3. Blood clots Flashcards
xfTypes of venous thromboembolism
- Deep vein thrombosis
- Pulmonary embolism (life-threatening)
Deep vein thrombosis symptoms
- Swollen veins
- Hard and sore veins
- Unitlateral pain in legs
- Warm and red skin
Pulmonary emobolism symptoms
- Chest pain
- Dyspnoea
- Coughing up blood
Groups whom require VTE prophylaxis
- Immobility
- Obesity BMI >30
- Malignancy
- First-degree relative
- Pregnancy, post-partum
- Oestrogens
- Combined oral contraceptives
- Personal history
- Thrombophilic disorders
- Varicose veins with phlebitis
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Factors that increase a patient’s risk of bleeding
- Acute stroke
- Anticoagulants
- Sytolic hypertension
- Thrombocytopenia
- Bleeding disorders: liver failure, haemophilia, von willebrands
Thromboprophylaxis treatment
Two types
1. Pharmacological
2. Mechanical
1. Pharmacological
* DOAC oral
~7 days in general surgery
~28/30 days in major cancer surgery and spinal surgery respectively
* Heparin (parenteral)
Alternatively: Fondaparinux
Unfractionated heparin is offered in renal impairement
2. Mechanical
If Pharmacological interventions usuitable, mechanical can be used. Worn until mobile
- Pneumatic compression - inflatable sleeved worn on the legs
- Anti-embolic stockings
Should NOT be offered in acute stroke and legs conditions such as peripheral arterial disease
Hip and Knee replacement thromboprophylaxis
- For 35 days in hip replacement
LMWH + aspirin (10 days with further 38 days) OR LMWH + anti-embolism stockings
OR rivaroxaban - For 14 days in knee replacement
OR low dose aspirin for 14 days OR LMWH for 14 days WITH anti-embolism stockings - OR rivaroxaban
Apixaban or dabigatran can be used alternatively
Thromboprophylaxis and Venous thromboembolism treatment in pregnancy
Thromboprophylaxis:
LMWH + Pneumatic compression (if immbolised, alternatively: anti-embolism stockings)
Venous thromboembolism:
LMWH (unfractionated heparin if there is an increased risk of bleeding)
Venous thromboembolism treatment
Apixaban or Rivaroxaban
- For at least 3 months (or up to 6 months in active cancer, as cancer increases likelihood of developing blood clots)
- For unprovoked causes e,g combined oral contracepeptives, pregnant, leg cast: Around 3 months
Anticoagulants mechanism of action
Factor Xa Inhibitors:
* Oral DOAC: Apixaban, Edoxaban, Rivaroxaban
* Fondaparinux
* Heparins
Thrombin (Factor lla) inhibitiors
* Dabigatran
* Heparins:
Common errors associated with oral and parenteral anticoagulants
Dose
Wrong dose and duration
Wrong rate or frequency of parenteral anticoagulants
Drug-interaction
Duplication of therapy
Co-prescribing NSAID
Monitoring
Inadequate monitoring
Monitoring errors (lab values, vital signs)
Heparin uses and forms
Unfractionated heparin
Preferred if patient has HIGH risk of bleeding OR renal impairement (as it has a short half life so its effects can quickly be stopped, when discontinuing treatment)
LMWH e.g
tinzaparin
enoxaparin
dalteparin
It is Long-acting
lower risk of osteoperosis and thrombocytopenia
Heparin side effects
- Bleeding
Antidote: protamine - HyPERkalaemia
Heparins block aldosterone secretion in the renin-angiotensin system = hyperkalaemia
Patients with chronic kidney disease
Patients who have diabetes mellitus are at a higher risk of this
- Heparin-induced thrombocytopeonia
If this occurs, heparin should be STOPPED
Signs: skin allergy, thrombosis, reduced platelet count ~30% - Osteoporosis
Heparin interactions
-
Increased risk of HypERkalaemia, when taken with hyperkalaemic drugs:
ACE inhibitors/ARBs, aldosterone anatagonists e.g spiranolactone, Ciclosporin and tracrolimus, NSAID, potassium-sparing diuretic, potassium supplement, trimethoprim -
Increased risk of bleeding when taken with:
Anitcoagulants e.g warfarin, DOAC’s, antiplatelets, SSRI’s NSAID, Venlafaxine
Warfarin mechanism of action
Antagonises Vitamin-K
It takes 48-72 hours to work
Warfain indications
For venous thromboembolism and preventing a stroke in atrial fibrillation
Warfarin dose
Maintenance dose: 3-9mg daily
If a dose is missed, should take it as soon as they remember
0.5mg WHITE
1mg BROWN
3mg BLUE
5mg Pink
For isolated calf DVT: 6 weeks
Provoked VTE (by surgery, pregnancy, combined oral contraceptives): 3 months
Unprovoked VTE: 3+ months
Warfarin and pregnancy
Warfarin is teratogenic
Females of child-bearing age must take precautions
Warfarin monitoring
INR is meased every 12 weeks
unless there is a change in the clinical condition
TARGETS:
2.5: VTE, AF, MI, cardioversion, artificial valves
3.5:Recurrent VTE if on anticoagulant
Can afford to be within 0.5 units of targets
Warfarin can cause Calciphylaxis (calcium accummulating in small blood vessels of fat and tissue). Patients must reprt painful skin rash
More likely to occur in patients with end-stage renal disease. consider stopping.
Warfarin bleeding rules
If there is no bleeding
INR 5.0-8.0: Withold 1-2 doses of warfarin
INR>8.0: Oral phytomenadione
If there is bleeding
INR 5.0-8.0 OR INR>8.0: IV phytomenadione
Bleeding rules:
Patients must report nose bleeds >10mins, cuts that don’t stop bleeding, red urine, blood in vomiting, tarry stools, severe headaches, seizures
Warfarin counselling
Patients should be given a yellow booklet and an anticoagulant alert card (shown to doctors and dentists before procedures)
Food interactions:
Green, leafy, vegetables (should eat similar amounts regularly)
Alcohol binge increases risk of bleeding
Cranberry juice increases risk of bleeding
OTC interactions:
Miconazole, NSAID, Vitamin E and K supplements
- Avoid contact sports
- Use a soft toothbrush to avoid bleeding gums
Warfarin before surgery
Warfarin should be stopped 5 days before surgery
BUT
If patients are at a high risk of VTE, they can temporarily take a LMWH - bridging
If warfarin has not been stopped, in an emergency, IV phytomenadione can be used
Warfarin interactions
-
Interacts with drugs that also cause bleeding as a side effects:
Anticoagulants, Anti-platelet, SSRI’s, venlafaxine, tetracycline -
NSAIDs and warfarin interact
NSAIDs have a higher affinity for albumin than warfarin, displaces warfarin = more free warfarin in the blood = increased risk of bleeding -
Interacts with cytochrome P450 inhibitors = reduce warfarin metabolism = more warfarin in blood
Amiodarone, Azole antifungals, clarithromycin, erythromycin, metronidazole, quinolones, cranberry juice -
Interacts with cytochrome P450 inducers = increase warfarin metabolism = less warfarin in blood
Carbamazepine, Phenobarbital, Rifampicin, St John’s Wort
DOAC’s special conditions
Used for venous thromboembolism and for non-valvular AF
- Rivaroxaban - taken with food, only DOAC licensed to be crushed
- Dabigatran - comes in a special container, must be kept in the original container. It has a 4 month expiry
- Apixaban
- Edoxaban*
DOAC’S End in ban or tran