Prolonged general anesthesia for experimental craniofacial surgery in fetal swine.

A protocol utilizing high preoperative doses of altrenogest (Regu-Mate) and a "balanced" general anesthesia regimen consisting of isoflurane at subanesthetic doses supplemented with intravenous doses of sodium thiopental was developed to prevent preterm labor, minimize intracranial fetal cerebral edema, and decrease postpartum mortality of fetal swine after undergoing complex in utero craniofacial procedures. A total of 20 fetal piglets at 75% gestation were exposed to prolonged (> 3 h) anesthesia conditions of which 7 piglets were randomly selected to undergo experimental craniofacial procedures consisting of periosteal stripping of frontal and parietal bone segments with/without extensive coronal suture fusion procedures. Neither sows nor piglets were lost to anesthetic complications during the initial laparotomy or subsequent cesarean delivery. None of the sows experienced uterine sepsis or underwent preterm labor. The overall survival rate for all piglets exposed to prolonged anesthesia conditions was 95% at 4 weeks and 45% at 11 weeks after surgery. The experimental group's survival was 85.7% at 4 weeks and 28.5% at 11 weeks after surgery.