Nerve Blocks Guideline

Introduction to Nerve Blocks

• Nerve blocks can be classified into two main categories based on bleeding risk: low bleeding risk peripheral blocks and high bleeding risk blocks, with each type having specific indications and contraindications depending on patient anticoagulation status 1

Classification of Nerve Blocks

• Low bleeding risk peripheral blocks include superficial blocks such as femoral nerve block, axillary plexus block, and popliteal sciatic nerve block, which can be performed in patients on antiplatelet therapy if the benefit/risk ratio is favorable 1
• High bleeding risk blocks include deep blocks such as infraclavicular brachial block, para-sacral sciatic block, and posterior lumbar plexus block, which are contraindicated in patients on P2Y12 inhibitors unless discontinued 5-7 days before the procedure 1

Central Neuraxial Blocks

• Central neuraxial blocks, including spinal anesthesia and epidural anesthesia/analgesia, are contraindicated in patients on P2Y12 inhibitors, but aspirin is not a contraindication if the benefit-risk ratio is favorable 1

Specific Nerve Blocks

• Brachial plexus blocks, including interscalene, supraclavicular, infraclavicular, and axillary blocks, have varying levels of risk and should be performed with caution 1, 2
• Lumbar plexus block and sciatic nerve block (parasacral approach) are considered high bleeding risk blocks, while femoral nerve block and sciatic nerve block (popliteal approach) are considered low bleeding risk blocks 1
• Adductor canal block is a newer approach with less quadriceps weakness 1
• Posterior lumbar plexus blocks have greater efficacy than femoral nerve blocks for total hip replacement, according to the American Society of Anesthesiologists guidelines 3

Other Nerve Blocks

• Transversus abdominis plane (TAP) block, erector spinae plane block, quadratus lumborum block, and intercostal nerve blocks are other types of nerve blocks that can be used for various surgical procedures 2

Technique and Safety

• Ultrasound guidance is recommended for precise placement of local anesthetic, reduction of total dose administered, and increased safety by visualizing vascular structures 1, 4, 5
• Test dose is recommended before full administration to detect intravascular injection, and blocks should be performed by experienced operators, especially high-risk blocks 1
• Optimal block performance requires minimal trunk or head rotation (<45°), and the use of the dominant hand for needle insertion, especially for novice operators, with the position of the ultrasound equipment in front of the operator improving accuracy 5
• A dedicated block room can improve efficiency and allow for confirmation of adequate nerve block before surgery begins, with patients informed of the expected duration of the block and provided with written instructions on how to behave until normal sensation and strength return 4

Risks and Complications

• Common risks for all nerve blocks include vascular puncture and bleeding, nerve damage, and local anesthetic systemic toxicity 1
• Block-specific risks, such as quadriceps weakness with femoral nerve blocks and respiratory compromise with interscalene blocks, should be considered when selecting a nerve block 1
• Patients on anticoagulation therapy should be aware of the increased risk of hematoma with peripheral blocks 6, 7

Performance Time and Recommended Technique

7, 4, 5

Monitoring and Postoperative Care

• Quantitative monitoring of the adductor pollicis is recommended to diagnose residual neuromuscular blockade, with a target T4/T1 ratio of 0.9 to eliminate residual blockade 8
• Oral analgesics should be initiated before the effect of the local anesthetic begins to wear off 6, 7
• The American Society of Anesthesiologists recommends proper technique and monitoring for nerve blocks to provide excellent surgical conditions and postoperative analgesia, potentially reducing respiratory complications compared to general anesthesia 1