Massive bleeding is expected when performing distraction osteotomy for craniosynostosis patients. Since such operation is performed at very young age, many efforts are performed in order to reduce the total amount of bleeding and the transfusion during and after the surgery. Our study aims at correcting the coagulopathy from massive bleeding and transfusion during distraction osteotomy using continuous infusion of antifibrinolytic agent, tranexamic acid. Tranexamic acid infusion is determined according to the pharmacokinetic model, and the changes in coagulopathy will be defined using thromboelastography.

Inclusion Criteria:

1. Patients scheduled for distraction osteostomy under the diagnosis of Craniosynostosis.
2. Patients aged from 2 months to 6 years, either of whose patients had consented
3. ASA class 1 or 2

Exclusion Criteria:

1. Coagulopathy with either PT > INR 1.5 or PLT < 50,000/dL
2. Patients took any NSAIDs within 2 days, or aspirin within 14 days prior to surgery
3. History of convulsive seizure, epilepsy, any brain surgery
4. Known drug allergic reaction to tranexamic acid