External oblique intercostal plane block

2019 by Elsharkawy et al.

Anatomy

Anterolateral upper abd wall innervation : ventral rami of T6 - T10
- Two key branches of intercostal nerves
  - Lateral cutaneous
  - Anterior cutaneous
External oblique
- Thin broad muscle
- Spanning both thorax & abd
- Originates on external surfaces of ribs 5-12
- Form digitations w/ serratus anterior & latissimus dorsi
- Courses anteriorly from midclavicular line à form aponeurosis à becomes part of ant rectus sheath
Spinal nerves T6 - T9
- Emerge from costal margin into plane btw IO & TA
- Then enter lateral border of rectus sheath à terminate as anterior cutaneous branches

Superficial
- Ease to perform
- Safe in anticoagulated pt
- Less affected by body habitus
  - <4cm deep
Not interfere w/ surgical incision
USG image not disrupted by surgical incision
Performed supine

Anterior axillary line
Level of xiphoid process
- → 6th rib
EO confirmed by:
- Tracing to subcostal TAP view
- Move probe laterally to visualise junction btw serratus anterior & EO
possibility of landmark technique