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ASRA Guidelines: Comprehensive Review for Anaesthesiology Consultants

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1. Background and Context

1. Anticoagulation and regional anesthesia (the most widely cited, with editions in 1998, 2003, 2010, 2018/4th edition, and 2022/2025 updates)
2. Local anesthetic systemic toxicity (LAST) prevention and treatment
3. Infection control in regional anesthesia
4. Ultrasound guidance and patient safety

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2. Fundamental Concepts: Why These Guidelines Exist

2.1 Risk of Spinal Epidural Hematoma (SEH)

• Incidence: approximately 1:150,000 epidurals and 1:220,000 spinal anesthetics in the general population
• In anticoagulated patients, incidence climbs dramatically
• SEH causes cord ischemia; outcomes depend on time to surgical decompression
• Neurological recovery is time-critical - laminectomy within 6-8 hours of symptom onset is the standard recommendation

• Anticoagulant or antiplatelet therapy
• Multiple attempts at needle placement / traumatic or bloody tap
• Indwelling epidural catheter during anticoagulation
• Female sex, older age
• Renal impairment (affects DOAC clearance)
• Anatomic abnormality of the spine

2.2 Procedure Risk Stratification

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3. Anticoagulants: Drug-by-Drug ASRA Recommendations

Sites of action of anticoagulant drugs:

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3.1 Warfarin (Vitamin K Antagonist)

• Stop warfarin 4-5 days before neuraxial procedure
• Confirm INR is normal (≤1.4 by ASRA; ≤1.4-1.5 by ESA) before proceeding
• If only a single dose of warfarin has been given, INR is typically normal and neuraxial block may be performed
• With an indwelling neuraxial catheter: check INR daily; remove catheter when INR ≤1.5
• When INR is 1.5-3.0, catheter can be maintained with caution; neurological monitoring mandatory
• When INR >3.0: hold or reduce warfarin; do not remove catheter until INR falls
• Restart: 12-24 hours post-procedure

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3.2 Unfractionated Heparin (UFH)

Subcutaneous Prophylactic UFH (5,000 units BID)

• No contraindication to neuraxial anesthesia
• Wait 4-6 hours from last dose before needle/catheter placement
• Catheter removal: 4-6 hours after last dose, 1 hour before next dose
• Administer first post-op dose no sooner than 1 hour after catheter removal

Subcutaneous Prophylactic UFH (TID - three times daily, >20,000 U/day)

• 2025 update: ASRA now recommends against neuraxial procedures in patients on a thrice-daily regimen pending further data (associated with spontaneous hematoma reports)
• If essential, assess coagulation status; recommend aPTT or anti-Xa monitoring

Intraoperative IV UFH (e.g., vascular surgery)

• Delay heparin at least 1 hour after needle/catheter placement
• Remove catheter 2-4 hours after last heparin dose, 1 hour before next dose
• Monitor aPTT or ACT
• Avoid neuraxial block in patients with pre-existing coagulopathy
• A traumatic/bloody tap: inform surgeon; consider delaying heparinization 24 hours

High-dose therapeutic UFH (>10,000 U SC per dose or >20,000 U/day)

• Neuraxial block 24 hours after last dose
• Assess coagulation status before proceeding (Grade 2C)

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3.3 Low Molecular Weight Heparin (LMWH)

• Anti-Xa level is NOT predictive of bleeding risk and should NOT be used to adjust timing
• Single-dose spinal anesthetic is the safest neuraxial technique in patients receiving perioperative LMWH
• Twice-daily LMWH in the presence of an indwelling epidural catheter is not recommended
• Postoperative LMWH administration should be delayed as long as possible (minimum 12 hours, ideally 24 hours after surgery)
• Assess platelet count if LMWH >4 days (HIT risk); hold LMWH if platelets <100,000

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3.4 Fondaparinux (Indirect Factor Xa Inhibitor)

• If neuraxial block is considered essential: wait ≥36-42 hours after last dose (2.5 mg OD)
• European guidelines: 36 hours pre-procedure, 6-12 hours post-procedure before restarting
• ASRA: if a neuraxial procedure is performed at day 5 post-fondaparinux, a platelet function test is recommended

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3.5 Direct Oral Anticoagulants (DOACs) - The Most Updated Section

