Effect of in vivo DDAVP on VWF, FVIII, and PFA. Whole blood was drawn before and at 2 and 4 hours after start of the DDAVP infusion in 93 patients with congenital platelet function defects. (A) Median VWF:RCo increased from 77% (IQR, 56% to 104%) to 236% (IQR, 186% to 292%) 2 hours after DDAVP and declined to 187% (IQR, 154% to 248%) at 4 hours (P < .001; Friedman repeated measures analysis of variance). (B) Median VWF:Ag increased from 80% (IQR, 63% to 112%) to 210% (IQR, 163% to 251%) and 175% (IQR, 142% to 228%) 2 and 4 hours after DDAVP, respectively (P < .001). (C) FVIII:C increased from 89% (IQR, 70% to 115%) to 204% (IQR,169% to 242%) and 167% (IQR,138% to 205%), respectively (P < .001). (D) PFA-system, epinephrine (EPI)/collagen. The closure time shortened from 159 seconds (IQR, 125 to 211 seconds) to 91 seconds (IQR, 77 to 105 seconds) 2 hours after DDAVP and slightly lengthened to 109 seconds (IQR, 90 to 129 seconds) at 4 hours (P < .001). (E) PFA system, ADP/collagen. The closure time with the ADP/collagen cartridge shortened from 101 seconds (IQR, 86 to 123 seconds) to 61 seconds (IQR, 54 to 70 seconds) and 66 seconds (IQR, 60 to 82 seconds), respectively (P < .001). Box plots visualize the median value (horizontal line within the box), the 25th and 75th percentiles (lower and upper borders of the box), the 10th and 90th percentiles (lower and upper whiskers), and each outlier outside the 10th and 90th percentiles (black circles). VWF:Ag, VWF antigen; VWF:RCo, VWF ristocetin-cofactor activity.