General anesthesia for surgical repair of intracranial aneurysm in pregnancy: effects on fetal heart rate.

A 30-year-old nulliparous woman underwent surgery for a ruptured aneurysm of the left vertebral artery in gestational week 27. The fetal heart rate (FHR) was monitored continuously with an abdominal Doppler transducer. Anesthesia was induced with midazolam, fentanyl, and thiopental and maintained with fentanyl, isoflurane, and nitrous oxide 67% in oxygen. Surgery was performed under moderate hypotension (mean arterial pressure +/- 70 mmHg) and moderate hyperventilation (arterial carbon dioxide pressure +/- 33 mmHg). There was a complete disappearance of FHR variability without decelerations or bradycardia. In the night following surgery, the patient was sedated with large parenteral doses of midazolam and fentanyl. Despite this sedation, some FHR variability reappeared within 40 minutes after discontinuation of the inhalation anesthetics. After discontinuation of parenteral midazolam and fentanyl, normal FHR variability returned within 60 minutes. In week 41 of pregnancy, a healthy girl of 4015 gm was born.