Acceptable Laboratory Thresholds (NEW - 2025 ASRA):

• Residual DOAC level <30 ng/mL (calibrated drug-specific assay) OR
• Anti-Xa activity ≤0.1 IU/mL (for Xa inhibitors, calibrated to specific drug)
• For dabigatran: Thrombin time (TT) or dilute thrombin time (dTT) - PT/INR/aPTT are unreliable
• Reversal agents (andexanet alfa, idarucizumab, PCC) are NOT recommended for routine reversal prior to elective neuraxial procedures in the 2025 guidelines

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3.5.1 Rivaroxaban (Factor Xa Inhibitor, once daily)

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3.5.2 Apixaban (Factor Xa Inhibitor, twice daily)

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3.5.3 Edoxaban (Factor Xa Inhibitor)

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3.5.4 Dabigatran (Direct Thrombin Inhibitor)

• Catheter removal: 6 hours before first post-op dose
• Inadvertent dose with catheter in situ: wait 34-36 hours before catheter removal
• Monitoring: TT and dTT (NOT PT, INR, or aPTT - unreliable)

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3.6 Antiplatelet Agents

Aspirin and NSAIDs

• Alone: Do NOT increase risk of spinal hematoma in patients with normal coagulation
• Neuraxial block may proceed without interruption if the only antiplatelet agent
• The ASRA guidelines do not mandate discontinuation of aspirin for neuraxial procedures in patients without other coagulopathies

P2Y12 Receptor Antagonists

GP IIb/IIIa Inhibitors

• Abciximab: 24-48 hours (long recovery of platelet function)
• Eptifibatide / Tirofiban: 4-8 hours
• These agents are contraindicated with neuraxial procedures - if administered, neuraxial catheter management requires immediate consultation

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3.7 Fibrinolytic / Thrombolytic Therapy

• Neuraxial block should NOT be performed in patients receiving fibrinolytic or thrombolytic therapy (streptokinase, tPA) except in highly unusual circumstances
• No established safe interval between discontinuation and neuraxial technique
• If accidentally exposed: monitor fibrinogen levels; neurological monitoring every 2 hours
• If epidural catheter was in place when thrombolytics were given (European approach): leave in place until lytic effect fully resolved; use dilute local anesthetic infusion to facilitate neurological monitoring

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4. Summary Drug Timing Table

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5. Obstetric Patients - Special Considerations

• Low-dose prophylactic SC UFH (5,000 units BID): neuraxial block is acceptable; check for prolonged aPTT if >5 days of therapy
• Intermediate-dose UFH (e.g., 7,500-10,000 units BID): a 12-hour hold and normal aPTT before neuraxial block
• High-dose/therapeutic UFH (>10,000 U/dose or >20,000 U/day): 24-hour hold and documented normal aPTT
• Prophylactic LMWH: minimum 12 hours before neuraxial (same as general population)
• Therapeutic LMWH (twice-daily therapeutic dosing): 24 hours before neuraxial
• Decision trees (SOAP flowcharts) are incorporated into many obstetric anesthesia protocols globally

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6. Deep vs. Superficial Peripheral Nerve Blocks

• Deep, non-compressible blocks (lumbar plexus/psoas compartment, paravertebral, deep cervical plexus, celiac plexus): managed as if neuraxial - same time intervals apply
• Superficial/compressible blocks (interscalene, supraclavicular, axillary, TAP, femoral, popliteal): clinical discretion applies; lower risk but still requires individualized assessment
• The vascularity and compressibility of the anatomical site dictate risk more than the block name

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7. Local Anesthetic Systemic Toxicity (LAST) - ASRA Practice Advisory

7.1 Risk Factors for LAST

• Extremes of age (infants, elderly)
• Low lean body mass
• Pre-existing cardiac or liver disease
• High block site vascularity (intercostal > caudal > epidural > brachial plexus > sciatic/femoral)
• Intravenous injection (most common cause)

7.2 Clinical Presentation

• Early: metallic taste, circumoral numbness, tinnitus, lightheadedness, visual disturbance
• Moderate: muscle twitching, altered mental status
• Severe: seizures, loss of consciousness, coma

• Conduction delays (widened QRS)
• Ventricular dysrhythmias (VF is classic with bupivacaine)
• Cardiovascular collapse

