Understanding Anesthesiology - The Global Regional Anesthesia ...

tain types of noxious stimuli. Examples include hypoxemia
and laryngoscopy. It is common practice, therefore,
to pre-treat infants and young children with atropine
just prior to the induction of anesthesia. Bradycardia in
the pediatric patient must always be assumed to be a
result of hypoxemia until proven otherwise.
Fluids and Metabolism
Management of fluid requirements follows the same
principles described in the chapter on fluid management.
The “4/2/1 rule” to calculate maintenance requirements
applies equally well to the pediatric patient.
There are some important differences, however.
The blood volume of a child is greater, relative to their
weight, compared to the adult (Table 20). This becomes
important when calculating estimated blood loss as a
percentage of the estimated blood volume as is done to
guide to transfusion therapy.
The second important issue involves the type of maintenance
fluid used. Because of its glucose and sodium
concentrations, 2/3 D5W-1/3 N/S is appropriate for
maintenance fluid administration in adults and children.
In the operating room, we routinely administer
N/S or R/L for maintenance because it is the crystalloid
of choice for replacing blood volume and third
space losses, which make up the bulk of the fluid needs
in the intra-operative period. In infants and young children,
however, it is less appropriate to use N/S or R/L
for maintenance especially during prolonged cases.
Firstly, the immature kidney is unable to handle an excessive
sodium load. Secondly, the child’s liver glycogen
stores may be insufficient to maintain normal serum
glucose during a more prolonged period of fasting.
Table 20 Blood volume
AGE
BLOOD VOLUME
(CC/KG)
preterm neonate 90
term neonate 80
infant 75
child 70
adult 60 - 70
Gastrointestinal
Children, generally speaking, present a lower risk of regurgitation
and aspiration than adult patients. As well,
they will become dehydrated more readily during a period
of fasting. Thus, NPO guidelines for pediatric patients
are more liberal than in the adult population. For
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