Coracoid Approaches to the Brachial Plexus
Coracoid blocks are performed with the child placed in the supine
position,[201]
with the head turned to the opposite
side and the ipsilateral arm resting alongside the body (i.e., paracoracoid approach)
or abducted at a 90-degree angle to the chest (i.e., midclavicular approach). Three
landmarks are identified: the lower border of the clavicle, the coracoid process
of the scapula, and the axillary artery at its emergence from under the clavicle
( Fig. 45-6
). Many variants
of the coracoid approach have been published, but two techniques are reliable and
relatively safe. With the paracoracoid approach,[216]
the site of puncture lies in the lower part of deltopectoral groove, usually identified
by a palpable dimple that is 1 to 2 cm caudal and 0.5 to 1 cm lateral to the coracoid
process of the scapula. The block needle is inserted at right angles to the skin
until muscle twitches are elicited in the upper arm. With the midclavicular approach,
[217]
the site of puncture is located at the midpoint
of the lower border of the clavicle, and the block needle is inserted at a 45- to
60-degree angle to the skin, in the direction of the axilla, until appropriate twitches
are elicited. Location of the brachial plexus can be difficult in some patients,
and some anesthesiologists recommend ultrasound-guided techniques.[218]
TABLE 45-11 -- Recommended volumes of local anesthetic solution for most plexus and proximal
trunk nerve blocks
|
Volumes for Single-Shot Procedures
by Weight |
|
Block |
2–10 kg (mL/kg) |
15 kg (mL) |
20 kg (mL) |
25 kg (mL) |
30 kg (mL) |
40 kg (mL) |
50 kg (mL) |
60 kg (mL) |
> 70 kg (mL) |
|
Parascalene |
1 |
12.5 |
15 |
17.5 |
20 |
22.5 |
25 |
27.5 |
30 |
|
Interscalene |
1 |
12.5 |
15 |
17.5 |
20 |
22.5 |
25 |
27.5 |
30 |
|
Peri-subclavian |
1 |
12.5 |
15 |
17.5 |
20 |
22.5 |
25 |
27.5 |
30 |
|
Axillary |
0.5 |
7.5 |
10 |
10 |
12.5 |
15 |
17.5 |
20 |
25 |
|
Coracoid |
0.5 |
7.5 |
10 |
10 |
12.5 |
15 |
17.5 |
20 |
25 |
|
Lumbar plexus
*
|
1 |
15 |
17.5 |
20 |
20 |
20 |
20 |
20 |
20 |
|
Femoral |
0.7 |
8 |
12 |
15 |
15 |
17.5 |
20 |
22.5 |
25 |
|
Fascia iliaca |
1 |
12.5 |
15 |
17.5 |
20 |
22.5 |
25 |
27.5 |
30 |
|
Proximal sciatic |
1 |
15 |
17.5 |
20 |
22.5 |
25 |
27.5 |
30 |
32–35 |
|
Popliteal fossa |
0.3 |
4 |
5 |
6 |
7.5 |
10 |
10 |
10 |
10 |
*Doses
and volumes of local anesthetics greater that those recommended for epidural anesthesia
must not be injected because of the potential risk of epidural and spinal spread
of the local anesthetics administered by this route.
Both techniques facilitate the placement of a catheter and its
immobilization, even in boisterous children, but none of them is as safe as an axillary
approach, and several complications have been reported, at least in adults.[216]
[219]
[220]
In
practice,
the main complications in adults are pneumothorax, respiratory failure, inadvertent
vascular puncture with systemic toxicity of local anesthetics, and Horner's syndrome.