7.3 ASRA LAST Treatment Algorithm (Step-by-Step)

• Call for help; note the time; don't leave the patient

• 100% oxygen; early intubation if needed
• Avoid hyperventilation (hypercarbia worsens toxicity; however, acidosis also worsens it - maintain normal pH)

• Benzodiazepines are first-line (midazolam, lorazepam)
• Avoid propofol in large doses (cardiac depressant; small doses acceptable)
• Succinylcholine for status epilepticus (to facilitate intubation, not an anticonvulsant)

• Epinephrine: limit to <1 mcg/kg (smaller than ACLS doses - to avoid triggering malignant arrhythmia)
• AVOID: vasopressin, calcium channel blockers, beta blockers, lidocaine for arrhythmias, other sodium/calcium channel blockers
• Amiodarone is acceptable for ventricular arrhythmias
• If refractory VF: initiate cardiopulmonary bypass preparations

• Timing: Start at the first sign of dysrhythmia - do not wait for cardiovascular collapse
• Mechanism: "lipid sink" hypothesis + direct cardiotonic effect
• Lipid emulsion works for all lipid-soluble local anesthetics (bupivacaine, ropivacaine, lidocaine)

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8. Infection Prevention in Regional Anesthesia - ASRA Practice Advisory

• Chlorhexidine in alcohol is the preferred skin antiseptic (superior to povidone-iodine)
• Allow chlorhexidine to fully dry before needle insertion
• Sterile gloves, mask, and aseptic technique for all neuraxial blocks
• Cap and sterile drape for all epidural catheter insertions
• Do not use multidose vials in the procedure area
• Epidural catheters: routine replacement at ≤5 days or per institutional protocol
• Tunnel epidural catheters when duration >3 days (reduces infection risk, especially via caudal route)
• Daily inspection of catheter insertion site
• Epidural abscess signs: back pain + fever + neurologic symptoms = MRI immediately

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9. Ultrasound-Guided Regional Anesthesia - ASRA Recommendations

Why ultrasound?

• Improves block success rate
• Decreases time to block onset
• Reduces minimum effective local anesthetic volume
• Reduces vascular puncture and hematoma formation
• Decreases LAST incidence

ASRA Statements on US-Guided Practice:

1. US does not eliminate the need for anticoagulation time intervals for deep blocks
2. US does lower bleeding risk enough to permit more liberal management of superficial/compressible blocks in anticoagulated patients
3. Training and competency standards must be maintained (societies mandate structured training curricula)
4. Nerve stimulation remains complementary for some deep blocks; US is primary

Safe US-Guided Regional Techniques:

• Aspiration before injection is mandatory - even with US, vascular puncture can occur
• Incremental injection with dose fractionation (3-5 mL aliquots with aspiration)
• Watch for injectate spread in real time - any resistance or lack of spread is a warning sign
• Avoid intraneural injection - "hydrodissection" appearance vs. nerve swelling

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10. Enhanced Recovery After Surgery (ERAS) and Regional Anesthesia

• Epidural analgesia: reduces ileus after colorectal surgery, decreases pulmonary complications after thoracic surgery, reduces DVT after joint arthroplasty
• Peripheral nerve blocks: reduced opioid consumption, earlier mobilization, reduced PONV
• Rebound pain after block offset: educate patients pre-operatively; bridge with multimodal analgesia (acetaminophen, NSAIDs, gabapentinoids, dexamethasone)
• Adjuvants to prolong nerve block duration:
  • Perineural dexamethasone (4-8 mg): extends duration by 6-8 hours, reduces rebound pain
  • Perineural dexmedetomidine: similar effect
  • Clonidine: mild extension, more hypotension risk
  • Liposomal bupivacaine (Exparel): up to 72 hours in some blocks

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11. Monitoring After Neuraxial Procedures

• Neurological checks every 2 hours minimum while epidural infusion is running
• Use dilute local anesthetic concentrations (0.0625%-0.125% bupivacaine) to preserve motor function and allow ongoing neurological assessment
• Any new back pain, lower extremity weakness, sensory loss, or bladder/bowel dysfunction after neuraxial block = immediate investigation for epidural hematoma
• MRI is the gold standard diagnostic tool
• If SEH suspected: urgent surgical consultation; decompressive laminectomy within 6-8 hours of onset for best neurological outcome

