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Poster Session 2

(630) Should Tranexamic Acid be Re-dosed for Patients with Postpartum Hemorrhage Based on Blood Volume?

Thursday, January 30, 2025
4:00 PM – 6:00 PM  
Objective: The objective of this study is to identify the relationship between blood loss and drug clearance and between blood loss and volume of distribution for tranexamic acid use at delivery to determine the need for scheduling subsequent doses at a fixed rate or based on the magnitude of blood loss.

Study Design: Four pharmacokinetic studies were reviewed, and estimates of drug clearance (CL) and volume of distribution in the central compartment (Vc) and the peripheral compartment (Vp) from prior modeling work were compared with volume of blood loss. Data from 205 individuals was divided into five equal groups based on volume of blood loss, ranging from 160 mL to 10 L. Then the relationships of interest were visualized and described. The data was further described by dividing it into clinically meaningful groups based on blood loss of < 1 L, 1-2 L, 2-3 L, and > 3 L. All data analysis and visualization were performed using R Statistical Software (version 4.2.2, R Core Team (2022), Viena, Austria, https://www.R-project.org/).

Results: Of the 205 individuals studied, 67 experienced blood loss of at least 1 L and ten experienced a blood loss of at least 2 L. Clearance and distribution were both identified to have a minimal relationship with volume of blood lost, with CL having a weak positive trend as shown in Figure 1 (R-squared of 0.44), and Vc and Vp having slightly negative trends (R-squared of 0.055 and 0.20, respectively). Figure 2 shows the trend generated by Vc and blood loss. Data derived from clinically meaningful groups were very similar to that previously described with R-square values for CL, Vc, and Vp equating 0.0061, 0.024, and 0.028, respectively.

Conclusion: No strong correlations were identified among the groups of interest, indicating that blood loss does not greatly affect the pharmacokinetic action of tranexamic acid. Therefore, there may be no need to base TXA redosing frequency on the magnitude of blood loss. Additional data in patients with blood loss >2 L would help to validate these findings.