There has been growing concern about the detrimental effects of certain anesthetic agents on the developing brain. Preclinical studies in small animal models as well as nonhuman primates suggested loss or death of brain cells and consequent impaired neurocognitive function following anesthetic exposure in neonates and late gestation fetuses. Human studies in this area are limited and currently inconclusive. On Dec. 14, 2016, the US Food and Drug Administration issued a warning regarding impaired brain development in children following exposure to certain anesthetic agents used for general anesthesia, namely the inhalational anesthetics isoflurane, sevoflurane, and desflurane, and the intravenous agents propofol and midazolam, in the third trimester of pregnancy. Furthermore, this warning recommends that health care professionals should balance the benefits of appropriate anesthesia in young children and pregnant women against potential risks, especially for procedures that may last >3 hours or if multiple procedures are required in children <3 years old. The objective of this article is to highlight how the Food and Drug Administration warning may impact the anesthetic and surgical management of the obstetric patient. Neuraxial anesthesia (epidural or spinal anesthesia) is more commonly administered for cesarean delivery than general anesthesia. The short duration of fetal exposure to general anesthesia during cesarean delivery has not been associated with learning disabilities. However, the fetus can also be exposed to both intravenous and inhalation anesthetics during nonobstetric or fetal surgery in the second and third trimester; this exposure is typically longer than that for cesarean delivery. Very few studies address the effect of anesthetic exposure on the fetus in the second trimester when most nonobstetric and fetal surgical procedures are performed. It is also unclear how the plasticity of the fetal brain at this stage of development will modulate the consequences of anesthetic exposure. Strategies that may circumvent possible untoward long-term neurologic effects of anesthesia in the baby include: (1) use of nonimplicated (nongamma-aminobutyric acid agonist) agents for sedation such as opioids (remifentanil, fentanyl) or the alpha-2 agonist, dexmedetomidine, when appropriate; (2) minimizing the duration of exposure to inhalational anesthetics for fetal, obstetric, and nonobstetric procedures in the pregnant patient, as much as possible within safe limits; and (3) commencing surgery promptly and limiting the interval between induction of anesthesia and surgery start time will help decrease patient exposure to inhalational agents. While the Food and Drug Administration warning was based on duration and repetitive nature of exposure rather than concentration of inhalational agents, intravenous tocolytics can be considered for intraoperative use, to provide uterine relaxation for fetal surgery, in lieu of high concentrations of inhalational anesthetic agents. Practitioners should consider the type of anesthesia that will be administered and the potential risks when scheduling patients for nonobstetric and fetal surgery.
Keywords: Food and Drug Administration; anesthesia; brain; cesarean delivery; desflurane; development; fetal surgery; fetus; general anesthesia; inhalation anesthesia; isoflurane; midazolam; propofol; sedatives; sevoflurane.
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