Abstract
This chapter provides an in-depth discussion on the complexities associated with the Ex-Utero Intrapartum Therapy; EXIT procedure. The authors provide a thorough analysis of patient and procedural considerations from the maternal and fetal aspects. The perioperative approach for these procedures is reviewed in detail with respect to fetal and maternal anesthetic goals.
A healthy 26-year-old gravida 2 para 1 female was referred for evaluation by her primary obstetrician after an 18-week ultrasound revealed fetal hydrops associated with enlarged lungs and dilated distal trachea. Magnetic resonance imaging (MRI) of the fetus confirmed a diagnosis of laryngeal atresia with no other apparent anomalies, and a diagnosis of congenital high airway obstruction syndrome (CHAOS) was made. A multidisciplinary team consisting of a pediatric surgeon, otolaryngologist, maternal fetal medicine (MFM) specialist, obstetric anesthesiologist, pediatric anesthesiologist, and neonatologist was assembled to review the case. All team members agreed that known laryngeal atresia made successful endotracheal intubation unlikely, and an ex utero intrapartum therapy (EXIT) procedure was deemed the most appropriate approach to delivery.
What Is an EXIT Procedure?
An EXIT procedure is a coordinated surgical procedure performed via cesarean delivery during which fetal oxygenation is maintained by the utero-placental circulation. These procedures are most commonly performed in fetuses with known congenital anomalies that are unlikely to have a successful transition from fetal to neonatal life without medical intervention. Common indications include airway, pulmonary, and cardiac abnormalities. An EXIT-to-airway procedure allows for placental oxygenation to continue while intubation and/or tracheostomy are attempted. An EXIT-to-resection procedure may be performed for pulmonary abnormalities while taking advantage of the ability to operate while on placental support, such as for resection of a congenital pulmonary mass. EXIT-to-ECMO (extracorporeal membrane oxygenation) allows for continued cardiopulmonary support after placental support is discontinued, such as for severe cardiac anomalies. Common indications for each procedure are listed in Table 45.1. Advances in diagnostic and surgical techniques are rapidly expanding the list of indications for EXIT procedures, but the anesthetic principles and considerations remain largely the same.
| Airway/Head and Neck anomalies (EXIT-to-airway) | Large cervical masses (cervical teratomas, cervical lymphangioma, large goiters) Retro-micrognathia/agnathia Congenital high airway obstruction syndrome (CHAOS) |
| Lung or mediastinal masses (EXIT-to-resection) | Congenital cystic adenomatoid malformation (CCAM) Bronchopulmonary sequestration Compressing mediastinal masses |
| Cardiopulmonary conditions EXIT to extracorporeal membrane oxygenation (ECMO) | Severe congenital diaphragmatic hernia Certain types of congenital heart disease |
How Are Patients Selected for an EXIT Procedure?
A mother and fetus are considered appropriate candidates for an EXIT procedure when the risk of extrauterine death or disability to the fetus outweighs the risk of no prenatal intervention, and the risk to the mother is low. These patients should be evaluated by a multidisciplinary team, including pediatric surgeons, MFM specialists, obstetric and pediatric anesthesiologists, and neonatologists. Ideal patients are a mother with an otherwise uncomplicated pregnancy, and a fetus whose indication for surgery is an isolated defect. Relative contraindications include serious maternal comorbidities or the presence of multiple fetal congenital anomalies or a lethal genetic mutation.
What Should the Anesthesiologist’s Preoperative Evaluation Include?
Maternal Preoperative Concerns
A thorough history and physical exam should be performed on the mother with special attention to medical comorbidities, pregnancy-related conditions, past abdominal or gynecologic surgeries, complications with general or neuraxial anesthesia, and information about previous deliveries. The anesthesiologist should be aware of any procedures performed during the pregnancy (e.g., cerclage, amnioreductions), as well as any current medications (e.g., tocolytics, antihypertensives, anticoagulation). Physical examination should focus on the cardiopulmonary system and an assessment of the back in preparation for placement of neuraxial anesthesia.
What Are the Fetal Preoperative Concerns?
For EXIT procedures, the fetus should be as close to term as possible, but some cases such as severe fetal hydrops may require an earlier procedure and delivery. Fetal genetic testing and imaging should be reviewed to ensure there are no contraindications to performing the procedure. The fetal anesthesiologist should be aware of fetal anomalies such as isolated limb abnormalities, as this may affect ease of obtaining IV access. Additionally, discussion with the MFM specialist should include assessment of placental location, fetal presentation, and estimated fetal weight, as these factors can alter the plan for surgical access as well as medication dosing.
The pediatric anesthesiologist’s role perioperatively includes preparation of fetal resuscitation drugs, ensuring adequate fetal monitoring with pulse oximetry, administration of medications (intramuscular or intravenous), evaluating and/or managing the neonate’s airway, as well as overseeing neonatal resuscitation intraoperatively. In cases where surgical intervention is planned immediately after delivery (such as for resection of pulmonary masses), the pediatric anesthesiologist typically transports the neonate to an adjacent operating room to care for the baby during the procedure.
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