Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Obstetric Anesthesia
Surgery to correct fetal anomalies during gestation remains in the investigational stage. The anesthetic approach to these patients must consider maternal safety, tocolysis, and fetal anesthesia. A technique involving greater than one MAC of isoflurane in 100% oxygen is presented. Isoflurane provides uterine relaxation , maternal anesthesia , and fetal anesthesia .
After IRB approval, the charts of parturients who underwent surgery to correct fetal anomalies were reviewed. Gestational age of the fetus, the time from induction to extubation, the time from uterine incision to closure, the estimated blood loss, the amount of ephedrine administered, the highest end-tidal concentration of isoflurane, and the intraoperative fetal oxygenation were recorded. The anesthetic technique consisted of rapid sequence induction with thiopental and succinylcholine; maintenance consisted of isoflurane in oxygen. Maternal arterial pressure was maintained with ephedrine.
Seven parturients underwent fetal surgery. The anomalies were: 2 diaphragmatic hernias, 2 cystic adenoid malformation of the lung, 1 sacrococcygeal teratoma, and 2 twin-twin transfusions. Mean +/- standard deviation is presented. (Table 1)
No fetus required supplemental narcotics or muscle relaxants for movement.
Greater than 1 MAC of isoflurane in 100% oxygen was well tolerated by the mother. Blood loss was not excessive. Ephedrine was required to maintain maternal blood pressure at baseline. Uterine relaxation and fetal anesthesia were achieved. This is the first report of oxygen saturation in a 22-24 week fetus. Despite the high concentration of isoflurane, oxygenation was maintained in the fetus. Although fetal blood pressure was not directly measured, a fetal pulse oximetry reading was able to be obtained, suggesting adequate perfusion pressure. The use of greater than 1 MAC isoflurane for surgery during pregnancy is well tolerated by the mother and fetus.
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