53.5 Technique

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Transducer position

Select the target transverse process for the block.
Place the transducer in a paramedian sagittal orientation, approximately 2 cm away from the midline (spinous processes).

Essential fact:
At higher thoracic levels, e.g., above T5; trapezius, rhomboid major and erector spinal muscles can be identified as three layers superficial to the transverse processes. In the lower and mid-thoracic levels, only trapezius and erector spinae muscles can be seen.

Scanning

Visualize the transverse process.

TP, transverse process; PVS, paravertebral space.

Common problems and solutions:

If the transducer is placed too medial, the thoracic laminae will be visualized as flat hyperechoic lines (A). To fix: Slowly slide the transducer laterally (B).

When the transducer is placed too lateral, ribs will be visualized as rounded acoustic shadows with an intermediate hyperechoic pleural line (C). To fix: Slowly slide the transducer medially (B).

A. Transducer too medial. B. Adequate transducer position for an ESP block. C. Transducer too lateral. ESP, erector spinae muscles; TP, transverse process; PVS, paravertebral space.

Tips

At higher thoracic levels, e.g., above T5; trapezius, rhomboid major, and erector spinae muscles can be identified as three layers superficial to the transverse processes.

In the lower and mid-thoracic levels, only trapezius and erector spinae muscles can be seen.

Typically the rib-transverse process complex can be identified as a flat squared hyperechoic line with an acoustic shadow behind.

Also, note that the pleura should not be visualized at the level where the block is performed.

Needle insertion

Insert the needle in-plane from a cranial to caudad direction until the needle tip contacts the transverse process.

Inject 1-3 mL of local anesthetic to confirm proper injection plane by visualization of a spread deep to the erector spinae muscles and superficial to the transverse process.

Complete the block with 20-30 mL of local anesthetic.

Let’s review the block: