Keywords: Peripheral nerve blocks for total hip arthroplasty; common anticoagulation medications; anticoagulation in regional anesthesia

Transcription

1 64 th Annual Postgraduate Symposium on Anesthesiology Department of Anesthesiology Kansas University Medical Center Problem Based Learning Discussion Does Anti coagulation Mean Anti regional??? Contact Information: Gina Hendren, MD Assistant Professor, Program Director Neesha Dhanak, DO Regional Anesthesia Fellow Keywords: Peripheral nerve blocks for total hip arthroplasty; common anticoagulation medications; anticoagulation in regional anesthesia Learning Objective #1: Upon completion of this learning activity, participants should be able to describe common blocks for total hip arthroplasty Learning Objective #2: Upon completion of this learning activity, participants should be able to discuss the American Society of Regional Anesthesia (ASRA) guidelines for common anticoagulation regimens Learning Objective #3: Upon completion of this learning activity, participants should be able to recognize and describe the signs, symptoms and treatment of local anesthetic systemic toxicity (LAST) Learning Objective #4: Upon completion of this learning activity, participants should be able to comprehend the mechanism of action of newer anticoagulation regimens Case scenario #1: A 78 year old 90 kg male with a past medical history significant for hypertension and atrial fibrillation on Coumadin, presents for a left total hip arthroplasty. Preoperative labs reveal an INR 2.5. What are this patient s co morbidities that we should take into consideration when creating an anesthetic plan for him? o HTN, atrial fibrillation on Coumadin, age, weight, INR. Keep in mind not every patient with atrial fibrillation needs to be anticoagulated (10%: ALLHAT weigh risk vs benefit) What are the anesthetic options for this patient? What do you do at your institution? o Consider general anesthetic, peripheral nerve block, neuraxial block.

2 What would be the benefit of using regional anesthesia in this case for post operative analgesia? o Can improve patient outcomes reduce pain after surgery, less nausea, provide better pain control than systemic narcotics, easier breathing resulting from better pain control, easier participation in physical therapy, overall improved patient satisfaction Can we do a peripheral nerve block on this patient? If so, what are the options? Why would we choose one over the other(s)? Who would perform this block? (see exhibit A) o Possible regional anesthesia for total hip arthroplasty include neuraxial techniques such as an epidural or spinal, and peripheral nerve blocks such as a lumbar plexus (psoas) block or fascia iliaca compartment block. o Lumbar plexus Block Injection of local anesthetic most commonly results in anesthesia of lumbar nerve roots (T12 L4). Nerves included in this block are: femoral n, LFCN, obturator n, iliohypogastric n, ilioinguinal n, genitofemoral n Patient is in the lateral decubitus position with a slight forward tilt. Foot on the side of the block is positioned over the depended leg so twitches of quadriceps/patella can be appreciated. Landmarks: Midline (L4); iliac crest, needle insertion 4 cm lateral to intersection of midline and iliac crest. This block is commonly performed using nerve stimulator. Hematoma is a real concern when performing this block. These blocks are best avoided in patients receiving anticoagulant therapy (same considerations as for the use of neuraxial anesthesia in patients on anticoagulant therapy) o Fascia iliaca Injection of local anesthetic most commonly results in anesthesia of the three major nerves of the lumbar plexus: femoral, obturator, & LFCM Patient is supine Landmarks: ASIS, pubic tubercle. A line is drawn between these two landmarks and the line is dissected into thirds. Needle insertion is 1.5 2cm caudad from lateral third. This block has been described using ultrasound, nerve stimulator or doing a field block technique. In what setting would you perform the peripheral nerve block? Why? At your institution do you have a designated block area? o Consider pre op/post op area, OR, ER a location easily accessible to airway equipment and emergency medications. Perform block in a designated area with

