International Orthopaedics | 2021
Response to letter to the editor and comment concerning “Combined use of tranexamic acid and rivaroxaban in posterior lumbar interbody fusion safely reduces blood loss and transfusion rates without increasing the risk of thrombosis—a prospective, stratified, randomized, controlled trial”
Abstract
We appreciate the comments by Dr. Kong [1] and Dr. Dong [2] regarding our article titled “Combined use of tranexamic acid and rivaroxaban in posterior lumbar interbody fusion safely reduces blood loss and transfusion rates without increasing the risk of thrombosis—a prospective, stratified, randomized, controlled trial” [3]. Indeed, we are currently working on a follow-up study that should help answer many of these very important questions. The volume of autologous and allogenic transfusion was taken into account to calculate the total amount of blood loss. There is no such expression as “post-operative HCT on the first day after surgery” in the original text. The formula for calculating hidden blood loss is as follows: Hidden blood loss = Total blood loss + Blood transfusion volume—Dominant blood loss. Dominant blood loss = Intraoperative dominant blood loss + Total drainage volume. Total blood loss = PBV(pre-op) × (Hct pre-op—Hct postop)/ Average HCT. PBV = k1 × height3(m) + k2 × weight (kg) + k3. K1 = 0.3669, k2 = 0.03219, k3 = 0.6041 for men; k1 = 0.3561, k2 = 0.03308, k3 = 0.1833 for women [4, 5]. There were significant differences in BMI between groups A and B and groups C and D; however, there was no statistical difference in BMI between group A and group B, also with group C and group D. Therefore, we did not perform analysis of variance on the four sets of data, but used pairwise comparisons. Some scholars concluded that the effectiveness of TXA in reducing peri-operative blood loss in a dose-dependent manner. In our unpublished follow-up study, we also found this problem. The increase in the dose helps to better haemostatic effect. In this study, limited by the requirements for the dosage of tranexamic acid in the package insert and the review of the dosage by the ethics committee, we took a small dose and found that this is still effective. In follow-up research, we will further discuss the issue of dosage.