The anatomy of children’s airways changes markedly from infancy to adulthood. With growth and development, not only does the airway diameter increase, but the shapes and angles of various structures undergo a number of changes as well. The marked differences in anatomy for various age groups require that a wide variety of equipment be available. Infants in particular, with their relatively large tongue and smaller upper airway diameter, are predisposed to obstruction during induction of anesthesia. It is prudent to have multiple sizes available of oral airways, endotracheal tubes (ETTs) (both with and without cuffs), and laryngeal mask airways (LMAs). Charts can be used as guides, but because of individual variation, it is prudent to have several sizes readily available (Table 46.1).

Ventilation of pediatric patients also deserves consideration. Because of their higher oxygen consumption and high metabolic rates, neonates require much more oxygen than do adults. To meet this requirement, infants and children increase the frequency with which they breathe (breaths/minute). The relative size of each breath (per kilogram of body weight) is similar to that of adults. This is important to remember when setting up the ventilator between cases or assisting with bag-mask ventilation: pediatric patients need a higher respiratory rate (RR), and the tidal volume will depend upon the size of the patient.

The cardiovascular system of children undergoes dramatic changes during growth and development. Prior to birth, infants’ blood receives oxygen from the mother’s placenta rather than from their lungs. To facilitate this, the fetal circulatory system has two “short cuts” (the foramen ovale and the ductus arteriosus) to shunt blood away from the lungs, which are not yet functioning. At birth, these close off, sending more blood to the newly functioning lungs. Because of their increased oxygen consumption, infants pump more blood per unit of weight per minute than do adults. This is accomplished mostly by an increased heart rate (HR).

Differences in the central nervous system of pediatric patients include greater brain water content, a higher ratio of brain content to cranial capacity, and less cerebrospinal fluid (CSF) volume than adults.

The hepatic and renal systems of infants are likewise different from those of adults, and change with development. The fluid and caloric requirements are much higher in infancy. Smaller babies are at increased risk of both dehydration and overhydration, and meticulous attention to accurate measurements of administered fluids is important. Infant intravenous (IV) sets typically contain buretrols to facilitate careful measurement of fluid delivered. For a number of anatomic and physiologic reasons, infants are also at increased risk for
hypothermia during anesthesia and surgery. It is essential to prevent the increased heat loss by warming the operating rooms (ORs), covering the babies with blankets, and using convection forced air warmers.

For children, the anxiety regarding surgery and its associated pain is often compounded by fear of separation from family, and cognitive limitations, which may impair their ability to understand the purpose of the anesthesia and surgery. Because of this, pediatric caregivers employ a number of techniques to minimize the stress experienced by pediatric patients. For example, attempts are generally made to make the general environment appear “kid friendly.” This can be done with soothing and entertaining pictures on the walls and ceilings, available toys for the children to play with, and even entertainment in the preoperative area (i.e., video games, live music). In addition, because children’s anxiety may be shared by their parents, an effort is made to provide the children’s parents with support. This can be facilitated with pamphlets, preoperative discussions with parents, and sometimes even tours of the various preoperative and postoperative areas.

Finally, a number of measures are employed with the children themselves to lessen their anxiety and discomfort. Discussions with children are conducted using age-appropriate concepts and vocabulary. For example, children aged 2-4 years are often eager to engage in fantasy and magical thinking, and brighten at the prospect of “being told a story” in the OR. Older children may be helped by being given the choices, (i.e., a “flavor” for their breathing mask). Adolescents are very often concerned about waking up during surgery, and respond well to reassuring discussions.

Children between the ages of 1 and 3 years are at the highest risk of emotional trauma upon separation from their parents, or upon being shown either a needle (for injection) or an anesthetic mask. Not only are children in this age group at risk for stormy anesthetic inductions, but they are also at increased risk for postoperative behavioral changes (i.e., tantrums, nightmares, regression in potty training), which can last weeks to months. With this in mind, pediatric facilities may include “induction rooms” separate from the surgical suites in which children can be anesthetized with a parent present. General anesthesia is typically induced by having the child breathe increasing concentrations of anesthetic agent; IV lines are often not started until after children are unconscious. Another strategy for calming children prior to separation from their families is the use of oral premedication, which is seldom administered in the adult population. Oral midazolam has been shown to greatly reduce separation anxiety and resisting the mask in the OR. In addition, there is evidence that this
premedication lowers the incidence of untoward postoperative behavior changes.

Marked changes in anatomy and physiology occur from birth to adolescence. However, similar anesthesia equipment is used in patients of all ages. The differences in airway equipment and vascular catheters are chiefly in size rather than shape or type (Figs 46.1, 46.2 and 46.3).

In addition, IV administration kits for children younger than about 10 years of age feature “microdrips” and buretrols to help prevent fluid overload (Figs. 46.4 and 46.5).

Children in general greatly fear needles. Hence, in most hospitals, the majority of children younger than about 12 years of age are brought to the OR without an IV having been inserted. General anesthesia is typically induced by having the child breathe oxygen with increasing percentages of anesthetic gases (nitrous oxide, sevoflurane) added. IVs are placed after the children are anesthetized.

It is important to understand that during the initial period, while the anesthesia is “light,” the child is at greatest risk for adverse airway events. These include laryngospasm, apnea, and airway obstruction. This is particularly true prior to the insertion of the IV, as there is not yet a method of rapidly administering medications emergently.

Anesthesia-related morbidity and mortality are higher in infants, particularly the neonate. To reduce this risk requires a well-planned technique and a thorough understanding of the specific pathophysiologic conditions and surgical needs. The unique demands of infancy will require the appropriate age-related equipment and expertise that are best met by personnel trained to provide care to pediatric patients, neonates, and infants on a regular basis.