3 proper equipment and monitoring devices. All supplies, drugs and equipment must be readily available. The designated area should be larger enough and have proper lighting, suction, and equipment for oxygen administration and emergency airway management, including positive pressure ventilation. o What monitors are needed for this block? Why? Performance of regional anesthesia techniques requires proper set up, careful preparation, detailed planning, and continuous monitoring for safe and effective patient care. Monitors should be used similar to a patient undergoing general anesthesia (ASA monitors). Level of consciousness, pulse oximetry, vital signs including BP, HR, EKG, and RR should be monitored and documented throughout the procedure. o What kinds of volumes are appropriate when placing a peripheral nerve block? o If the patient develops suspected local anesthetic systemic toxicity (LAST) from the block (ex: while injecting, the patient becomes agitated), what are your next steps? (see exhibit B) What are the signs/symptoms of LAST? What is the treatment of LAST? Does it matter whether one uses ropivacaine or bupivacaine? o Signs and symptoms of local anesthetic systemic toxicity include CNS and cardiac effects CNS signs: excitation/seizure, depression/apnea, metallic taste, circumoral numbness, diplopia, tinnitus, dizziness Cardiovascular signs: initial hyperdynamic state, progressive hypotension, conduction block, bradycardia, asystole, ventricular arrhythmia o Immediate next steps if LAST is suspected: call for help, focus on airway, seizure suppression and alert nearest cardiopulmonary bypass facility of the situation. Start ACLS measurements but remember prolonged effort may be required. Reduce doses of epinephrine and avoid vasopressin, CCBs, beta blockers. Avoid propofol.

4 o Treatment: Intralipid 20% therapy bolus and infusion to avoid refractory events. See checklist for details. o Risk reduction: establish the toxic LA dose prior to each procedure. Use the least dose necessary to achieve desired block. Consider co morbidities of the patient as well as site of injection. Use a pharmacologic marker/test dose. Aspirate the syringe prior to each injection and inject incrementally. Be vigilant. o In dogs, supraconvulsant doses of bupivacaine more commonly produce arrhythmias than supraconvulsant doses of ropivacaine. Bupivacaine binds more avidly and longer than lidocaine to cardiac Na channels which led to development of ropivacaine. Rank order for cardiac toxicity in rats appears to be bupivacaine > levobupivacaine > ropivacaine. If we place a peripheral nerve block, can we place a catheter? o While data is limited in regards to studies on peripheral nerve blocks in the presence of anticoagulants, one should realize that spontaneous hematomas in various locations have been reported in patients on anticoagulation. Cases of retroperitoneal hematoma after lumbar plexus block have been reported. While it may be restrictive (Hadzic) to adapt the same ASRA guidelines on neuraxial blocks to patients undergoing peripheral nerve blocks, one should use clinical judgment when performing the lumbar plexus block. In this case, the fascia iliaca block would be most appropriate. o If so, when do we place it and when do we remove it? At our institution a fascia iliaca catheter could be placed in this patient. Because of surgical prepping and the nature of the case itself, a single injection fascia iliaca block may be placed pre operatively. In the PACU, a catheter can then be placed for post operative pain control. At our institution, we remove the catheter on POD#2 (per surgeon request; this is the pathway that our institution has developed). o Do we need to time it with this patient s anticoagulation regimen? Per ASRA guidelines, for patients undergoing deep plexus or peripheral block, we recommend that recommendations regarding neuraxial techniques be similarly applied. At our institution, the fascia iliaca catheter could be placed with an INR of 2.5, whether or not the patient has been off Coumadin for the recommended 5 7 days. Removing the catheter does not need to be timed with the patient s anticoagulation when doing a fascia iliaca block as this anatomy lends itself to an easily compressible area if hematoma were to occur. Do we to administer any reversal prior to the nerve block given his current INR?

