Continuous infusion factor replacement in haemophilia B during and after cardiac surgery: the better choice?

A 57-year-old man with mild haemophilia B was admitted for coronary artery bypass graft surgery. His factor IX (FIX) activity was 15% on admission. Our goal was to maintain his FIX activity at 80%–100% for post-op days (PODs) 0–3, and at 60%–80% for PODs 4–14. Preoperatively, the patient was given recombinant FIX (rFIX) bolus using the formula:Dosage needed=%(desired FIX level−current level of FIX)×weight (kg)×1.3.This increased his activity to 100%. One IU of rFIX increased FIX activity by 0.8%; the half-life of rFIX is 18–24 hours. The rFIX infusion was started intraoperatively and continued after surgery to maintain target FIX activity. He was discharged on POD 9 on rFIX bolus dosing of 5000 IU every 12 hours for an additional 5 days. Using continuous factor infusion, we managed to decrease the amount rFIX used by >60% while maintaining steady state FIX activity level.