Chapter 63. Anesthesia for Newborn Surgical Emergencies

1. Newborns require anesthesia for surgery. Newborns respond to noxious stimuli, and failure to provide analgesia and anesthesia increases perioperative morbidity and mortality

2. Pharmacokinetics and pharmacodynamics differ in newborns. Concentrations of albumin and alpha-1 acid glycoprotein are lower in newborns, and binding sites are fewer; thus, a greater proportion of active ("free") drug is available. Furthermore, the newborn cytochrome P450 system does not reach adult functionality until 1 to 2 months of life.

3. All potent inhalational anesthetics produce unacceptable hypotension in newborns. Thus, the risk of cardiovascular collapse during the induction of general anesthesia is much greater in newborn than in older children and adults.

4. Newborns have a fixed stroke volume and can increase cardiac output only by increasing heart rate. Atropine requirements in newborns (0.03-0.05 mg/kg intravenous [IV]) are almost three times greater than in adults, and total doses of less than 0.1 to 0.15 mg may produce paradoxical bradycardia, further contributing to hypotension.

5. Fentanyl (10-12.5 mcg/kg) produces insignificant hemodynamic changes and provides reliable anesthesia in newborns, provided the infants are preloaded with a balanced salt solution (20 mL/kg IV) and a vagolytic agent (eg, pancuronium or atropine) is administered.

6. Rapid-sequence induction with gentle cricoid pressure, rather than "awake" intubation, is usually the preferred method of securing the airway.

7. Newborns are at high risk for hypothermia during transport and in the operating room (OR). This is countered by wrapping the infant in plastic bags; using forced-air heating mattresses; increasing the OR temperature to or above 90°F, warming IV fluids; and using heated, humidified respiratory gases.

8. "Right-to-left" shunting of blood across the ductus arteriosus and the atrial septum is a catastrophic return to fetal circulation (ie, persistent fetal circulation or persistent pulmonary hypertension of the newborn); it occurs when pulmonary vascular resistance exceeds systemic vascular resistance. Treatment is directed at improving oxygenation and increasing pulmonary blood flow by the judicious use of muscle relaxants, analgesics (usually fentanyl), hyperventilation, ventilatory rates of greater than 100 breaths/min and low inflating pressures, preventing hypothermia, and correction of acidosis with IV bicarbonate therapy.

9. Accumulating data from animal studies suggest that some anesthetics, opioids, and related drugs (eg, benzodiazepines) may be neurotoxic in the developing brain, and there is some evidence of behavioral changes (eg, learning disabilities) in children who have had multiple anesthetic exposures. However, definitive evidence of neurotoxicity in newborns or children who have had single or limited exposures is lacking and is balanced by concerns about outcomes in newborns who are not anesthetized for painful procedures.

Except for extraordinary circumstances, all newborns require anesthesia for surgery.1-4 In the past, it had been assumed that newborn infants neither experienced nor perceived painful stimuli to the same degree that adults do. Indeed, it was thought that newborns did not have the neurologic substrate necessary for the perception of pain because of a lack of myelinization, incomplete pain pathways from the periphery to the cortex, or immaturity of the cerebral cortex. There is absolutely no evidence that any of ...