Recommended Approach for Administering Deep Nerve Blocks for Surgical Procedures
For deep nerve blocks such as femoral nerve (FN) or sciatic nerve (SN) blocks, ultrasound guidance is strongly recommended to ensure precise placement, visualize vascular structures, and enhance safety while reducing the risk of complications.
Classification of Nerve Blocks by Bleeding Risk
Nerve blocks can be categorized based on bleeding risk, which guides their administration in different clinical scenarios:
Low Bleeding Risk Blocks
- Definition: Blocks where bleeding is easily controllable and the area can be compressed
- Examples: Femoral nerve block, axillary plexus block, popliteal sciatic nerve block
- Antiplatelet Considerations:
- Can be performed in patients on mono or dual antiplatelet therapy if benefit/risk ratio is favorable 1
- Safe to perform with aspirin therapy
High Bleeding Risk Blocks
- Definition: Blocks where bleeding cannot be compressed or has potentially serious consequences
- Examples: Infraclavicular brachial block, para-sacral sciatic block, posterior lumbar plexus block
- Antiplatelet Considerations:
- Can be performed in patients on aspirin monotherapy if benefit/risk ratio is favorable
- Contraindicated in patients on P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) unless discontinued 5-7 days before procedure 1
Technical Considerations for Deep Nerve Blocks
Equipment and Positioning
- Position ultrasound equipment directly in front of the operator
- Use dominant hand for needle insertion, especially for novice operators 2
- Avoid rotating trunk or head more than 45° to prevent fatigue and suboptimal block performance
Procedural Technique
- In-plane technique is recommended for beginners to visualize the entire needle trajectory 2
- Use fractional (incremental) doses rather than rapid injection of large volumes 3
- For brachial plexus blocks, supraclavicular approach shows consistently higher success rates (92%) compared to axillary approach (56-86%) 3
Medication Selection and Dosing
- For femoral nerve blocks: Use ropivacaine 0.5% (175-250 mg) or 0.75% (75-300 mg) 3
- For sciatic nerve blocks: Similar dosing as femoral blocks, with onset time of 10-25 minutes and duration of 6-10 hours 3
- For posterior lumbar plexus blocks: Greater efficacy than femoral nerve blocks in total hip replacement but higher risk of complications 1
Neuromuscular Blockade Considerations
Depth of Blockade
- Deep neuromuscular blockade improves surgical conditions in laparoscopic procedures 1, 4
- Monitoring of neuromuscular blockade intraoperatively is strongly recommended 1
- Deep blockade allows for lower pneumoperitoneum pressures in laparoscopic surgery (9 mmHg vs 12 mmHg) 1
Monitoring Requirements
- Quantitative monitoring of the adductor pollicis is recommended to diagnose residual neuromuscular blockade 1
- Target a T4/T1 ratio of 0.9 at the adductor pollicis to eliminate residual blockade 1
Clinical Applications and Outcomes
For Lower Extremity Surgery
- Posterior lumbar plexus blocks have greater efficacy than femoral nerve blocks for total hip replacement 1
- Combined femoral and sciatic nerve blocks with sedoanalgesia can be an alternative to spinal anesthesia in selected patients 5
- For medial open wedge high tibial osteotomy, both femoral and sciatic nerve blocks provide similar analgesia in the setting of multimodal pain management 6
For Patients with Respiratory Concerns
- Peripheral nerve blocks are particularly valuable in patients with restrictive ventilatory impairment 7
- Femoral and sciatic nerve blocks allow for spontaneous ventilation during surgery, reducing respiratory complications
Post-Procedure Management
- Inform patients about expected duration of block and provide written instructions for post-block care 2
- Initiate oral analgesics before the effect of local anesthetic begins to wear off 2
- For continuous infusions, ropivacaine 0.2% at 6-14 mL/h (12-28 mg/h) is effective for postoperative pain management 3
Common Pitfalls and Caveats
- Failure to use ultrasound guidance increases risk of vascular puncture and hematoma formation
- Inadequate monitoring of neuromuscular blockade can lead to residual paralysis
- Performing high bleeding risk blocks in anticoagulated patients increases complication risk
- Not accounting for individual anatomical variations can lead to block failure
Deep nerve blocks, when performed with proper technique and monitoring, provide excellent surgical conditions and postoperative analgesia while potentially reducing respiratory complications compared to general anesthesia.