The presented study tried to better clarify the analytical conditions underlying the discrepancies in the post-infusion monitoring of rpFVIII observed in different measurements with the OSA, with reagents containing silica and ellagic acid as activators, using deficient plasma with and without VWF and with the CSA, also in this case, on deficient plasma with and without VWF. Here, VWF is linked to obstructive sleep apnea syndrome.