Pediatric Anesthesia
Arielle D. Henderson
Pediatric anesthesia is more complex than simply adjusting drug dosages and equipment size.
Pediatric patients have different anesthetic requirements.
A detailed understanding of the anatomic, physiologic, and pharmacologic characteristics of pediatric populations is essential (Figure 4.1).
This chapter will review the anatomy and physiology of pediatric patients, as it pertains to pediatric anesthesia, the pharmacologic differences of pediatric versus adult patients undergoing anesthesia, and various pediatric anesthetic techniques.
RELEVANT ANATOMY AND PHYSIOLOGY
Respiratory System
A comprehensive understanding of the characteristics that differentiate pediatric respiratory anatomy and physiology from those of adults is essential to the practice of pediatric anesthesia.
For one, neonates and infants have fewer and smaller alveoli, thus reducing lung compliance and increasing airway resistance.1
This increases the work of breathing, and in combination with weaker intercostal muscles and weaker diaphragms, respiratory muscles fatigue more easily in patients of this age.
Furthermore, a decreased functional residual capacity (FRC) in neonates and infants results in decreased oxygen reserve during periods of apnea (ie, intubation attempts).2
This puts neonates and infants at an increased risk for atelectasis and hypoxemia.
It is not until late childhood that the alveoli become fully mature (around 8 y of age) (Figure 4.2).
 Figure 4.1Induction of anesthesia. (Reprinted with permission from Holzman RS, Mancuso TJ, Polaner DM. A Practical Approach to Pediatric Anesthesia. 2nd ed. Philadelphia, PA: Wolters Kluwer; 2016.) |
 Figure 4.2 Anatomic differences of infant versus adult airway. (Reprinted with permission from Nichols DG, Ackerman AD, Biagas K, Argent AC, Rogers MC, eds. Rogers’ Textbook of Pediatric Intensive Care. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008.) |
Cardiovascular System
Neonatal hearts are relatively noncompliant given an immature left ventricle, and thus stroke volume is relatively fixed.1
In other words, newborns and infants rely almost entirely on heart rate to manage cardiac output.
This is further complicated by a sympathetic nervous system and baroreceptor reflexes that are not fully mature.3
The immature heart is more susceptible to depression by anesthetics, which can result in intraoperative bradycardia and decreased cardiac output.
Bradycardia and reductions in cardiac output can lead to hypotension, asystole, and intraoperative death for neonates and infants undergoing extended surgical procedures.4
Renal and Gastrointestinal Systems
Neonates have a relatively decreased glomerular filtration rate, thus, impaired creatinine clearance, sodium retention, bicarbonate reabsorption, and impaired diluting and concentrating ability.3
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