Neuraxial Anesthesia and Anticoagulants
This will be a review of when to hold and restart commonly seen anticoagulation in regards to epidural and spinal procedures, maintaining epidural catheters, and removing catheters.
One potential complication of neuraxial anesthesia when someone is on an anti-clotting medications is some sort of hemorrhagic complication, like an epidural or spinal hematoma. While the chances of this happening are very rare, the rate of this complication increases with difficulty during needle placement and coagulation abnormalities. With the rise of patients on anticoagulation for various reasons such as Dual-AntiPlatelet Therapy (DAPT) after a heart attack or Warfarin (Coumadin) for atrial fibrillation, the American Society of Regional Anesthesia and Pain Medicine (ASRA) created a collection of guidance for how to handle medications around the timing of neuraxial anesthesia. The timing falls into 4 categories: when to stop the drug prior to the procedure, when to restart the drug after the procedure, when to hold the medication prior to catheter remove, and when to restart the medication after catheter removal. Just a reminder, the catheter portion only refers to epidural catheter - spinals are single shot without a catheter and nerve block catheters have their own set up guidelines less stringent than epidural catheter placement and removal.
Vitamin K Antagonists, such as Warfarin, disrupt the function of factors II, VII, IX, and X. Bleeding occurs when any of the factors is below 20-40% of their baseline. An INR greater than 1.4 is usually associated with less than 40% activity of Factor VII, leading to potentially inadequate clotting. Neuraxial injections and removing an epidural catheter is safe within the first 24 hours of initiating Warfarin treatment. It must stopped 5 days prior to a neuraxial procedure. An INR less than 1.5 is also considered safe for neuraxial procedures.
When patients are admitted to the hospital, particularly for surgery, they are started on a deep vein thrombosis (DVT) prophylaxis regimen. This usually involves subcutaneous injections of heparin or low-molecular weight heparin (lovenox). When using heparin subcutaneous (5,000U BID), it must be held 4-6 hours prior to a neuraxial injection (12 hours for high dose 7500-10,000U bid or daily). After the epidural catheter is removed, you can restart subcutaneous heparin immediately. If subcutaneous lovenox is used, you must hold it for 12 hours prior to a neuraxial procedure. After removing the epidural catheter, you should wait at least 4 hours before restarting lovenox. If the patient has been receiving heparin or lovenox in the hospital for at least 4 days, you should check a platelet level to rule out heparin-induce thrombocytopenia (HIT). The risks and benefits should be addressed when deciding if to continue the DVT prophylaxis with an in dwelling epidural catheter
If the patient is on therapeutic doses for heparin and lovenox for a DVT or pulmonary embolism (PE), the timing is a bit more stringent. For therapeutic subcutaneous heparin, you should hold it for 24 hours prior to a neuraxial injection. After removing an epidural catheter, you can restart heparin immediately. For IV heparin, you can hold it 4-6 hours with a normal PTT prior to a neuraxial procedure. After removal of an epidural catheter, you can restart IV heparin in one hour. For therapeutic lovenox, you must hold it for 24 hours. After removing an epidural catheter, you can restart lovenox in 4 hours.
Dabigatran (Pradaxa) is an oral agent that binds to reversibly inhibits free and clot-bound thrombin. It is usually dosed once daily with a prolonged half-life of up to 17 hours after repeated doses. Because of this long half-life, it is recommended to hold dabigatran at least 5 days prior to a neuraxial procedure. After removing an epidural catheter, you can restart dabagatran in 6 hours. If a patient is urgently taken to surgery and is on dabigatran, there is a reversal agent (Idarucizumab) that can be used to bind dabigatran and make it inactive.
Factor Xa inhibitors like Rivaroxaban (Xarelto) and Apixaban (Eliquis) are other common drugs used to treat chronic blood clots. They should be held 3 days (72 hours) prior to a neuraxial injection. There is a black box warning against using Rivaroxaban and Apixaban with an indwelling epidural catheter. You can initiate treatment 6 hours after removing an epidural catheter.
Finally, we will cover antiplatelets. While aspirin has some effect on platelets, it is irrelevant to neuraxial anesthesia and does not alter timing for procedures or removal of catheters. Ticlodipine and Clopidogrel (Plavix) are platelet aggregation inhibitors, interfering with platelet-fibrinogen binding and ultimately platelet-platelet binding. These effects are irreversible for the life of the platelets. Ticlodipine must be held for 10 days prior to a neuraxial injection. After removing an epidural catheter, it can be restarted immediately. Clopidrogrel must be held for 5-7 days prior to a neuraxial injection. After an epidural catheter removal, it can be restarted immediately. Prasugrel is a new thienopyridine that inhibits platelets quicker and more efficiently than Clopidogrel. You should hold Prasugrel 7-10 days prior to a neuraxial injection. If can be restarted immediately after an epidural catheter is removed. Ticagrelor is a non-thienopyridine that reversibly inhibits ADP-induced platelet activation. You should hold it 5-7 days prior to a neuraxial injection. You can restart is immediately after an epidural catheter is removed.
