PT  - JOURNAL ARTICLE
AU  - Diwan, Sandeep
AU  - Gupta, Anju
AU  - Shivamallappa, Shivprakash
AU  - Timane, Rasika
AU  - Pai, Pallavi
TI  - EP220 Pathways of dye spread after ultrasound guided injections in the paraspinal spaces- A Cadaveric study
AID  - 10.1136/rapm-2023-ESRA.280
DP  - 2023 Sep 01
TA  - Regional Anesthesia & Pain Medicine
PG  - A159--A160
VI  - 48
IP  - Suppl 1
4099  - http://rapm.bmj.com/content/48/Suppl_1/A159.2.short
4100  - http://rapm.bmj.com/content/48/Suppl_1/A159.2.full
SO  - Reg Anesth Pain Med2023 Sep 01; 48
AB  - Background and Aims The exact mechanism of action of erector spinae plane (ESP) block remains an enigma. We injected dye in ESP and other paraspinal spaces to compare the dye diffusion pattern along the paraspinal region in human cadavers.Methods In 6 soft-embalmed cadavers(12 specimens), 20mL methylene blue dye (ESP and paravertebral space) or indocyanine green dye (inter-ligament space) was injected bilaterally using an in-plane ultrasound-guided technique at the level of the costotransverse junction of T4 vertebrae. Dye spread was evaluated bilaterally in the coronal plane in the paravertebral and intercostal spaces from the 1st and the 12th rib. Axial and sagittal sections were performed at the level of the 4th thoracic vertebrae. After cross-sections, the extent of dye spread was investigated in the ESP, inter- ligament and paravertebral spaces. The staining of the ventral and dorsal rami and spread into the intercostal spaces were also evaluated.Results The ESP injection was mainly restricted dorsal to the costotransverse foramen and did not spread anteriorly to the paravertebral space. The paravertebral injection involved the origin of the spinal nerve and spread laterally to the intercostal space. The inter-ligament space injection showed an extensive anterior and posterior dye spread involving the ventral and dorsal rami. (figure1)Abstract EP220 Figure 1 Dye spread in interligamentous spaceConclusions Following injections in erector spinae plane, there was no spread of the dye anteriorly to the paravertebral space and it only involved the dorsal rami. Inter-ligamentous space injection appears to be the most promising block in future as the dye spread both anteriorly to paravertebral space and posteriorly toward the erector spinae plane.