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12. Special Populations

Elderly Patients

• Renal function declines with age - DOAC hold intervals must be extended
• Anticoagulant peak levels may be higher and duration of action prolonged
• Assess CrCl using Cockcroft-Gault with actual (not ideal) body weight

Renal Impairment

• LMWH: use with caution if CrCl <30 mL/min; anti-Xa levels may be needed
• Dabigatran: contraindicated neuraxially if CrCl <30 mL/min
• Fondaparinux: avoid if CrCl <30 mL/min

Pediatric Patients (ASRA/ESRA Joint Advisory)

• Neuraxial and deep peripheral blocks are contraindicated if coagulation tests are abnormal
• LMWH: same half-life principles apply; timing adjusted to weight-based dosing
• Most pediatric blocks performed under general anesthesia (safe and accepted by large databases)
• LAST incidence in infants is higher (0.76:10,000 in PRAN registry) - caution with dosing
• Tunneled catheter preferred if caudal route used for >3 days

Patients with Pre-existing Neurological Disease

• Not an absolute contraindication to neuraxial anesthesia
• Document deficits thoroughly pre-operatively
• Informed consent discussion essential
• "Double-crush" vulnerability: an already-injured nerve may be more susceptible to further injury

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13. Key Concepts: ESA vs. ASRA Comparison (For Global Consultants)

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14. Decision-Making Framework for the Consulting Anaesthesiologist

1. Identify all anticoagulants and antiplatelet agents - including OTC NSAIDs, herbal supplements (fish oil, ginger, ginkgo, garlic - modest antiplatelet effects)
2. Classify the proposed block - high/intermediate/low hemorrhagic risk
3. Apply drug-specific ASRA hold intervals accounting for renal function and dose level (high vs. low)
4. Obtain relevant labs where indicated: INR (warfarin), aPTT or ACT (heparin), TT/dTT (dabigatran), calibrated anti-Xa (Xa inhibitors)
5. Consider the thrombotic risk of holding anticoagulation - consult with prescribing physician; bridge therapy if necessary
6. Document the risk-benefit discussion with the patient
7. Plan catheter management - schedule removal at appropriate intervals
8. Post-procedure monitoring - frequent neurological checks; low-concentration local anesthetic infusion

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15. Recent Updates (2022-2025)

1. Low-dose vs. high-dose DOAC distinction is now explicit - shorter intervals for prophylactic/low-dose regimens
2. Calibrated anti-Xa assay and residual DOAC level <30 ng/mL as laboratory "pass" thresholds allow earlier procedures when time intervals are not met
3. TT/dTT monitoring for dabigatran reinforced (not PT/INR/aPTT)
4. Reversal agents (andexanet alfa, idarucizumab, PCC) are NOT recommended for routine neuraxial procedures - insufficient safety data and risk-benefit unfavorable
5. UFH TID (thrice-daily) prophylaxis - recommendation against neuraxial procedures strengthened
6. Interventional spine pain procedures follow similar but slightly more conservative intervals (e.g., IV heparin restart 24 hours, not just 1 hour post high-risk procedure)
7. Ultrasound guidance recognized as a risk-mitigating tool specifically for superficial/compressible blocks in anticoagulated patients

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Summary: The 10 Non-Negotiable Rules from ASRA

1. Know your pharmacokinetics - every anticoagulant has a different half-life and clearance pathway
2. Adjust for renal function especially with DOACs and LMWH
3. Deep blocks = neuraxial rules - the compressibility principle governs risk
4. Do not remove catheters while drug is active - apply the same hold intervals to catheter removal as to insertion
5. LAST: start lipid emulsion early - at first dysrhythmia, not after cardiovascular collapse
6. Aspirin alone is not a contraindication - but combinations of antiplatelet + anticoagulant multiply risk
7. Warfarin needs documented normal INR - one dose of warfarin may be acceptable, ongoing therapy is not without INR confirmation
8. Thrombotic risk must be balanced against hemorrhagic risk - always consult with the prescribing physician before stopping anticoagulation
9. Neurological monitoring after neuraxial blocks is mandatory - especially in anticoagulated patients
10. Guidelines are living documents - check ASRA.com for the most current updates before high-risk decisions

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