Haemostasis and thrombosis 2 Flashcards
which is the most common haemophilia
haemophilia A
what is the deficiency in haemophilia A
factor 8
features haemophilia A
severe spontaneous bleeding especially into joints- haemarthroses and muscles; onset in early childhood; chronic debilitating joint disease; pseudotumours
lab features haem A
PT normal, APTT incr, factor 8 decr, vwf normal
treatment haemophilia A
infusions factor 8- elevate platelets level to 20-50% normal for severe bleeding. desmopressin
inheritance haemophilia
sex linked
which factor is deficient in haemophilia B
9
inheritance haem B
sex linked. 4x less common than A, milder than A
treatment haemo B
factor 9 concentrate. desmopressin not effective
how is VWF disease inherited
autosomal dominant
role of VWF
carries factor 8in plasma and mediates platelet adhesion to endothelium.
if VWF or haemophilia A more common
VWF disease
features VWF disease
bleeding- from mucous membranes- mouth, epistaxis, menorrhagia. haemarthroses rare
lab findings in VWF
incr APTT, normal PT, factor 8 and VWF decr
treatment vwf
intermediate purity factor 8 concentrate- contains VWF and factor 8. if severe bleeding- high purity VWF concentrates. desmopressin, tranexamic acid
what can cause acquired disorders of coagulation
liver disease- defects in coagulation, platelets and fibrinolysis
what may reduced levels proteins C and S, anti thrombin and alpha2- antiplasmin lead to
DIC
what may dysfibrinogenaemia lead to
haemorrhage or thrombosis
what happens in DIC
release procoagulant material into circulation or endothelial damage- generalised activation coag and fibrinolytic pathways- widespread fibrin deposition
causes DIC
infection- septicaemia, meningitis, malaria; malignancy- promyelocytic leukaemia; obs- septic abortion, pre eclampsia, retained products of conception, amniotic fluid embolism; shock; hypersensitivity; burns; trauma
why do you get thrombosis and bleeding in DIC
as the coagulation process is consuming clotting factors and platelets normal clotting is disrupted so get severe bleeding
lab results DIC
platelets decr, PT incr, APTT incr, fibrinogen decr
treatment DIC
platelets if low platelets, cryoprecipitate if low fibrinogen, FFP to replace coag factors
if thrombosis predominates- DIC
anticoag?
effects DIC
widespread bleeding and thrombosis, acute resp distress syndrome, renal failure, liver dysfunction, GI bleeding, vaginal bleeding, skin ecchymoses and purpura, TE, gangrene
role of vitamin K
activate factors 2,7,9,10, and proteins C and S
what could lead to vitamin K deficiency
diet, broad spec antibios, biliary tract disease, intestinal malabsorption
why do newborns have haemorrhagic disease
immaturity of liver and low levels vit K. give IM vit K
what happens if patient has severe epistaxis but you check platelets and theyre normal
platelet function defect. treat with platelets
cause platelet function defect- inherited
inherited- Bernard-Soulier, Glanzmann, storage pool disease, VWF.
causes platelet function defect- acquired
drugs- aspirin, NSAIDs; myeloproliferative; uraemia; paraproteinaemia
what is dipyridamole
phosphodiesterase inhibitor- raises platelet AMP reducing their sensitivity to activating stimuli
what does fibrinolytic therapy do
enhance conversion plasminogen to plasmin which degrades fibrin
what does heparin do
activate antithrombin, impairs platelet function
why does heparin lead less to bleeding
greater ability to inactivate factor Xa less of an effect on thrombin and platelets
if LMWH needs monitoring (not usually)
factor Xa assay
how long does it take to fully coagulate starting warfarin
48-72 hours
what do you need to maintain INR at
2-3 but if high risk eg mechanical heart valves maintain at 2.5-3.5
how much vit K to give if haemorrhage
10mg IV
