Patient Education and Consent
Before being offered fetal wire tracheoplasty or an ex-utero intrapartum treatment (EXIT) delivery for congenital high airway obstruction syndrome (CHAOS), patients should be counseled regarding the particular upper airway malformation and possible outcomes. Discussing the possibility of permanent tracheostomy and lifelong speech impairment is essential. From a maternal standpoint, depending on placental location, a classic hysterotomy may be required, prohibiting the possibility of future vaginal deliveries.
Patient Preparation
Anesthesia
Inhaled anesthetics, particularly isoflurane [20, 21] , are necessary for uterine relaxation and uteroplacental gas exchange, which has been demonstrated to be normal up to 54 minutes on uteroplacental support during EXIT delivery. [22]
Alpha-adrenergic agonists are frequently required to maintain the maternal blood pressure; high levels of isoflurane, needed for uterine relaxation, can cause hypotension. Additionally, nitroglycerin may help with uterine relaxation; activation of guanylyl cyclase leads to increased levels of cyclic guanosine monophosphate (cGMP) and decreased levels of intracellular calcium, thereby causing the uterus to relax. Typically, a fetal cocktail consisting of a paralytic and narcotic agent is administered directly into the fetus via an intramuscular injection.
Positioning
The patient is typically placed in the supine position on the operating room table. Occasionally, the patient may be placed in lithotomy position to increase available space for operating room staff.
Monitoring & Follow-up
Because fetal intervention increases the risk of preterm premature rupture of the membrane and preterm delivery, patients must be monitored closely following a fetal wire tracheoplasty, and any changes in fetal movement or maternal complications should prompt immediate evaluation.
During EXIT deliveries, given the propensity for bleeding, the maternal hematocrit is measured preoperatively and postoperatively; prior to incision, 4 units of typed and crossed blood is prepared.
After birth, follow-up computed tomography (CT) or magnetic resonance imaging (MRI) is commonly performed to confirm the diagnosis, to delineate anatomy, and to screen for tracheoesophageal fistula (TEF). Surgical management can be elective once an airway is established and a TEF is ruled out.
Bronchoscopy should be performed during the neonatal period; laryngeal obstructions frequently result from laryngeal cysts or webs and can occasionally be resected or ablated endoscopically.
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EXIT procedure with fetus maintained on uteroplacental circulation
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Intubation during EXIT procedure
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Tracheostomy performed during EXIT procedure for difficulty obtaining an oral airway
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Fetoscopic approach for in utero tracheoplasty