5 o For peripheral nerve block purposes only, a fascia iliaca block could proceed without reversal of this patient s anticoagulation. This is not a deep peripheral/deep plexus block, and the block is relatively minor to perform. According to the ASRA Guidelines (Third Edition), during warfarin therapy, an INR of 2.0 to 3.0 is associated with a low risk of bleeding: less than 3% during a 3 month treatment period. o For completeness sake, reversal options include: Vitamin K, fresh frozen plasma, prothrombin complex concentrates, and factor VIIa Instead of an elective total hip arthroplasty, suppose this same patient had fallen and suffered a hip fracture one week ago. He has been followed in the hospital by the internal medicine team who bridged his anticoagulation with low molecular weight heparin for the last week, and now the family has agreed to have the patient s hip surgically corrected. He was started on a fluoroquinolone antibiotic. His most recent INR is 5.0. o What are the ASRA guidelines for this patient? (see exhibit C(a d)) While long term anticoagulation with warfarin is often indicated in patients with atrial fibrillation, when these patients present for elective or urgent procedures, perioperative management is a balancing act between the risks of surgical bleeding and thromboembolism. Bridging therapy to minimize the risk of thromboembolism is necessary in this patient. Low molecular weight heparin (LMWH) is required in this patient until the time of surgery and should be reinitiated in the immediate postoperative period. The doses of LMWH for bridge therapy are associated with DVT treatment, not prophylaxis, and are much higher. It is important to note that for a neuraxial blockade, needle placement in these patients should occur a minimum of 24 hours after the last dose. It is also important to determine when the first postoperative dose is to be given. When applying these guidelines to deep plexus block, it is best to avoid lumbar plexus peripheral nerve block and still be vigilant when placing a fascia iliaca block and catheter. o Does the INR of 5.0 change your decision of whether or not to give this patient a peripheral nerve block? If we did place a peripheral nerve block, which one? Would we place a catheter? According to the ASRA guidelines, how do we time this block placement with the patient s anticoagulation? This patient was bridged with lovenox but unfortunately his INR is still supratherapeutic, perhaps from antibiotic use. According to the ASRA guidelines (third edition), while spinal hematoma is the most significant

6 hemorrhagic complication of regional anesthesia secondary to bleeding in a noncompressible, fixed space, the associated risk after plexus and peripheral techniques remains undefined. There are few reports of serious complications. While there are case reports of bleeding into a neurovascular sheath with significant decreases in hematocrit, published cases of patients with neurodeficits recover within 6 to 12 months, suggesting the expandable nature of peripheral sites may decrease the chance of irreversible neural ischemia. The ASRA practice advisory recommends the same recommendations regarding neuraxial techniques be applied to deep plexus or peripheral blocks. Clinical judgment in this case is imperative. We recommend forgoing a peripheral nerve block in this patient. If a peripheral nerve block was chosen, a single injection might be the best choice, so as not to worry about removing the catheter around the timing of this patient s anticoagulation. INR > 4 is associated with increased risk of hemorrhage, including intracranial hemorrhage. On POD #2 he develops acute kidney injury. His pain is controlled with the PNC you placed pre operatively. He is on LMWH. His latest INR is 6.0. What are your plans to remove the PNC? o According to the newest update from ASRA in November 2013, for LMWH, placement or removal of a neuraxial catheter should be delayed for at least 12 hours after administration of a prophylactic dose; however longer delays (24 hours) are appropriate to consider for patients receiving higher therapeutic doses. This information should be taken into consideration when applying to peripheral nerve blockade and benefit risk assessment should consider both the risk for thrombosis by delaying anticoagulation and the risk for bleeding. Case scenario #2: A 78 year old 90 kg male with a past medical history of hypertension and significant obstructive sleep apnea with use of a CPAP, presents to the pre operative area after falling yesterday. He suffered a right hip fracture that will need to go to the OR for surgical correction. Upon admission to the hospital last night, he was diagnosed with new onset atrial fibrillation. In addition to a diltiazem drip, the cardiology team placed him on a heparin drip as well. His most recent PTT is 70. Can we do a peripheral nerve block on this patient? If so, which one?

