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Letter to the editor
Editor, – We refer to 'Dental notes: Managing dental patients receiving warfarin therapy' (Aust Prescr 2002;25:69). This commentary is unfortunate because it presents the historical approach to managing patients on warfarin therapy and does not reflect current best practice.
The key issue is the risk: benefit analysis of ceasing warfarin and risking thromboembolism, versus reducing it and risking local wound bleeding. Any logical analysis clearly comes down on the side that if warfarin is indicated and has been appropriately prescribed, then one should leave it alone. The real and potential risks such as stroke or myocardial infarction are clearly catastrophic events, whereas at worst local wound bleeding is messy and inconvenient.
There is an extensive body of research which shows that the appropriate management of patients on warfarin who require dentoalveolar surgery is as follows:
- preoperative - check INR the day before the procedure to ensure it is within the therapeutic range for the patient. If greater than 4.0, advise the patient's physician and delay surgery until the INR is within the therapeutic range.
- intraoperative - the use of a local anaesthetic combined with a vasoconstrictor, plus a controlled, minimally traumatic surgical technique and local haemostatic methods are recommended. This includes irrigating the operative field with a 4.8% tranexamic acid solution. The sockets and mucoperiosteal flaps should then be sutured and oxidised cellulose gauze placed in the sockets.
- postoperative - the patients should be given a 4.8% tranexamic acid mouthwash with instructions to rinse with 10 mL of the solution for two minutes four times a day for 2-5 days.
There are some issues of supply, although most major hospitals on appropriate request from the patient's pharmacy, are happy to supply tranexamic acid. The pharmacy of the Royal Adelaide Hospital is certainly willing and able to provide appropriate advice on this.
It is appropriate for the patient's dentist and the treating general medical practitioner to review the patient's anticoagulation therapy. In our studies, we found over one-third of patients on warfarin either no longer met the clinical indications for this therapy, or had an inappropriate dosage and thus either a sub-therapeutic INR or an INR above 4.
Alastair N. Goss
Oral & Maxillofacial Surgery Unit
The University of Adelaide
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