Thoracic Paravertebral Space Block
The thoracic paravertebral space block is a useful technique to
provide unilateral analgesia of the chest, especially during and after thoracic surgery
because a catheter can be left in place for long-lasting pain relief.[274]
[275]
[276]
The
paravertebral space is a wedge-shaped space lying on either side of the vertebral
column. It is limited by the vertebral bodies and intervertebral disks medially.
The transverse processes, the ribs, and the costotransverse ligaments are positioned
posteriorly, and the parietal pleura are located anterolaterally. The apex of the
space is continuous with the intercostal spaces. the endothoracic fascia adheres
to the ribs and fuses medially with the periosteum of the vertebral bodies. A free
communication often exists between the lower thoracic paravertebral region and the
celiac ganglion that may represent a possible route of spread for local anesthetic
administered in the lower part of the thoracic paravertebral space.[277]
In pediatrics, the patient is placed in the lateral decubitus
position, resting on the nonoperated side. The landmarks are the spinous and transverse
processes of T7 to T9 (for thoracotomy, the block is performed between the T4 and
T6 levels), and the puncture site is marked 1 to 2 cm lateral to the spinous process
( Fig. 45-23
). The same
Tuohy needle that would be used for performing an epidural in the patient is inserted
at right angles to the skin while continuous pressure is exerted on the barrel of
the LOR syringe, which is connected to the block needle and filled with saline, until
it contacts the transverse process. The needle is then walked along the surface
of the process and eventually passes over its cranial border and enters the paravertebral
space after piercing the costotransverse ligament with a clearly identifiable LOR.
An epidural catheter is then inserted for 2 to 3 cm and, after a negative aspiration
test result and test dose, is securely taped on the skin, as for a
Figure 45-23
Block of the thoracic paravertebral space, identifying
the parietal pleura (1) and a rib (2).
continuous epidural. A starting dose of 0.5 mL/kg of 0.25% bupivacaine or 0.2% to
0.5% ropivacaine is then injected, followed by reinjection or continuous infusion
of the same local anesthetic (0.25 mL/kg/hour). The technique compares favorably
with continuous interpleural anesthesia.[278]
Its
failure rate is low, and complications are uncommon,[277]
[278]
[279]
including
pleural puncture, dural puncture, hypotension (in adults), seizures due to inadvertent
vascular penetration, and epidural spread with Horner's syndrome.
