Why combine peripheral nerve blocks (PNB) and general endotracheal intubation (GETI) for surgical procedures?

Why Combine Peripheral Nerve Blocks with General Endotracheal Intubation

Combining peripheral nerve blocks (PNB) with general endotracheal intubation (GETI) provides superior postoperative analgesia, reduces opioid requirements, improves hemodynamic stability, and decreases respiratory complications while maintaining a secure airway for procedures that require it.

Primary Rationale: Optimizing Analgesia While Securing the Airway

When General Anesthesia with Secure Airway is Mandatory

General anesthesia with a secure airway is preferable to deep sedation without a secure airway, particularly for procedures that may mechanically compromise the airway 1. This includes:

• Procedures involving the thorax or abdomen where surgical manipulation could obstruct breathing 1
• Patients at increased perioperative risk from obstructive sleep apnea (OSA) where airway protection is critical 1
• Operations requiring complete immobility or specific positioning that precludes patient cooperation 1

Why Add Peripheral Nerve Blocks to General Anesthesia

Regional analgesic techniques reduce the likelihood of adverse outcomes compared to systemic opioids alone 1. The combination provides several critical advantages:

Opioid-Sparing Effects

• Peripheral nerve blocks significantly reduce intraoperative and postoperative opioid requirements 1, 2
• Lower opioid consumption decreases respiratory depression risk, particularly important in OSA patients 1
• Reduced opioid use minimizes postoperative nausea, vomiting, and sedation 1

Hemodynamic Stability

• Peripheral nerve blocks provide anesthetic sparing effects, reducing volatile anesthetic and opioid requirements during surgery 2
• Heart rate and mean arterial pressure remain more stable when regional blocks supplement general anesthesia 2
• Unlike neuraxial blocks, peripheral nerve blocks do not cause sympathectomy or widespread hemodynamic effects 3

Superior Postoperative Pain Control

• Continuous peripheral nerve blocks (CPNB) extend analgesia well into the postoperative period 1
• Blocks provide site-specific analgesia without systemic side effects 4
• Duration of sensory blockade can range from 3.7 to 14.4 hours depending on technique and concentration 5

Clinical Applications and Specific Scenarios

Orthopedic Surgery

For procedures like hip fracture repair or proximal femoral nail (PFN) insertion, combining femoral, sciatic, and obturator nerve blocks with general anesthesia provides complete surgical anesthesia and extended postoperative analgesia 4. This combination is particularly valuable when:

• Neuraxial anesthesia is contraindicated due to coagulopathy (INR >1.4, platelets <75,000) 3
• Patient positioning makes spinal anesthesia technically difficult 3
• The surgical procedure requires complete muscle relaxation and airway control 4

Thoracic Surgery

Paravertebral or intercostal nerve blocks combined with general anesthesia reduce anesthetic requirements and improve oxygen saturation during video-assisted thoracoscopic surgery (VATS) 2. Benefits include:

• Lower expiratory fraction of sevoflurane required (anaesthetic sparing) 2
• Reduced fentanyl requirements intraoperatively 2
• Faster recovery times with earlier spontaneous movement and laryngeal mask removal 2

Patients with Obstructive Sleep Apnea

For superficial procedures in OSA patients, local anesthesia or peripheral nerve blocks with moderate sedation should be considered, but when general anesthesia is required, adding regional blocks reduces postoperative respiratory complications 1. The approach should prioritize:

• Minimizing systemic opioids to reduce respiratory depression 1
• Using regional techniques that avoid sympathetic blockade 1
• Ensuring full reversal of neuromuscular blockade before extubation 1

Technical Considerations

Block Selection Based on Risk Profile

Peripheral nerve blocks are categorized as low-risk (femoral, popliteal sciatic) or high-risk (infraclavicular, parasacral sciatic) based on hemorrhage risk and compressibility 4. For anticoagulated patients:

• Low-risk blocks may be performed if benefit/risk ratio is favorable 4
• High-risk blocks are contraindicated unless anticoagulation is adequately reversed 4
• This flexibility allows regional anesthesia even when neuraxial techniques are prohibited 4