7 o Again, the best choice for peripheral nerve blockade in this patient would be the fascia iliaca, as discussed above. o This patient would benefit from regional anesthesia given his significant sleep apnea. One must weigh the risk benefit ratio of performing a superficial peripheral nerve block at a compressible site in an anticoagulated patient and the obvious threat that narcotic medication could pose to someone with an already sensitive central state and potentially difficult airway. If we place a peripheral nerve block, can we place a catheter? If so, when do we place it and when do we remove it? Do we need to time it with this patient s anticoagulation regimen? o Given the nature and urgency of this procedure, there is little room for timing the block with the patient s anticoagulation regimen. Because the fascia iliaca block warrants a single injection preoperatively, a catheter may be placed in the postoperative state only if the patient shows he needs it. Avoiding another procedure might be ideal with an actively anticoagulated picture; on the other hand, one must understand that regional anesthesia might be this patient s best form of pain control to avoid heavy narcotics given his co morbidities. Do we to administer any reversal prior to the nerve block given his current PTT? o We would suggest discussing this patient s regimen with the cardiology and surgical teams. However, anticipating a procedure with a fair amount of blood loss in an already tumultuous patient, reversal may be appropriate in order to proceed with the surgery. For purposes of the peripheral nerve block only, if one were to perform a fascia iliaca block, reversal would not be necessary in this case. What if this patient were placed on Arixtra (fondaparinux) post operatively? o Fondaparinux produces its antithrombotic effect through factor Xa inhibition. The plasma half life is 21 hours. The prophylactic dose for fondaparinux is 2.5 mg SQ administered 6 hours postoperatively. The therapeutic dose is 5 mg SQ. o A recent study of 1631 patients undergoing continuous neuraxial or deep peripheral block receiving fondaparinux reported no serious hemorrhagic complications. However, the catheters were removed 36 hours after the last dose and subsequent dosing was delayed for 12 hours after removal. o Most recent guidelines suggest that the neuraxial or deep plexus block be delayed for hours for prophylaxis treatment and if the patient is receiving (or going to be receiving) a therapeutic dose of fondaparinux (5 mg), then avoid neuraxial or deep plexus block altogether. Our experience would be to avoid lumbar plexus block in this case.

8 o According to the European Society of Anesthesia (ESA), if a catheter is to be maintained while a patient is on fondaparinux, removal should be hours from the last dose. o What if he were placed on Eliquis (apixaban)? Pradaxa (dabigatran)? Xarelto (rivaroxaban)? (see newest updates handout) See handout for latest recommendations about these drugs. o What kinds of monitoring would we need for each of these medications? These drugs in most patients do not require routine monitoring. If they do need monitoring the following can be drawn (but may not be available at your institution s laboratory): Fondaparinux, apixaban, rivaroxaban (Xa inhibitors) anti Xa assay o aptt and PT (not INR) may be prolonged but not reliable Dabigatran diluted TT/ECT o aptt and ACT may be prolonged but not reliable; PT/INR to unreliable o How does each of these medications work? What pathways do they work on? (see exhibit D) Indirect Factor Xa inhibitors: fondaparinux Direct Factor Xa inhibitors: apixaban, rivaroxaban Direct thrombin inhibitor: dabigatran o How does that affect our decision to perform a peripheral nerve block? Understanding the patient s co morbidities, pain control requirements and the mechanisms and half lives of these medications is essential. Sound clinical judgment in performing these blocks in the chronically anticoagulated patient is best. We recommend adhering to ASRA guidelines when hesitations arise. EXHIBIT KEY Exhibit A: Anatomy of peripheral nerve blocks for total hip arthroplasty Exhibit B: Checklist for treatment of local anesthetic systemic toxicity Exhibit C(a d): American Society of Regional Anesthesia Practice Advisory (adapted, abbreviated version) Exhibit D: Coagulation cascade and anticoagulation medications

9 References: Barta, B., Wild, D. Reversal Strategies for the Chronically Anticoagulated: A Review and the New. Kansas University Medical Center Department of Anesthesiology Grand Rounds. February 25 th, Hadzic, A. Textbook of Regional Anesthesia and Acute Pain Management. The McGraw Hill Companies, Inc Horlocker, et al. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy. American Society of Regional Anesthesia and Pain Medicine Evidence Based Guidelines. 3 rd ed. Reg Anesth Pain Med 2010;35:64 101) th Annual American Society of Regional Anesthesia Meeting. Chicago, IL. April 3 6, 2014.