-MS/MS. RESULTS: Median TXA concentration 30 min after the loading dose was 37.8 μg/mL (IQR: 31.4-39.6 μg/mL), decreasing to 10.6 μg/mL (IQR: 9.7-13.5 μg/mL) after transfusion. At surgery end, the mean concentration was 12.9 ± 2.5 μg/mL. Thirty-one patients maintained TXA levels ≥10 μg/mL, associated with ~80% inhibition of tissue plasminogen activator. Of six patients below this threshold, five had received transfusions. A significant correlation was found between higher intraoperative blood loss and lower TXA levels, consistent with a dilutional effect. In contrast, among patients with TXA ≥ 10 μg/mL, correlation with blood loss was weak (Spearman's ρ = -0.11, p = 0.54). Findings suggest homologous PRBC transfusion reduces plasma TXA through volume expansion. CONCLUSIONS: Sustaining TXA concentrations >10 μg/mL is essential for antifibrinolytic efficacy and haemostatic outcomes. The dilutional impact of PRBC transfusion underscores the need for intraoperative dose adjustment. Optimizing TXA dosing requires understanding pharmacokinetics and patient variability.