prolonged bleeding Flashcards
what is prolonged bleeding
- anything that goes on for more than 12 hours
- anything that causes pt to return to emergency unit
- something that results in a hematoma (blood clot) or ecchymosis (bruising)
- something that requires a blood transfusion
what are the different causes of haemostasis disorders
- congenital
- acquired
what are the acquired causes of haemostasis disorders
iatrogenic:
anti-platelets e.g. aspirin, clopidogral, diprydamole
anti-coagulant- warfarin, apixaban, rivaroxaban
renal failure:
renal failure is associated with impaired platelet function - platelets can adhere abnormally to blood vessels
hepatic failure:
the liver is the major source of soluble clotting factors :. hepatic failure is reduced synthesis of these clotting factors II, VII (hemophilia A), IX & X
Bone marrow failure:
bone marrow makes platelets
:. bone marrow failure= less platelets
bone marrow also makes erythrocyts- RBC :. anaemia
bone marrow failure can be due to:
chemotherapy
alcohol abuse
renal failure
leukemia
what are the congenital causes of haemostasis disorders
usually rare and not common in dental practice
Abnormalities of Soluble Coagulation Factors
* Haemophilia A (congenital reduction in factor VIII);
* Haemophilia B (congenital reduction in factor IX);
* von Willebrand’s Disease (congenital reduction in von Willebrand’s factor).
Abnormalities of Platelets
* All rare – (e.g. Glanzmann’s syndrome)
Abnormalities of Blood Vessels
* Hereditary Haemorrhagic Telangiectasia
how would you measure disordered haemostasis
prothrombin time (P.T) and INR (International normalised ratio)
P.T- A venous sample of blood is used to measure P.T
P.T is mainly determined by the activity of clotting factor V11
INR is measured by = pts PT/mean PT of a healthy group
what is a healthy INR
1.0 - this is in healthy people
people on anti-coagulants such as warfarin should have an INR of 2-4 to qualify for XLA
what should the INR be for someone on anticoagulant for them to qualify for XLA
2-4
what is APTT
activated partial thromboplastin time- important in the assessment of heparin anticoagulation
what are the 2 consequences of prolonged bleeding
acute haemorrhage
chronic haemorrhage
What questions would you ask in medical history to rule out hemostasis disorders in the dental practice?
‘Have you ever had any problems in the past with stopping bleeding after cutting yourself, after dental care or following operations?’;
* ‘Do you bruise easily?’; and
* ‘Are you prone to nose bleeds?’.
if they say they have had prolonged bleeding after an XLA ask further q’s e.g
When did the prolonged bleeding occur?;
* On how many occasions?;
* Have there been problems since or before the episode?;
* Were there any local factors that might have contributed to the prolonged bleeding (e.g. local infection or local soft tissue trauma)?
* How was the situation managed?;
* Were any investigations or special tests undertaken and what were the results of these?
establish if they have any liver disease
how does haemostasis occur
- collagen exposed
-platelet aggregation
-clotting factors XII,XI, IX,VII
-prothrombin goes to thrombin - fibrinogen goes to fibrin
when do you give antiplatelets
tx or prevention of CVD e.g. high cholesterol, and previous history of ischaemic stroke
what are some examples of anti-platelets
aspirin
clopidogral
what is the mechanism of aspirin (antiplatelet)
- Aspirin binds irreversibly to platelets
- It inactivated COX-1 enzyme (cyclooxygenase) which is needed for thromboxane A2 mediated aggregation
what is the mechanism of clopidogral
- Clopidogrel binds to the P2Y12 receptor irreversibly and prevents Adenosine Di Phosphate (ADP) mediated aggregation
- This effect occurs within hours and persists throughout the lifespan of the platelet (~7-10 days)
how frequently are platelets renewed
every 10 days
do NSAIDS e.g. ibuprofen have antiplatelet activity
yes, but its binding is reversible
why do you not give NSAIDS after an extraction
it has anti-platelets properties e.g. ibuprofen
should you stop aspirin before an extraction
it takes weeks for the effects to be reversed and the risks of thrombotic effects in the pt is not worth it
can you give aspirin to children under16
no- risk of reyes syndrome- rare condition causing swelling of liver and brain
what is thrombocytopenia
reduction in platelets
what is the normal platelet amount
150,000-450,000/ml
in which conditions do you have a reduced platelets amount
leukaemia, anaemia, pregnancy, chronic alcohol abuse, medication (anticonvulsants, sulfa -antibiotics), ITP (Idiopathic Thromobocytopenia)
what is echymosis
bruising
what is a low/unsafe platelet count
anything belo 80,000/ml
how would you manage low platelet
may require corticosteroids
when do you prescribe warfarin
DVT (deep vein thrombosis), PE (pulmonary emboism) , atrial fibrillation (abnormal atrial firing)
what vitamin does warfarin depend on to act as an anticoagulant
vitamin K
what vitamin is used to reverse the effects of warfarin
vitamin D
what is the mechanism of warfain acting as an anticoagulant
- Antagonises the synthesis of factors II, VII, IX and XI in the liver
what do warfarin takers carry on them
a yellow book with their INR
what is the half life of warfarin and what does that mean
48 hours :. the INR reading is the dose you took 2 days ago
what does a high INR mean
thinner blood :. more risk of haemorrhage (blood loss)
what does a low INR mean
thicker blood :. more risk of thrombosis
what herbal medicines/foods interfere with warfarin
- Ginseng
- St Johns Wort
- Green tea (rich in vit K)
- Liver
- Broccoli
- Brussel sprouts
- High oxalate greens like spinach, * Alcohol
coriander and cabbage * Grapefruit - Pomegranate juice * Cranberry juice
what should you be careful of for pts on warfarin
Avoid NSAIDs and COX-2 inhibitors which add further to prolong bleeding
what does tranxemic acid do
Tranexamic acid acts at the stage of conversion of plasminogen to plasmin in the clotting cascade leading to reduced fibrinolytic and reduced clot digestion - i.e. it promotes clotting
good for people on warfarin
