The Daily Dose • Sunday, May 19

Avoiding the Hematoma: Updates for ASRA Regional and Pain Anticoagulation Guidelines

By Amanda Decimo, MSN, MPH, CRNA, from the IARS, AUA and SOCCA 2019 Annual Meetings*

The American Society of Regional Anesthesia and Pain Medicine (ASRA) regularly publishes guidelines to manage patients on anticoagulants for regional anesthesia and pain procedures. Dr. Honorio Benzon, MD, Northwestern University Feinberg School of Medicine, discussed recent changes in ASRA guidelines, why recommendations for regional and pain guidelines differ, reversal of novel oral anticoagulants (NOACs), and the CHADS2 scoring system.

A hot question in pain medicine today is “Maybe we shouldn’t stop anticoagulants when we do transforaminal epidural steroid injections (ESIs)?” However, the research suggests that hematomas do occur, and that we should.

Recent ASRA guidelines have attempted to align regional and pain guidelines, but this is not always possible. Why are there separate regional and pain guidelines? Pain procedures are more often treating elderly patients, patients with spinal stenosis, and scarring postlaminectomy patients. In general, these patients’ anatomy is less forgiving.

One study examined 9 patients with spinal hematoma following ESIs and spinal cord stimulator (SCS) implantation. All patients had normal coagulation studies and followed ASRA guidelines. This prompted the ASRA board to create separate pain anticoagulation guidelines.

Pain medicine guidelines are stratified for low, moderate, and high-risk procedures. Examples of low-risk pain procedures include: TPIs, peripheral nerve blocks, and joint injections. Moderate and high-risk procedures include: deep plexus blocks, epidural steroid injections, SCSs, and kyphoplasty.

For most anticoagulants, time of discontinuation is determined by Greenblatt’s Elimination Half-Life of Drugs study results. It concluded that after 2 half-lives 25% of a drug is remaining in the plasma, and after 5 half-lives, only 3% of the drug remains. This is adequate reversal.

Review of Anticoagulants:

Aspirin and Neuraxial Injections: 10-15% of circulating platelets are normal each day after discontinuation of ASA therapy. Four to five days after discontinuation, 50-60% of circulating platelets are unaffected by ASA.

Aspirin and NSAIDS: Regional guidelines are to continue therapy, and pain guidelines are the same for low-risk procedures. Moderate and high-risk procedures are more problematic: ASRA recommends discontinuing aspirin for 6 days in primary prophylaxis and 4 days for secondary prophylaxis.

Phosphodiesterase Inhibitors: Regional guidelines recommend continuing therapy. Pain recommends discontinuing for 2 days (five half-lives).

P2Y12 Inhibitors: Inhibit platelet aggregation (clopidogrel, prasugrel and ticagrelor). Regional and pain guidelines are the same for discontinuation of these drugs. However, each drug differs slightly. They are safe to resume in 12-24 hours; it takes several days for P2Y12 inhibitors to reach peak effect. However, do not resume with a loading dose or peak effect will occur too quickly.

When clopidogrel is stopped for only 5 days platelet function testing is indicated, otherwise hold for 7 days. The P2y12 assay reflects similar results when clopidogrel is stopped for 5 days versus 7 days (it indicates less than 10% inhibition). A word of caution, there have been case reports of MI 6-7 days after clopidogrel was stopped.

Warfarin: There are 2 different scenarios for INR monitoring: patients not on coumadin INR ≤ 1.4 and patients on coumadin INR ≤ 1.2 (after stopping coumadin for 5 days). This is especially important for medium and high-risk pain procedure.

It’s important to consider that many issues outside of lab values play a part in the development of a hematoma.

IV Heparin: Regional and pain guidelines are the same. When resuming IV heparin after spinal or epidural wait 1-2 hours. The half-life depends on the dose; this becomes clinically relevant for high doses used in cardiac surgery.

Subcutaneous (SQ) Heparin:
(I) BID SQ heparin regional guidelines vary based on dose. Pain guidelines vary according to risk stratification of the procedure.
(II) TID SQ heparin dosing is a new practice; previously regional and pain guidelines were not to perform the procedure. However, recent studies indicate that we can safely perform spinals and epidurals in patients on TID SQ heparin. Although for pain, the recommendations are to avoid, if possible, with medium and high-risk procedures. Be aware that surgeons are not likely going back to BID dosing, as it’s less effective.

Low Molecular Weight Heparin (LMWH): Regional and pain guidelines are the same. Caution with obese patients on higher doses. Time of discontinuation is dose-dependent.

Fondaparinux is a factor Xa inhibitor with a long half-life (17-21h). Regional has no recommendations. Pain recommends discontinuation for 5 half-lives (4 days).

Fibrinolytic Agents have new regional and pain guidelines. These drugs have short half-lives (3-4 hours), but the recommendation is to discontinue for 48 hours. Ideally, avoid this scenario and wait 72 hours.

Novel Oral Anticoagulants (NOACs): No studies on NOACs are currently available, so guidelines are based purely on pharmacokinetics. ASRA decided to use 5 half-lives to determine when NOACs are discontinued because only 3% of the drug will remain in the plasma.

It takes 8 hours for stable clot formation. Resumption of NOACs is based on this observation. Regional recommendations are to resume after 6 hours and pain recommendations are to resume after 6 hours for low-risk procedures and 24 hours for high-risk procedures.

Since dabigatran has significant renal clearance, discontinuation varies according to creatinine clearance for both regional and pain guidelines.

Lab monitoring for dabigatran is PTT, but the relationship is not linear. Monitoring for Factor Xa inhibitors (rivaroxaban and apixaban) with factor Xa assays, which is not available in most hospitals.

NOAC Reversals
(1) Idarucizumab is a monoclonal antibody fragment that binds to dabigatran. The effect is seen within minutes.
(2) Andexanet is a protein that binds to Factor Xa inhibitors (rivaroxaban and apixaban).

Herbal Medications: Regional guidelines are to continue. Pain guidelines for moderate and high-risk procedures:

  • garlic (high dose of 2000mg/day) discontinue for 7 days
  • ginkgo biloba: check platelets
  • dong quai (potentiates warfarin): INR
  • danshen (warfarin elimination): INR

Antidepressants: Only SSRIs need consideration, as their antiplatelet effect is the same as ibuprofen. Regional guidelines are to continue, and pain recommends discontinue for 1-2 weeks, except for fluoxetine (discontinue 5 weeks).

CHADS2 scoring was developed to assess the risk of developing an MI or CVA from venous thromboembolism when anticoagulants are discontinued for a procedure. CHADS2 score of 2 increases the stroke rate by a factor of 4; CHADS2 score of 3 increases the stroke rate by a factor of 6. Talk to patients about that risk with CHADS2 scores of 3, and consider LMWH bridge therapy so that they are covered.

During the Q and A session, Dr. Benson emphasized that while these guidelines are important, individual patient and procedural factors should be considered. Laboratory values and adherence to ASRA guidelines are not the only relevant factors to consider for preventing hematomas.

*Coverage from RCL: The ASRA Regional and Pain Anticoagulation Guidelines during the IARS 2019 Annual Meeting