Upper limb regional anaesthesia: brachial plexus approaches

Model answer

Framing. Match the brachial plexus approach to surgical territory: interscalene for shoulder (accept phrenic block — classically 100 percent paresis, cut to 13 percent by low-dose ultrasound technique at C7), supraclavicular for arm/forearm with pneumothorax risk, infraclavicular for below-elbow work and catheters (higher success than supraclavicular, OR 0.61, with less diaphragmatic risk), axillary for the hand with the musculocutaneous blocked separately; use ultrasound, dose limits, and ASRA LAST rescue with lipid emulsion per protocol^[1][4][5][6].

Must cover.

• Anatomy of brachial plexus roots trunks divisions cords branches (standard teaching; approach comparisons trial-owned)^[4]
• Interscalene indications and phrenic nerve paresis (Petrar: complete paresis 34 percent supraclavicular vs 3 percent infraclavicular; Renes: 13 vs 93 percent ultrasound vs nerve-stimulation interscalene)^[5][6]
• Supraclavicular vs infraclavicular vs axillary decision matrix (Muir 18 RCTs, 1389 patients: infraclavicular higher success)^[4]
• Ultrasound technique principles and LA dose limits (trial arms: 30 mL 0.5 percent ropivacaine SC vs IC; 15 mL 0.5 percent single vs multiple-point; 10 mL 0.75 percent low-dose interscalene; ceilings per formulary)^[5][6][7]
• LAST prevention and lipid-emulsion rescue per protocol (ASRA advisory: ultrasound prevention, delayed-presentation trend, small-size/sarcopenia risk; lipid 1.5 mL/kg lean body weight)^[1]
• Anticoagulation considerations for deep blocks (ASRA fourth-edition drug-specific timing)^[2]
• Catheter techniques and continuous infusions (per local protocol)^[2]
• Failed block rescue strategy (Mangal: single-point success 60.8 vs 98 percent multiple-point; convert rather than stack to toxicity)^[7]

Crisis. LAST after interscalene or supraclavicular block — stop injection, airway with 100 percent oxygen, benzodiazepine for seizures, lipid 1.5 mL/kg bolus then infusion, prolonged CPR with reduced adrenaline doses^[1].

High-yield numbers/facts. Lipid 1.5 mL/kg lean body weight bolus (ASRA); complete hemidiaphragm paresis 34 vs 3 percent SC vs IC (Petrar); 13 vs 93 percent US vs nerve-stim interscalene (Renes); single- vs multiple-point success 60.8 vs 98 percent (Mangal); infra- vs supraclavicular success OR 0.61 (Muir)^{[1][4][5][6][7]}.