Ultrasound Guidance

Ultrasound guidance is strongly recommended to reduce local anesthetic systemic toxicity, improve needle placement accuracy, and allow reduced volumes of local anesthetic 4, 3. Technical recommendations include:

• Use in-plane needling along the visual axis for improved speed and accuracy 6, 4
• Calculate safe dose based on patient weight to prevent systemic toxicity 6, 4
• Position ultrasound machine in front of operator rather than perpendicular 6

Local Anesthetic Selection

Amide local anesthetics (ropivacaine, bupivacaine) are preferable to esters for peripheral nerve blocks 1. Key considerations:

• Ester local anesthetics are degraded by plasma cholinesterase, which may be inhibited in certain clinical scenarios 1
• Ropivacaine 0.5% provides effective peripheral nerve blockade with median duration of 3.7 to 8.7 hours 5
• Ropivacaine 0.75% provides anesthesia duration of 11.4 to 14.4 hours for brachial plexus blocks 5

Advantages Over Alternative Approaches

Compared to General Anesthesia Alone

• Reduced total opioid consumption decreases respiratory depression and improves recovery quality 1, 2
• Lower volatile anesthetic requirements reduce postoperative cognitive dysfunction risk 2
• Extended postoperative analgesia without continuous IV opioid infusions 1

Compared to Neuraxial Anesthesia Alone

• Peripheral blocks avoid sympathectomy-induced hypotension 3
• No risk of post-dural puncture headache 3
• Can be performed in anticoagulated patients when neuraxial techniques are contraindicated 4, 3
• Fewer physiological and hemodynamic side effects 4

Compared to Combined Neuraxial and General Anesthesia

• Simultaneous administration of spinal and general anesthesia is associated with precipitous falls in intraoperative blood pressure 3
• Peripheral blocks provide similar analgesic benefits without additive sympathetic blockade 4, 3
• Lower risk profile in hemodynamically unstable patients 3

Common Pitfalls and How to Avoid Them

Inadequate Block Assessment

Thoroughly test for block success before proceeding with surgery 6, 4. Do not assume the block is working based on time elapsed alone—verify sensory and motor blockade in the appropriate distribution.

Positioning-Related Nerve Injury

Avoid compression near the fibular head during patient positioning to prevent peroneal neuropathy 6. Proper padding and positioning checks are essential when patients are under general anesthesia and cannot report discomfort.

Local Anesthetic Systemic Toxicity

Have resuscitation equipment immediately available and monitor blood pressure and electrocardiogram, especially in high cardiovascular risk patients 4. Use ultrasound guidance to minimize this risk 6, 4.

Inadequate Postoperative Monitoring

Patients receiving combined techniques still require appropriate postoperative monitoring, particularly OSA patients who remain at risk for respiratory complications despite regional analgesia 1. Continue monitoring in the semi-upright position and verify adequate oxygenation 1.

Perineural Adjuvant Risks

Balance the benefit of perineural adjuvants (dexamethasone, clonidine) against risks of immunosuppression, sedation, bradycardia, and hypotension 6. Consider these additives carefully in elderly or hemodynamically compromised patients.

Practical Algorithm for Decision-Making

1. Determine if general anesthesia with secure airway is required:

   • Airway-compromising procedures → GETI mandatory 1
   • OSA patients with deep sedation risk → GETI preferred 1
   • Patient cooperation impossible → GETI required 1

2. Assess suitability for peripheral nerve blocks:

   • Check coagulation status (low-risk blocks acceptable with mild coagulopathy) 4
   • Identify surgical site and required nerve coverage 4
   • Verify no local infection at injection site 3

3. Select appropriate block(s):

   • Match nerve distribution to surgical field 4
   • Choose low-risk blocks when possible in anticoagulated patients 4
   • Use ultrasound guidance for all blocks 6, 4, 3

4. Optimize timing:

   • Perform blocks before induction for maximum intraoperative benefit 2
   • Alternative: place blocks after induction if patient cooperation is problematic 2

5. Adjust general anesthetic accordingly:

   • Reduce volatile anesthetic concentration based on block success 2
   • Minimize intraoperative opioids 2
   • Plan for awake extubation with full neuromuscular reversal 1