Brachial Plexus Blocks — Interscalene, Supraclav, Infraclav, Axillary + Phrenic-Sparing

Roots (C5-T1) → trunks (upper, middle, lower) at interscalene groove → divisions (anterior, posterior) behind clavicle → cords (lateral, posterior, medial) lateral to first rib + medial to coracoid → terminal branches (musculocutaneous, axillary, radial, median, ulnar) at axilla.

Mnemonic: Real Texans Drink Cold Beer (Roots, Trunks, Divisions, Cords, Branches).

Block level determines which branches are reliably captured.

Sonoanatomy: 'stoplight' sign — three round hypoechoic structures (C5, C6 upper trunk, C7) between scalene muscles.

SPARES ulnar nerve (C8-T1) — unreliable for forearm/hand surgery.

Volume: 10-20 mL ropi 0.5% or bupi 0.5%.

Hallmark complication: 100% PHRENIC NERVE PARALYSIS at full volume — diaphragm paralysis lasts duration of block (10-24 hr); 25-30% FVC reduction.

CONTRAINDICATED in severe COPD, severe restrictive lung disease, contralateral diaphragm paralysis, contralateral pneumothorax.

For shoulder surgery in patients with marginal pulmonary reserve where interscalene is otherwise indicated: (1) Low-volume interscalene 5-7 mL at exact target — reduces phrenic paralysis to ~40-60% while preserving shoulder analgesia.

Choose based on duration + density needed.

Sonoanatomy: 'cluster of grapes' — hypoechoic plexus lateral + superficial to pulsing subclavian artery, with hyperechoic first rib + pleura immediately deep.

Volume: 20-25 mL ropi 0.5% or bupi 0.5%.

Phrenic paralysis 50-67% (less than interscalene because phrenic-bound fibers have already left at this level).

Pneumothorax was the historic feared complication (1-6% pre-US era); modern US-guided rates <0.5%.

Use the first rib as a hyperechoic backstop — keep needle tip above + lateral to rib, never aim medially toward dome of pleura.

Sonoanatomy: pulsing axillary artery at depth 3-5 cm; cords appear as hyperechoic 'wedges' at 9 o'clock (lateral), 6 o'clock (posterior), 3 o'clock (medial) positions.

Volume: 20-30 mL deposited posterior to artery first ('U-shape' spread).

Patient can keep arm at side.

Preferred for COPD patients needing forearm surgery.

Sonoanatomy: axillary artery + vein at 3-5 cm depth in axilla; median at 10-12 o'clock, ulnar at 6 o'clock, radial at 6-8 o'clock posterior to artery.

Volume: 5-7 mL per nerve + separate 5-7 mL into coracobrachialis for musculocutaneous = ~25-30 mL total.

Failure rate higher than supraclav unless musculocutaneous separately injected (musculocutaneous leaves the sheath above axilla and is missed by trans-sheath injection).

The axillary approach is the right answer for COPD patient needing hand surgery.

A 70 kg patient receiving 30 mL of bupivacaine 0.5% (150 mg = 2.1 mg/kg) is near the limit — for higher-volume blocks (supraclav + intercostobrachial supplement), dilute to 0.375% or split between agents.