EMCrit Here. Welcome to a new segment here on the ‘Crit–Confounding Questions in Resus (CQiR pronounced Seek-Here). The EMCrit assistant editor who will be handling this new section is Stony Brook's own, Ashley Mogul. Ash is our academic chief resident and nascent super-star. On an intermittent basis, she will take questions from the EMCrit audience, her clinical practice, or mine that have given us pause and then try to find an expert who can answer them. The idea is that these are questions that a simple lit search will not answer, but instead ones that rely on best clinical practice.
We have a great one to start off the series: can you perform an LP on patients on anti-platelet agents. To find the answer, Ashley sought out EMCrit's own Laura Duggan. Let's get to it:
To tap or not to tap?
by Ashley Mogul
I chatted with Dr. Laura Duggan, anesthesiologist and friend of EMCrit regarding whether it is safe to perform lumbar punctures (LP) in patients on aspirin, plavix, or both.
She had some surprisingly clear answers:
Plavix- No way! She cites waiting 5 days, though the range of platelet inhibition may be 3-10 days depending on metabolism.
Evidence from the anesthesia literature can be used to extrapolate to the emergency medicine and resuscitation world. It seems that a spinal anesthesia procedure without the placement of an indwelling catheter is most similar to a lumbar puncture procedure. This procedure carries an intermediate risk of bleeding per the American Society of Regional Anesthesia and Pain Medicine (ASRA)1.
Laura directed me to guidelines from the ASRA, most recently published in April 20181, regarding the performance of spinal procedures in patients on antiplatelet and anticoagulants.
In regards to aspirin, both the American and European regional societies recommend performing central neuraxial blocks on patients on this drug without medication discontinuation. The indication for aspirin is also important when considering risk and benefits: if the luxury of time was available you may consider stopping the drug for about 6 days if the indication for aspirin was primary prophylaxis, but if prophylaxis is secondary, the cardiovascular risk is higher if the medication is ceased. You may also consider the potentiation of aspirin’s effect by other drugs such as selective serotonin reuptake inhibitors and alcohol. To avoid or delay LP would be very conservative and is likely not necessary for this procedure.
For plavix, stopping for 7 days before the procedure or 5 days before followed by a platelet function test showing adequate function seems like a hard stop. This is especially true in patients more likely to bleed such as those who are older or those with comorbid liver or renal disease.
If you are able to obtain an aspirin or plavix response, this may aid in deciding whether to go forward with the procedure, especially for a patient who cannot give a history or may be noncompliant on their medication.
What about giving platelets to reverse the medication if LP is considered in the acute setting? For plavix especially, would this allow us to skip the 7 day wait and LP? One would have to weigh the risks and benefits and consider the exposure involved, especially in instances where multiple pooled donor units are used. The question of how many units would be needed and whether this would truly correct the hemostatic abnormality remain. Increased thrombotic risk in setting of antiplatelet reversal should also be considered. It is unlikely that necessity for this procedure is justified for patients on plavix considering the paucity of evidence.
As most serious post-procedure bleeding in general is due to local trauma, even in patients with normal clotting, Laura mentions the needle type as another important factor to consider. Blunt tip needles such as the Witacre create less tissue trauma and are associated with less post LP headaches; Laura postulates that it may also be associated with less bleeding. As this is often not the type of needle that we are trained with, consider spending some time in Sim lab or with anesthesia colleagues to get used to the subtle variation in motor skills necessary.
A literature search regarding lumbar puncture and antiplatelets revealed two pertinent recent articles. The Mayo clinic2 recently published a retrospective chart review of 100 patients on aspirin and plavix who underwent LP, finding that no major adverse bleeding events occurred. The rates of both traumatic and bloody LPs in this study were less than the estimated incidence in the general population of about 10% for bedside studies. It should be noted that about three quarters of procedures were performed by dedicated LP nurses in the outpatient setting who likely have experience with this procedure that greatly exceeds that of most emergency medicine providers or intensivists. The second article3 is a review that attempts to make recommendations based on current evidence. Unfortunately, for patients on aspirin, this evidence is extrapolated from anesthesia literature and not based on patients actually undergoing LP so does not further knowledge on the topic. For patients on plavix, this article notes a low bleeding risk and recommends performing the LP but the evidence for which they draw this conclusion is unclear.
The guidelines that exist within anesthesia literature are based on limited data, both on clinical and animal models, and are not meant to represent standard of care or replace clinical judgement. They are rather meant as conservative recommendations to decrease risk and allow for optimal patient care though cannot guarantee avoidance of adverse events. Be sure to consent your patient appropriately, proceed with appropriate care, and monitor afterwards for any neurologic sequelae. There may also be a role for fluoroscopy-guided procedure in this situation due to decreased incidence of bleeding in the general population. But it seems safe to say LP your patient on aspirin but think twice about your patient on plavix.
- Narouze S, Benzon HT, Provenzano D, et al. Interventional spine and pain procedures in patients on antiplatelet and anticoagulant medications (second edition). Regional Anesthesia and Pain Medicine; 2018; 43(3): 225-262.
- Carabenciov ID, Hawkes MA, Hocker S. Safety of lumbar puncture performed on dual antiplatelet therapy. Mayo Clin Proc; 2018: 1-3.
- Domingues R, Bruniera G, Brunale F, Mangueira C, Senne C. Lumbar puncture in patients using anticoagulants and antiplatelet agents. Arq Neuropsiquiatr; 2016; 74(8): 679-686.