S18C230 - Hemophilias and von Willebrand Disease Flashcards
hemophilias are caused by factor deficiencies
-most common being factor VIII (hemophilia A) or factor IX (B)
Sx of platelet dysfunction:
- easy bruising
- gingival bleeding
- epistaxis
- hematuria
- GIB
- heavy menses
Sx of coag factor deficiency:
- spontaneous deep bruises
- hemarthrosis
- retroperitoneal bleeding
- intracraneal bleeding
Features of both platelet and coag deficiency:
vWD
hemophilia
- A : deficiency in factor VIII
- B : deficiency in factor IX
- clinically indistinguishable
- make up 99% of inherited coag factor deficiencies
- x-linked (therefore men get it)
- may not have FmHx b/c often a spontaneous mutation
- severe dz: usually spontaneous bleeding
- moderate: usually a traumatic event occurs
- mild: only bleed with trauma
- pts do not have problems with minor scrapes and cuts
- for severe unexplained bleeding send lab tests and treat with FFP
- delayed bleeding after dental extraction common but no spontaneous bleeding from oropharynx
Hemophilia: Dx
- normal Prothrombin time (extrinsic cascade)
- aPTT will be abnormal (intrinsic cascade)
- however if enough factor around the aPTT may be normal despite an overall deficiency
- bleeding time will be normal
- need a specific factor assay
Hemophilia: Tx
- if abdo pain/back pain think iliopsoas bleed (pt keeps hips flexed, externally rotated, may compress femoral nerve)
- if localizing neuro sx consider MRI of spinal cord
- compartment syndromes
- common manifestation is hemarthrosis
- do not place central lines w/o replacing factors first, same with IM injections
- do not give ASA or NSAIDs
- factor replacement therapy for any acute bleed
Factor Replacement Therapy
- recombinant form is best, plasma-derived may still contain viruses despite being treated
- one unit of factor represents the amount of factor present in 1 mL of normal plasma
- factor VIII 1/2 life is 8-12h
- 1/2 life of factor IX is 16-24h
- know that pts may have inhibitors (antibodies against replacement factors), consult a hematologist
Mild hemophilia A
- if mild bleeding present they may not require factors
- can give desmopressin which releases vWF from endothelial cells which then can carry incrased amoutns of factor VIII in the plasma
- desmopressin 0.3mcg/kg over 15-30mins
- there is an intranasal form, single spray one nostril for 5-12yo, spray in each nostril for teenagers (300mcg total dose) q8h but VIII stores will become deplete and fluid restriction will be necessary b/c of antidiuretic effect
hemophilia and hematuria
- if persistent then give factor VIII
- if Sx, go looking for cause
Von Willebrand Disease
-present in 1% of popn
-abnormality in vWF, heterogeneously inherited
-3 major groups:
Type 1: partial quantitative dz (tx w desmopressin)
Type 2: qualitative (abnormal fxn) (cryoprecipitate of vWF concentrate)
Type 3: severe and complete deficiency of vWF (tx same as 2)
-vWF is synthesized, stored and secreted by vascular endothelial cells, it is a cofactor for platelet adhesion and carrier protein for factor VIII (thereby increasing its 1/2 life)
-vWF binds glycoprotein Ib on cell matrix and then binds platelets
VWD - clinical picture
- skin and mucosal bleeding is common
- recurrent epistaxis, gingival bruising, unusual bleeding, GIB, menorrhagia
- if severe, may have hemarthrosis
vWD - dx
- tests: bleeding time, aPTT, factor VIII coag activity, vWF antigen, vWF activity
- prlonged bleeding time
- low or normal vWF antigen
- low vWF activity
- prothrombin time normal
- 1/2 of pts will have a mildly prolonged aPTT
- blood type (O) affects measurement of vWF
vWD - Tx
- avoid antiplatelet meds
- desmorpressin for type 1
- type 2/3: plasma product containing vWF - cryoprecipitate
- can consider platelet transfusion (for type 3) if no response to vWF plasma products
- menorrhagia: OCP can raise vWF levels
- tooth extraction bleed: TXA, may be used for 5-10d after surgery
cryoprecipitate contains:
- factor VIII and vWF
- risk of viral transmission
- may need 10 bags q12-24h
