Objective: To lower the incidence and severity of fetal cardiovascular depression during maternal fetal surgery under general anesthesia.
Aim: We hypothesized that supplemental intravenous anesthesia (SIVA) with propofol and remifentanil would lower the need for high-dose inhalational anesthesia and provide adequate maternal depth of anesthesia and uterine relaxation. SIVA technique would minimize prolonged fetal exposure to deep inhalational anesthetics and significant intraoperative fetal cardiovascular depression.
Background: Fetal hypoxia and significant fetal hemodynamic changes occur during open fetal surgery because of the challenges such as surgical manipulation, hysterotomy, uterine contractions, and effects of anesthetic drugs. Tocolysis, a vital component of fetal surgery, is usually achieved using volatile anesthetic agents. High concentrations of volatile agents required to provide an appropriate degree of uterine relaxation may cause maternal hypotension and placental hypoperfusion, as well as direct fetal cardiovascular depression.
Methods: We reviewed medical records of 39 patients who presented for ex utero intrapartum treatment and mid-gestation open fetal surgery between April 2004 and March 2009. Out of 39 patients, three were excluded because of the lack of echocardiographic data; 18 patients received high-concentration desflurane anesthesia and 18 patients had SIVA with desflurane for uterine relaxation. We analyzed the following data: demographics, fetal medical condition, anesthetic drugs, concentration and duration of desflurane, maternal arterial blood pressure, intraoperative fetal echocardiogram, presence of fetal bradycardia, and need for intraoperative fetal resuscitation.
Results: Adequate uterine relaxation was achieved with about 1.5 MAC of desflurane in the SIVA group compared to about 2.5 MAC in the desflurane only anesthesia group (P = 0.0001). More fetuses in the high-dose desflurane group compared to the SIVA group developed moderate-severe left ventricular systolic dysfunction over time intraoperatively (P = 0.02). 61% of fetuses in the high-dose desflurane group received fetal resuscitative interventions compared to 26% of fetuses in the SIVA group (P = 0.0489).
Conclusion: SIVA as described provides adequate maternal anesthesia and uterine relaxation, and it allows for decreased use of desflurane during open fetal surgery. Decreased use of desflurane may better preserve fetal cardiac function.