Continuous infusion of factor VIII (FVIII) concentrate is thought to maintain the level of FVIII in plasma more efficiently and to be safe and less expensive as compared with the conventional method. However, the assessment of the clearance rate of FVIII infused still remains to be solved for the management of hemorrhage during operation. In this study, we attempted to evaluate the clearance of infused FVIII concentrate over a period of 14 days after total joint arthroplasty conducted under the control of continuous infusion of FVIII concentrate based on the theoretical clearance rate of 2.5 units/kg/hr. The recovery rate was 108 % and the half life was 10.8 hours in 27 patients enrolled in this study. The averages of clearance rate and FVIII level in plasma on the day of operation were 2.84 U/kg/hr and 127.2 %, respectively, and those on day 13 after operation were 1.75 U/kg/hr and 96.6 %, respectively. These clearance rates appeared to be consistent with the theoretical value, and the estimated FVIII levels were rather higher than the levels expected. Although the FVIII concentrates had been kept at room temperature for 24 hours after dissolution, the FVIII activity was found to remain unchanged. We thus conclude that continuous infusion of FVIII concentrate based on the theoretical clearance rate seems to be legitimate for the management of hemorrhage for patients with hemophilia during major orthopedic surgery.

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