Chapter 76 Truncal Blocks: Intercostal, Paravertebral, Interpleural, Suprascapular, Ilioinguinal, and Iliohypogastric Nerve Blocks Flashcards
KEY POINTS 1. When compared to epidural analgesia for thoracotomy, paravertebral blocks with catheters provide equipotent analgesia with a lower incidence of pulmonary complications, hypotension, urinary retention, nausea and vomiting, and failure rate. 2. A single injection of 15 ml in a thoracic paravertebral space can be expected to provide analgesia over 3 to 4.6 dermatomes, with a preferential caudad spread of injectate. 3. Ultrasound imaging usually underestimates the distance to the tr
Epidural analgesia when compared to
paravertebral blocks for patients undergoing thoracotomy
fewer side effects including
pulmonary complications, hypotension, urinary
retention, and nausea and vomiting.
paravertebral (PV) space
wedge-shaped area adjacent
to the vertebral column that contains the sympathetic
chain, the dorsal and ventral (intercostal) roots of the spinal
nerve, the white rami communicantes as well as fatty
tissue and intercostal vessels
The base of the wedge constitutes
the medial border of the paravertebralspace and is formed by the vertebral body and the intervertebral
disc where there is communication with the epidural space via the intervertebral foramen
The posterior border of the PV space
the superior costotransverse ligament which extends laterally to become continuous with the aponeurosis of the internal intercostal muscle.
internal intercostal membrane runs
between the ribs
superior costotransverse ligament runs from
the inferior border of the transverse process above to the superior border of the rib tubercle below.
As the wedge tapers off
laterally, it is continuous with the
intercostal space
Anterior and lateral to the PV space is the
parietal pleura
Within the paravertebral space, the spinal nerves
do not have a fascial sheath and are easily susceptible
to local anesthetic blockade. There is however the endothoracic fascia, which is the deep investing fascia of the
thoracic cavity, within the PV space that can affect the
spread of injected solutions.
Conventional techniques have described
loss-of-resistance approach to reach the PV space. A small-gauge Tuohy needle is inserted 2.5 cm lateral to the
superior edge of the spinous process perpendicular to all
planes and advanced until contact is made with the transverse process (TP). The needle is then withdrawn to the skin, redirected caudad or cephalad by 15 degrees and advanced deep to the superior costotransverse ligament at which point loss of resistance is achieved. To avoid pleural puncture, the needle
is advanced 1 cm (and no further than 1.5 cm) past the point at which the TP was contacted
It is best to avoid medial and lateral angulation of the needle to minimize the risk of
It is best to avoid medial
angulation of the needle to minimize the risk of local
anesthetic injection into a dural sleeve. It is also prudent to
avoid lateral angulation given that the PV space is narrower
laterally increasing the risk of pleural puncture
Three US-guided approaches have been described.
The first approach utilizes US primarily to identify
the TP.
Once the TP is contacted under US guidance, the conventional loss-of-resistance technique is utilized. To visualize the TP, the US probe is placed in a longitudinal
parasagittal plane 2.5 cm from the midline. Generally, a 5- to 10-degree tilt laterally is needed to best visualize the TP, which appears as concave hyperechoic structure
approximately 1 cm wide with anechoic space deep to
it. This is commonly referred to as a “thumbprint sign.”
The parietal pleura can be visualized approximately 1 cm
deep to the TP on either side as a sharp hyperechoic line. Initial contact with the TP should be made with a 22-gauge finder needle that can serve to infiltrate local anesthetic. Generous local anesthetic infiltration is recommended to minimize paraspinal muscle discomfort and can serve to echolocate the needle tip. Once the TP is contacted with the finder needle, the depth is noted and a Tuohy needle or blunt-bevel block needle is introduced. Using an out-of-plane needle approach and similar to the
conventional technique, the TP process is contacted and
then redirected caudad 1 cm (and no more than 1.5 cm)
past the TP. Loss of resistance to saline is confirmed and
local anesthetic injection is performed
The first approach utilizes US primarily to identify the TP. To minimize the risk of pleural puncture and development of pneumothorax,
it is useful to have a needle with centimeter markings and a closed needle-syringe system relative to atmospheric pressure.
