Effective evaluation, preparation, and anesthetic management of neonates depend on appropriate knowledge, clinical skills, and vigilance by the anesthesiologist. The anesthesiologist needs to develop a detailed plan that encompasses the issues of anesthetic equipment and monitoring, airway management, drug choice, fluid management, temperature control, anticipated surgical needs, pain management, and postoperative care.

1. Preoperative Considerations
   1. Preanesthetic Evaluation: History. The preanesthetic planning process starts with an evaluation of the course of intrauterine growth followed by labor and delivery and the immediate postpartum course.
      1. The World Health Organization definition of prematurity is <37 weeks' gestation at birth. The greater the degree of prematurity, the more physiologic abnormalities will be expected (variability of responsiveness to anesthetic agents, fluids, cardioactive drugs, and stress of the surgical procedure) (Table 41-4: Abnormalities Associated with the Preterm Infant: Common Anesthetic Concerns).
      2. Low birth weight is defined as a birth weight of ≤2500 g.
   2. Preanesthetic Evaluation: Physical Examination. Physical examination of newborns is focused by the condition requiring surgical intervention.
      1. If there are clinical signs of dehydration, efforts should be made to correct the deficits before surgery except in extreme, life-threatening situations.
      2. Physical examination also focuses on the respiratory and cardiovascular systems.
   3. Preanesthetic Evaluation: Laboratory Tests
      1. Most newborns should have a blood count and glucose level drawn.
      2. Electrolyte determinations and coagulation profiles are indicated in specific patients. Unexplained hypotension, irritability, or seizures can be presenting signs of hypocalcemia.
   4. Preanesthetic Plan (Table 41-5: Major Factors to Consider in Planning the Anesthesia for Neonate)
   5. Premedication is not commonly used for neonatal anesthetics. (Atropine may be used because of the dominance of the parasympathetic nervous system and bradycardia on induction or in response to inhalational agents.)
2. Intraoperative Considerations
   1. Monitoring. Neonatal patients are at a disadvantage when it comes to perioperative monitoring because of their small size. Pulse oximetry is one of the most important monitors in neonatal anesthesia. Electrocardiography is useful primarily to assess heart rate and rhythm. Blood pressure measurements are important in the management of all newborns. An effective alternative to a conventional blood pressure cuff is to use a manual cuff and place a Doppler probe over the brachial or radial artery. Ultrasound guidance is often used when central venous monitoring is indicated in neonatal surgery.
   2. Anesthetic Systems. There is a long tradition in pediatric anesthesia of using semi-open, nonrebreathing systems for general anesthesia in newborns (Jackson-Rees adaptation of the Ayre's T-piece, Bain circuit). As the use of these circuits has diminished, familiarity with their use and application has decreased in favor of the semi-closed rebreathing circle systems used in adult patients.
   3. Induction of Anesthesia. There is no one method of induction and maintenance of anesthesia that is best for all patients.
   4. Airway Management. Most newborns' tracheas are intubated after a rapid sequence induction. A Miller #1 blade is commonly used for full-term newborns and a Miller #0 in preterm newborns. Uncuffed tubes have traditionally been used in newborns to minimize cuff pressure on the subglottic larynx, especially at the level of the cricoid. It is prudent to use the depth markers at the end of the tube to ensure under direct vision that the tip is advanced 2 or 3 cm past the vocal cords.
   5. Anesthetic Dose Requirements of Neonates. Neonates and premature infants have lower anesthetic requirements than older infants and children. The reasons for the lower minimum alveolar concentration (MAC) requirements are believed to be an immature nervous system, progesterone from the mother and elevated blood levels of endorphins coupled with an immature blood–brain barrier.
   6. Regional Anesthesia (Table 41-6: Regional Anesthesia Techniques that are Useful in Neonates)
3. Postoperative Pain Management (Table 41-7: Postoperative Pain Management for Neonates and Infants)
4. Postoperative Ventilation
   1. If the surgical procedure or the neonate's condition is such that postoperative ventilation is likely, the prolonged respiratory effects of opioids or any other drug are of little concern.
   2. If the surgical procedure will be relatively short and by itself does not require postoperative ventilation, the clinician should carefully select drugs, as well as doses of anesthetic drugs and relaxants, that will not necessitate prolonged postoperative ventilation or intubation.
   3. Postoperative ventilation places the neonate at added risk because of the problems associated with mechanical ventilation, trauma to the subglottic area, and potential development of postoperative subglottic stenosis or edema.

Neonatal Anesthesia

1. Physiology of the Infant and the Transition Period
2. Anatomy of the Neonatal Airway
3. Anesthetic Drugs in Neonates
4. Anesthetic Management of the Neonate
5. Special Considerations
6. Surgical Procedures in Neonates