rpFVIII dosing algorithm currently used at our center. At diagnosis or presentation, we obtain a human and porcine BIA (hBIA and pBIA), as well as an FVIII level using a 1-stage clot-based assay (OSCA). Without waiting for the results of the pBIA, we dose rpFVIII at 100 U/kg, and draw a first-dose recovery level (R1) immediately after dosing. If R1 is at target (100% FVIII activity), then a 4-hour trough is obtained. We do not wait for the results of the 4-hour trough, but rather immediately administer a dose for 50 U/kg . If R1 is above target, we then delay drawing a trough until 6 to 8 hours after infusion depending on the degree of FVIII activity. If R1 shows some FVIII activity, but is <100%, we consider a repeat dose of 100 U/kg. Finally, if R1 is 0, we generally recommend changing therapy to a BPAs. Our practice is to dose to a goal trough of 30% to 50% with most bleeds, or 50% to 70% for severe, life-threatening events.