Episode 038: Hemophilia 101, Pt 3
In this episode, we discuss the acute management of the bleeding patient with hemophilia including factor replacement.
Some patients with a history of hemophilia and spontaneous bleeding have factor replacement at home and can treat themselves to 100% factor activity level.
*For Hemophilia A, 1 unit/kg of factor 8 replacement will increase the factor level activity by 2%. So, 50 units/kg will raise the factor activity from 0% to 100%
*For Hemophilia B, 1 unit/kg of factor 9 replacement raises factor level activity by 0.75%. So, 130 units/kg raises the factor level from 0% to 100%.
**If the patient does not know their baseline factor levels, assume factor level activity is less than 1%. Replace to 100% for a major, life-threatening bleed.
**Give factor replacement BEFORE you get imaging.
When do you give more factor replacement?
The goal is to keep the patient in the normal range of 50-150% factor activity level. The half-life of the factor replacement is about 12 hours. So, this means that if you replace to 100%, 12 hours later, you’ll need another 50% replacement dose. Get trough levels q24 hours before the morning dose.
Remember that trough levels are not useful in patients taking Emicizumab. Emicizumab is the bispecific monoclonal antibody that binds to factor 9 & 10 activating the latter. This essentially replacing the role of factor 8, which is missing in hemophilia A.
If the patient has an inhibitor, you can overwhelm the coagulation system with activated factor 7, which bypasses the intrinsic pathway to form a clot.
Particularly for mucosal bleeding, you can use an antifibrinolytic agent (tranexamic acid, aminocaproic acid) which stabilizes the clot and prevents the breakdown of fibrin mesh.
Another treatment for patients with milder forms of hemophilia is DDAVP, which release stores of Factor 8 and Von Willebrand Factor from the blood vessel endothelium. Side effects include hyponatremia and fluid retention.
If you are in a hospital with no specific factor replacement, you can use cryoprecipitate, which contains fibrinogen, factor 8, factor 13, & Von Willebrand Factor.
The crew behind the magic:
Show outline: Madeline Fitzpatrick
Production and hosts: Ronak Mistry, Vivek Patel, Dan Hausrath
Editing: Vivek Patel
Shownotes, graphics, social media management: Ronak Mistry
