Bleeding and Leukaemia Flashcards
what is the process of haemostasis ?
injury and tissue damage, vascular response, platelet adhesion and aggregation, unstable platelet clot, coagulation factor cascade, fibrin, stable clot
what is the vascular response in haemostasis ?
vasoconstriction
what is the platelet response in haemostasis ?
VWF, platelet and fibrinogen —-> unstable platelet clot
what is the function of fibrin in clotting ?
give stability to the clot
what are the genetic coagulation defects ?
haemophila A,B,C, Von Willebrands
what are the acquired coagulation defects ?
drugs, liver disease, vitamin K deficiency, disseminated intravascular coagulation, massive blood transfusion
what clotting factor is deficient in haemophilia A ?
VIII
what clotting factor deficient in haemophilia B ?
IX
what clotting factor is deficient in haemophilia C ?
XI
when can haemophiliac A’s have dental treatment ?
straight after administration of factor VIII
when can haemophiliac B’s have dental treatment ?
factor IX has longer half life so can be given daily so treatment could be done at end of day
what is the treatment for haemophilia C ?
FFP, factor XI plus transexamic acid
what is Von Willebrands disease ?
similar to haemophilia A
how are people with Von Willebrands disease prepared for surgical procedures ?
minor - DDAVP and oral traexamic acid
major - factor VIII infusion
what considerations should be made before giving injections to haemophiliacs ?
regional blocks in floor of mouth may cause haemorrhage to track through tissue planes causing potential airway obstruction,
avoid intramuscular injections,
infiltrations fine for mild haemophiliacs
which anticoagulants are usually given for DVT’s and PE ?
heparin - immediate effect in acute thromboembolism
enoxaparin LMWH - inhibits factor Xa
newer drugs e.g. clexane
what is the mechanism of action of warfarin ?
impairs the synthesis of vitamin K dependent coagulase factors II, VII, IX, X in the liver
how long does warfarin take to become effective ?
2-4 days
what are the indications for short term oral anticoagulation ?
prevent DVT, MI 3 months, established DVT 3 months, xenograft cardiac valves 3 months, pulmonary embolism 3-6 months, CABG 2 months
what are the indications for long term oral anticoagulation ?
recurrent venous thromboembolism,
rheumatic heart disease and atrial fibrillation,
cardiac prosthetic valve replacement and arterial grafts
what is the scale for measuring INR ?
normal - 1 DVT, PE, AF - 2.5, recurrent DVT - 3.5, recurrent PE - 3.5, mechanical heart valves - 3.5
when should INR be checked prior to a procedure ?
no longer than 24-36 hrs before, preferably on the day
which drugs potentiate warfarin ?
miconazole oral gel (daktarin)
NSAIDS
what are the relevant drug interactions with anticoagulants ?
metronidazole - should be avoided or warfarin reduced by half
erythromycin - unpredictable effects in certain patients
how can INR be altered for planned surgery ?
stop 48 hrs before,
reduce warfarin by half for 48 hrs,
antibiotic or antifungal course
what are rivaroxiban and dabigatran ?
oral anticoagulants with no requirement for regular blood levels or INR
what is the mechanism of action of rivaroxiban ?
factor Xa inhibitor
what is the mechanism of action of dabigatran ?
direct thrombin inhibitor
what are rivaroxiban and dabigatran used for ?
hip, knee replacement prophylaxis (both)
stroke, AF, valve replacement (dab)
what are the anti platelet medications ?
low dose aspirin,
clopidogrel,
ticlopidine,
dipyridamole
what is low dose aspirin used to treat ?
thrombotic cardiovascular or cerebrovascular disease
what are clopidogrel and ticlopidine used to treat ?
symptomatic ischemic heart disease
what is dipyridamole used for ?
adjunct to oral anticoagulants with prosthetic heart valves
what is the mechanism of action of aspirin, clopidogrel and ticlopidine ?
inhibit platelet aggregation to blood vessel walls,
lasts for the life of the platelets 7-10 days
what is the mechanism of action of dipyridamole ?
reversible effect, acts directly on enzymes in platelets and vessel cell walls
which NSAIDs are used as anti platelet medications ?
ibuprofen, diclofenac - reversible
what causes coagulation defects ?
liver disease, hepatocellular failure, vitamin K deficiency, increased fibrinolysis, thrombocytopenia (low platelet count)
how is thrombocytopenia treated ?
autoimmune - treat with steroids or splenectomy,
leukaemia, aplastic anaemia - treat with platelet transfusion
what is leukaemia ?
neoplastic proliferation of WBC’s in bone marrow
what causes leukaemia ?
genetic - downs syndrome, ionizing radiation, chemicals - benzene, viruses, lymphoblastic and non lymphoblastic
what is acute lymphoblastic leukaemia ?
B lymphocyte neoplasm
what effect does chemotherapy have on bon marrow ?
leukopenia and neutropenia,
thrombocytopenia,
anaemia
what effect does chemotherapy have on the oral cavity ?
severe mucositis, oral ulceration, pseudomonas, candida albicans, herpes simplex
what are the recommendations for dental care prior to cancer therapy ?
comprehensive oral assessment, detailed OH instruction, chlorhexidiene, stabilise caries, remove teeth with doubtful prognosis
what are the recommendations for dental care during cancer therapy ?
hygienist available, chlorhexidiene, fluoride MW, alleviate xerostomia, prevent mucositis
when is prophylactic antibiotic cover recommended for patients having dental treatment during cancer therapy ?
if patient is neutropenic at time of treatment,
if treatment is likely to cause a significant bacteraemia
what should be checked before performing and extraction or surgical procedure on a cancer patient ?
platelet and white cell count
when would platelet cover be required in a cancer patient undergoing an extraction or surgical procedure ?
if the count is below 50X10^9 per litre
when should dental treatment be carried out on those having chemotherapy ?
before chemotherapy or 2-3 days after
when should platelets and neutrophils be checked ?
for procedures likely to cause bacteraemia
what are the risks of dental treatment to a patient undergoing chemotherapy ?
dental infections can be fatal on high doses of chemotherapy
