Flashcards in Acquired bleeding disorders Deck (20):
What are the causes of acquired bleeding disorders?
- Vit K deficiency
- Liver disease
- Massive transfusion syndrome
- Disseminated intravascular coagulation
- Acquired inhibitors
How can you tell if the bleeding disorder is due to a deficiency or the presence of an inhibitor?
- If activated partial thromboplastin time is prolonged repeat with 50:50 mix patient:normal plasma.
- Significant correction = deficiency
- No correction = inhibitor
Which coagulation factors will be affected by a vit K deficiency?
(2)II, (7)VII, (9)IX & (10)X
What are the possible causes of a vit K deficiency?
- Obstructive jaundice
- Prolonged nutritional deficiency
- Broad spectrum antibiotics
- Neonates (classical 1-7 days)
Why do patients with liver disease develop coagulopathies?
The liver is essential for the maintenance of normal level of coagulation factors.
What are patients with cirrhotic coagulopathy at risk of?
Severe bleeding from routine, invasive procedures (e.g. liver biopsies, dental extractions). Major source of morbidity and mortality in patients with liver disease.
What are the pathological features of impaired haemostasis in liver disease?
- Platelet dysfunction (plasmin induced cleavage of surface glycoproteins
- Reduced plasma concentration of all coagulation factors (reduced synthesis) except F(8)VIII
- Delayed fibrin monomer polymerisation due to altered fibrinogen glycosylation (xs sialic acid)
- Excessive plasmin activity
What is a 'massive transfusion'?
- Transfusion of a volume equal to the patient’s total blood volume in less than 24 hours
- 50% blood volume loss within 3 hours
What haemostatic abnormalities are possible in the case of a massive transfusion?
- Due to dilutional depletion of platelets and coagulation factors
- Due to DIC - risk factors are extensive trauma, head injury, prolonged hypotension
- Due to underlying disease, eg liver or renal drug treatment or surgery
What are the dilutional effects on haemostasis?
- Thrombocytopenia - at least 7-8 litres in adults usually transfused before problems are likely
- Coagulation factor depletion - mainly factors (5)V & (8)VIII and fibrinogen
- DIC common
- Citrate toxicity: uncommon - hypothermia and neonates - increased susceptibility
- Hypocalcaemia - no clinically significant effect on coagulation
What is the pathophysiology of DIC?
2. Local activation of coagulation
3. Intravascular coagulation
4. Consumption of clotting factors & platelets and fibrin deposition
5. Microvascular thrombosis: due to above leading to tissue ischaemia and organ dysfunction
6. Activation of fibrinolysis
7. Widespread bleeding elsewhere due to the consumption of clotting factors, activation of fibrinolysis etc
8. Microangiopathic haemolysis
What are the possible causes of acute DIC?
- Obstetric complications
- Trauma/Tissue necrosis
- Acute intravascular haemolysis eg ABO incompatible blood transfusion
- Fulminant liver disease
What are the possible causes of chronic DIC?
- End stage liver Disease
- Severe localised intravascular coagulation
- Obstetric : retained dead foetus
What laboratory tests are required in DIC?
- FBC and Blood film
- Coagulation screen: PT (70% prolonged), APTT (50% prolonged), TCT (usually prolonged)
- Fibrinogen Concentration
- FDP or D-Dimer (elevated in 85%)
- There is not one single diagnostic test: scoring systems are sometimes used.
How should DIC be managed?
Treat underlying cause:
- Obstetric intervention
- Chemotherapy/ATRA/tumour resection
- maintain tissue perfusion
- Co-ordinate invasive procedures
- (Folic acid and Vitamin K to support recovery period especially if illness prolonged)
- Platelet Transfusion if platelets 1.5: FFP 15ml/kg
Which drugs potentiate the Warfarin effect?
- Ampicillin (oral)
Which drugs anatgonise the Warfarin effect?
- Vitamin K
How should heparin be monitored?
- Anticoagulant effects of UFH can be monitored by tests sensitive to the anti-thrombin and/or anti-(10)Xa effects of heparin.
- For purposes of full anticoagulation with UFH, the APTT is most commonly used assay.
- Alternatives are: heparin level by protamine titration, heparin level by anti-(10)Xa assay, calcium thrombin time.
- In situations where it is desirable to monitor the effect of LMWH, anti-(10)Xa assays are used.
- The APTT is not sensitive to LMWH
Describe the management of bleeding due to overanticoagulation with heparin.
(1) Stop infusion
(2) Consider protamine administration 1mg neutralises 100IU of heparin Maximum 40mg.
(3) Effects of protamine on LMWH are less predictable and are complex