Many patients with hemophilia A do not know exactly how much coagulation factor VIII needs to be transfused when they bleed, so you can find out from the following. 1. Factors for determining the dose: ①basic level of FⅧ:C of the patient; ②severity of bleeding; ③site of bleeding; ④existence of inhibitors; ⑤perfection of other hemostatic and coagulation mechanisms; ⑥blood volume of the patient; ⑦effectiveness of the products used; ⑧half-reduction period of coagulation factors, etc. Peng Jie, Department of Hematology, Xiangya Hospital, Central South University 2. Calculation by formula: In the absence of FⅧ inhibitors, 1 unit (U) of FⅧ products per kilogram of body weight per infusion can increase the level of FⅧ (FⅧ:C) in the circulating blood of patients by 2%. The formula for calculating the amount of FⅧ product required per infusion is: Unit (U) = patient’s body weight (kg) × (target FⅧ:C hemostasis level % – measured FⅧ:C level %) × 0.5. Example: If the patient’s body weight is 50 kg, the target FⅧ:C level is 50%, and the measured FⅧ:C level is 1%, the amount of FⅧ product required (U) = 50 × (50 – 1) × 0.5 = 50 (-1) × 0.5 = 50 × 49 × 0.5 = 1,225 U/time. 3. Dose of FⅧ products: The dose of FⅧ products should be determined according to the patient’s bleeding level and the actual measured level of FⅧ:C. The level of FⅧ can be increased to >50% for bleeding at special sites. Dose and course of plasma products for hemophilia A patients with bleeding