Tuesday 25 July, 2006
How to stop warfarin for surgery
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
One would think that there would be guidelines on how, when or if warfarin should be ceased before surgery but the reality is that this is often not the case. I remember working as a surgical resident in the pre-operative clinic and having to make this decision on the fly. I can only hope that the anaesthetic registrar who conducted the (parallel) anaesthetic clinic knew what he or she was doing.
In a nutshell:
Low thromboembolic risk:
High thromboembolic risk:
See below for details |
Friday 30 June, 2006
How to reverse low molecular weight heparin
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
One of the benefits of using unfractionated heparin (UFH) by infusion over subcutaneous low molecular weight heparin (LMWH, e.g., enoxaparin sodium) is that reversal of UFH can be quickly done and is complete. Although LMWH can be mostly reversed by protamine sulfate it does have a small direct antithrombin effect that cannot be reversed. Furthermore, the subcutaneous adminstration is more difficult to reverse completely.
The use of protamine is non-trivial and best performed in experienced hands in a setting where monitoring is available.
Wednesday 28 June, 2006
How to reverse unfractionated heparin
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
Usually, if there is a concern of bleeding that is not life-threatening, cessation of unfractionated heparin (UFH) is enough. When given as an infusion, the anticoagulant effect of UFH reaches steady state within 4-6 hours. So on cessation of an infusion, coagulation should be mostly normally after 4 hours.
Where UFH is given subcutaneously for the purposes of venous thromboprophylaxis, the anticoagulant effect is more prolonged (but also milder considering the dose used).
In the case of an emergency, that is, an acute bleed in a patient anticoagulated with heparin, the antidote is protamine sulfate.
The use of protamine is non-trivial and best performed in experienced hands in a setting where monitoring is available.
Friday 23 June, 2006
How to reverse warfarin
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
Resources
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Warfarin is an increasingly commonly used medication in Australia. It is invaluable as an oral anticoagulant and until the oral direct antithrombin agents (e.g., ximelagatran) (1) are released, it is the only oral medication that can provide “therapeutic” levels of anticoagulation.
Unfortunately, with its increased use, over-anticoagulation has become a common presentation to the emergency department. A high INR with or without bleeding complication is not an uncommon scenario for hospital inpatients as well (IMHO due in part due to poor warfarin initiation and management).
Wednesday 21 June, 2006
How to use low molecular weight heparin
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
The most commonly used low molecular weight heparin (LMWH) in Australia is enoxaparin sodium (Clexane). The other that is available is dalteparin sodium (Fragmin).
Personally, I like enoxaparin. It is easy to use, there is less monitoring required and for the most part, it can be used for most patients. There is good evidence that the low molecular weight heparins are better than unfractionated heparin in many settings where (full) therapeutic anticoagulation is required, e.g., in the acute treatment of venous thromboembolic (VTE) disease (1) and in acute coronary syndromes (2).
Tuesday 20 June, 2006
How to use unfractionated heparin
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
Unfractionated heparin (heparin sodium) is commonly used in the acute care setting as an anticoagulant. Importantly, it does not contain any fibrinolytic activity so you cannot use it to break down clots (e.g., in lines).
Heparin is used for two purposes:
- Prophylaxis against venous thromboembolic disease (prophylactic dose);
- Full anticoagulation for treatment of thrombotic or thromboembolic disease (therapeutic dose).
Monday 19 June, 2006
Anticoagulation for prevention of venous thromboembolism
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
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Note: updated in June 2009 with the eighth edition (from the seventh) evidence-based clinical practice guidelines from the American College of Chest Physicians.
Prophylaxis against deep venous thrombosis (DVT) and venous thromboembolic (VTE) disease is an important part of modern medical and surgical treatment for the unwell or bed bound patient. There is high quality research with high grade evidence for many recommendations.
For the majority of patients, the following is usually appropriate:
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heparin 5000 units subcutaneously bd (tds for high risk) or enoxaparin 40 mg subcutaneously daily +/- graduated compression stockings |
Friday 16 June, 2006
How to start warfarin therapy
Index: Anticoagulation :: Printer friendly
Original article by: Michael Tam
Warfarin is an interesting medication – it saves many lives but causes many problems including some deaths of its own. At present, it is the only oral anticoagulant available in Australia and it is a commonly used drug. Warfarin management, however, is done notoriously badly in hospital.
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The key to warfarin management is patience |
The effective half-life ranges from 20 to 60 hours with a mean of about 40 hours (1). It takes around 3 half-lives to approach steady state and 5 half-lives to reach steady state. That is, for most patients it will take about a week before steady state is reached (and even longer for others). I have seen far too often in hospital people changing the dose of warfarin too rapidly with the result of the INR fluctuating up and down.
Wednesday 14 June, 2006
Schedule 2 and other forms
Original article by: Michael Tam
These forms are probably the ones most commonly used in acute psychiatry where a patient needs involuntary assessment or treatment. They are specific for New South Wales, Australia, only under the Mental Health Act (1990).
Click here for more information on the NSW mental health legal system.
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Resources
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Sunday 11 June, 2006
Fluid resuscitation
Index: Intravenous fluid therapy :: Printer friendly
Original article by: Michael Tam
There is only “one” rule for both adults and children:
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Normal saline :: 10-20 mL/kg bolus :: fast as you can |
If someone is shocked and requires emergency fluid resucitation, your fluid of choice is 0.9% NaCl or “normal saline”. Don’t fluff around with colloids or Hartmann’s solution – choose bog standard saline.