The second approach is a slight variation of the first and
utilizes an in-plane or out-of-plane approach to the PV
space
The probe is in the identical longitudinal parasagittal
plane and the PV space is approached directly without first contacting the TP process. a “pop” may be felt when the posterior costotransverse ligament is traversed with corresponding loss of resistance
In the third approach, the TP is initially imaged with
a similar longitudinal parasagittal view, and the probe is then rotated obliquely to allow for the best view of the posterior costotransverse ligament and the PV wedge. The needle is advanced carefully utilizing an in-plane needle approach
PV Block DOSING
A single injection of 15 ml can be expected to provide analgesia over 3 to 4.6 dermatomes in the thoracic region. Spread is initially at the level of injection and
along the intercostal nerve, and progresses in the PV “gutter” to cover one dermatome above and two dermatomes
below.
PV Block Analgesia last for
typically ranges from 6 to 12 hr for a single injection. If a catheter is placed, infusion
of ropivacaine 0.2% to 0.5% at rates of 4 to 8 ml/hr may
be used
PV Block COMPLICATIONS
Pneumothorax is estimated to occur in up to 0.5% of
patients, yet most are not clinically significant and can be
managed conservatively. most
patients will present with a sudden irritating cough or
sharp pain in the chest. Vascular puncture
If the parietal pleura is violated, the
block can be converted
to an intrapleural block
Life-threatening complications from PV blocks
have occurred as a result of bolus dosing. A bolus dose can accidentally be injected into the intrathecal or epidural
space, or into a blood vessel. bolus dosing with subsequent intrathecal or intravascular
spread—and not pneumothorax
intercostal blocks can be used to provide chest
wall analgesia In patients with
spinal anomalies, trauma, or previous spine surgery
INTERCOSTAL NERVE BLOCK
ANATOMY
As nerves leave the PV space, they enter the intercostal
space and lie between the innermost intercostal muscle
and the pleura
primary landmark for intercostal nerve block
Lateral to the paravertebral muscles, the prominent angles of the ribs are palpable
At the angle of the
rib, the nerve lies between
the innermost intercostal muscle
and the inner intercostal muscle
Classically the intercostal nerves
have been thought to lie
caudad to the intercostal vein and artery, on the inferior portion of the rib.
Most of the T1 nerve fibers combine with
C8 to form the lower trunk of the brachial plexus.
form the intercostobrachial nerve that supplies the upper chest wall along with cervical fibers
from the brachial plexus.
Fibers from T2 and T3
Intercostal nerves T4–T11 supply
the
thoracoabdominal wall from the nipple line to below the umbilicus.
The T12 nerve is actually a subcostal nerve that contributes branches to the
iliohypogastric and
ilioinguinal nerves
INTERCOSTAL NERVE BLOCK
TECHNIQUE
(Patient’s position)
The ideal patient position is prone, with a pillow under the
abdomen and both upper extremities hanging over the sides of the table, which maximizes retraction of the scapulae away from the upper ribs. This allows for bilateral blockade and posterior access to the angles of the ribs to enhance safety and success of the procedure. The lateral decubitus position is also quite satisfactory for unilateral blockade after rib fractures and lateral thoracotomy as well as for chest tube placement. The supine position may also be utilized
for bilateral block at the level of the midaxillary line;
however, the rib and intercostal space are narrower here
INTERCOSTAL NERVE BLOCK
Classic TECHNIQUE
locating the angle of the rib (approximately 8 cm lateral to the midline) and using a 22-gauge, short-bevel needle to walk off 3 mm deep
to the lower costal margin, and repeating this at the desired
levels.
