Understanding Anesthesiology - The Global Regional Anesthesia ...

SECTION 3
Pediatric Anesthesia
In This Section
1. Physiology of the Pediatric
Patient
Not just a small adult...
The principles of pre-operative assessment, anesthetic
management and post-operative care described
earlier apply equally well to the pediatric
patient. Specific variations in management of the
pediatric patient result from differences in anatomy
and physiology in this patient population, as
compared to adult patients. Some of these differences
are discussed briefly below.
Respiratory System
The pediatric airway differs from the adult airway
in several respects. The occiput is relatively
prominent in infants and young children. This
means that the “sniffing position” is often best
achieved with the head in the neutral position,
without the use of a pillow. The relatively large
tongue may hinder visualization of the larynx or
contribute to upper airway obstruction under anesthesia.
The epiglottis is long, angled and mobile.
Because of this, a Magill blade is often used
(in infants and young children) to lift the epiglottis
directly to expose the larynx. The larynx itself
is positioned higher (C4 vs. C6 in adult) and more
anteriorly. The narrowest part of the pediatric airway
is the subglottic region, at the level of the cricoid
cartilage. Therefore, the use of a cuffed endotracheal
tube (ETT) in a child less than 10 years of
age is unnecessary and undesirable, as the narrow
subglottic region provides its own seal. Because
the trachea is narrowed, short and easily
traumatized, appropriate selection of an ETT is
critical. Recommended sizes of ETT by age are indicated
in Table 18. Generally, the formula below
predicts the correct tube size for children over one
year of age.
ETT size = 4+ (age/4)
The pediatric airway is relatively more prone to
obstruction than the adult airway. Infants are obligate
nose breathers and the nares are small and
easily obstructed by edema or mucous. Due to
subglottic narrowing, a small amount of edema
resulting from ETT trauma or pre-existing infection
(trachiitis or croup) can seriously compromise
airway patency. Finally, laryngospasm is
common in children. This complex and potentially
life-threatening phenomenon can result
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