General Considerations for Pediatric Peripheral Blocks

Ovid: Peripheral Nerve Blocks: A Color Atlas

Editors: Chelly, Jacques E.
Title: Peripheral Nerve Blocks: A Color Atlas, 3rd Edition
> Table of Contents > Section V
– Pediatric Peripheral Blocks > 44 – General Considerations for
Pediatric Peripheral Blocks

General Considerations for Pediatric Peripheral Blocks
Giorgio Ivani
Valeria Mossetti
Many factors have contributed to the wide diffusion of
regional anesthesia in children: the awareness of pain and the
subsequent need for adequate pain relief at any age—from premature
babies to adolescents—the demonstration of the efficacy of regional
anesthesia in controlling stress, the vast amount of information coming
from congresses, and books and papers on this topic. Notwithstanding
the criticism surrounding the use of a “double anesthesia” (most blocks
in children require sedation or light anesthesia before performing the
block) with the supposed “double risk,” evidence from the world of
pediatric anesthesia has demonstrated that regional anaesthesia in
children is safe. Safety depends on experience and adequate guidelines,
but also on the choice of drugs, whose main characteristic must be a
reduced toxicity, and on a multimodal approach, which allows low
concentrations of multiple drugs for a synergistic action. Some
regional blocks, such as caudal blocks, epidural blocks, or penile
blocks, have already an established place in pediatric anesthesia,
mainly as techniques of postoperative analgesia. Peripheral nerve
blocks are not yet as popular but the interest in this technique is
growing due to their safety, efficacy, and well-limited localization of
Regional anesthesia performed on children presents some
differences to that performed on adults because of particular pediatric
issues; therefore, to perform peripheral blocks in children some
differences from the practice in adults should be considered.
The first obvious anatomic difference between adults and
children is the size of the patient; therefore the practitioner must
locate peripheral nerves with slow movements and use micro adjustments
for precision. Another difference is linked to the anatomic landmarks
because the anatomic relationships vary depending on age; moreover, the
bony growth is not the same for long, short, or flat bones, and the
variations of body fluids affect skin thickness. Therefore, the length
of the needle should be the shortest that can easily reach the nerve to
be blocked. Despite the potential difficulties that may arise from the
anatomic differences in children, there are also anatomic benefits that
are offered in the developing child. One such benefit is the ease with
which nerves are blocked by local anesthetics due


their thin myelin sheaths, small fiber diameter, and short internodal
distances. This allows lower concentrations of local anesthetic to
produce an adequate surgical block in infants and younger children. On
the other hand, this may lead to an increased risk of toxicity if the
dose is not appropriately adjusted. Another anatomic benefit in the
pediatric patient is the presence of loose connective tissue around
neuroaxial structures centrally, and nerve sheaths that are only
loosely attached to the nerve trunks peripherally. These factors should
lead to an improved spread of local anesthetic without the dense
anatomic barriers that may be present in adults.

We must consider that in newborns and children there is
a lower level of alpha-1-glicoprotein, which means a higher fraction of
free local anesthetic. There are also considerable individual
variations and little information concerning diffusion, protein
binding, and local metabolism; moreover, local spread is easier in
children because of the age-related increase in cardiac output and
regional blood flow, and fat is less dense. As in adults, absorption
depends on the site of injection and increases in the following order:
proximal nerve blocks of the lower extremities, brachial plexus blocks,
caudal blocks, epidural blocks, intercostal blocks, and topical
laryngeal applications.
Assessment of Pain
It is difficult to evaluate pain in newborns, infants,
preverbal age, or impaired children. The verbal and visual
understanding is limited but pain can be identified through
observational items: crying, facial expression, posture of the trunk,
posture of the legs, and motor restlessness. For older children, pain
can be assessed through the Faces Pain Rating Scale, a pictogram of six
faces with different expressions from smiling or happy through to
Combined Regional and General Anesthesia
Children have fear of needles, and any performance of a
block on a screaming, moving child is not only unethical, but could be
dangerous when the needle approaches the delicate neural structures. It
is therefore mandatory to associate most regional block procedures with
general anesthesia. But performing a block on a deeply sedated child
could be dangerous as well: any warning signals that something is going
wrong could be easily missed. Therefore, deep anesthesia should be
avoided before the performance of a block; a light general anesthesia,
without muscle relaxation or injection of narcotic, guarantees
immobility and avoids the dangerous untoward effects related to
respiratory and circulatory failures as well as the adverse events that
could result from a faulty technique, such as excruciating pain,
convulsions, or tachycardia.

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