Many significant changes occur as a newborn
baby grows and develops into an adolescent and then an adult. All the physiological and psychological changes are unique to children and have a considerable impact while anesthetizing them. This chapter will help anesthetists to acquaint physiological changes in children along with their anesthetic implications.
Definitions: Pediatric age group ranges from neonate to adolescent as shown in Table 25.1.
Circulatory parameters (heart rate and systolic blood pressure [SBP]) are listed in Table 25.2.
The larynx is high (C3–C4) and anterior. The epiglottis is long, floppy, and U-shaped. It tends to fall posteriorly in the supine position. Unlike the “sniffing” position, the head needs to be in a neutral position to improve the glottic view.
The closing volume is larger than the FRC until 6 to 8 years of age. This causes an increased tendency for airway closure at end-expiration. Thus, neonates and infants generally need positive pressure ventilation (PPV) with positive end-expiratory pressure (PEEP) during anesthesia.
Patent ductus arteriosus (PDA) more common in premature infants; it closes typically 10 days to 2 weeks after birth but may reopen in the first few weeks after
birth whenever pulmonary arterial pressure rises (hypoxemia, hypercarbia, acidosis, etc.), which is known as transitional circulation.
The cardiac output is rate-dependent in neonates and children with reduced capacity to increase stroke volume by premature heart. Therefore, bradycardia is poorly tolerated, and cardiac compression should be provided in the neonate with a heart rate < 60 bpm.
The deficiency of vitamin K-dependent clotting factors and platelets during the first few months of life puts neonates at risk of intracranial bleed. Therefore, vitamin K is given at birth to prevent hemorrhagic disease of the newborn.