The Cesarean Delivery of a Twin Gestation Under 2 Minimum Alveolar Anesthetic Concentration Isoflurane

Anesthésie maternofœtale pour « ex utero intrapartum » traitement (EXIT) procédure : à propos de deux cas

The ex utero intrapartum treatment (EXIT) procedure is a surgical procedure maintaining utero-placental circulation during caesarean section. Anaesthetic implications are described: foetal transplacental anaesthesia to avoid first breathing and to permit surgical procedure on obstructed foetal airway, deep maternal haemodynamically stable anaesthesia to relax uterine smooth muscle during a long caesarean procedure but avoiding post-partum haemorrhage. Volatile anaesthesia with sevoflurane seems to be adequate for these aims. Two cases are described.

Die EXIT-Prozedur als anästhesiologische Herausforderung

The ex-utero intra-partum (EXIT) procedure enables the surgeon to perform invasive procedures in an infant during cesarean section before clamping the umbilical cord. Specific anesthesiological concepts are necessary for ensuring sufficient umbilical perfusion. We report the case of a 33-year-old female undergoing cesarean section in the 36th week of pregnancy because of a large fetal cervical tumor. The EXIT procedure was performed in order to secure the infant's airway during delivery. The anesthesiological management and interdisciplinary tasks are discussed in the literature review.

Ex utero intrapartum surgery (EXIT): indications and anaesthetic management

The ex utero intrapartum treatment (EXIT) procedure is a technique for safely managing airway obstruction at birth, in which placental support is maintained until the airway is evaluated and secured. In addition to the usual considerations of anaesthesia in obstetrics there are special considerations relating to the EXIT procedure: maintaining fetoplacental circulation by profound uterine relaxation and achieving fetal anaesthesia for airway manipulations. This chapter focuses on the key issues involved in managing this procedure: the indications, preoperative concerns, organization of a multidisciplinary team, problems of maternal and fetal anaesthesia, maintenance of the uterine relaxation and control of fetal airway.

Fetal surgery, anaesthesiological considerations

PURPOSE OF REVIEW

Refined techniques and skills have enabled sophisticated prenatal diagnosis in utero and resulted in the newly evolving specialty of fetal surgery in a few centres worldwide. Most of the procedures performed today have been preceded by extensive experimental research in animals, whereas fetal anaesthesia is mainly based on clinical experience and a few studies performed in pregnant sheep.

RECENT FINDINGS

Major limitations of fetal surgery include the high frequency of preterm labour and delivery which may offset any fetal benefit of the surgical procedure. The development of more potent tocolytic drugs than the drugs currently available may thus be compared to the meaning of potent immunosuppressive agents in organ transplantation. Fetal mortality and maternal morbidity consequently lead to a more cautious way of treatment, as with the development of endoscopic fetal surgery.

SUMMARY

The invasive fetal surgery is still considered as being in a research stage in most cases. Therefore most procedures are performed as minimally invasive, avoiding substantial risks by accessing the uterus through minimal openings. Some new devices are under investigation for monitoring the myometrial electrical activity and mechanical contractility and the fetal electroencephalogram, the continuous monitoring of the fetal arterial oxygen saturation, PO2 and PCO2, and for monitoring fetal cerebral oxygenation, blood volume and blood flow by near infrared spectroscopy.

Anesthesia for fetal surgery

Fetal surgery is a rapidly growing and evolving area. Fetal surgery is based on years of animal and clinical research. In contrast, anesthesia techniques for fetal surgery are based on clinical experience. The techniques that have emerged are safe for mother and fetus. In this review, the authors describe current techniques for anesthetic management of fetal surgery patients. General anesthesia is the primary technique used for hysterotomy based surgical correction of midgestation fetuses and ex utero interpartum corrections of end-gestation fetuses. Epidural analgesia, with general anesthesia as back-up, is the primary technique used for fetoscopic cases in which anesthetic care is required. Because of the myriad of anesthetic and surgical issues these cases generate, it is essential to have good communication and cooperation between surgeons and anesthesiologists from the preoperative period to the postoperative period. This will allow development of a cohesive anesthetic and surgical plan that can be used for the safe perioperative management of the fetal surgery patient.

Ex utero intrapartum therapy

The hallmark of ex utero intrapartum therapy (EXIT) procedure is the maintenance of uteroplacental blood flow and gas exchange. This goal is achieved with the use of inhalational agents to relax uterine tone, a continuous amnioinfusion to stabilize uterine volume, and partial exposure of the fetus. From March 1996 to December 2002, 43 EXIT procedures were performed at the Children's Hospital of Philadelphia (CHOP). Indications included airway obstruction from fetal neck masses (n = 19), reversal of tracheal occlusion for congenital diaphragmatic hernia (CDH; n = 13), resection of massive congenital cystic adenomatoid malformation of the lung (n = 5), congenital high airway obstruction syndrome (n = 3), EXIT-to-extracorporeal membrane oxygenation for a fetus with CDH and a cardiac defect (n = 1), unilateral pulmonary agenesis (n = 1), and thoracoomphalopagus conjoined twins (n = 1). Eight fetuses required initial tracheotomy at the time of EXIT to secure the airway. One death occurred during the EXIT procedure secondary to inability to secure the airway with parental refusal for tracheotomy. In all cases, the EXIT procedure provided time on uteroplacental gas exchange to perform procedures such as direct laryngoscopy, bronchoscopy, tracheotomy, arterial and venous access, resection of neck or lung masses, and ECMO cannulation, thereby converting an emergent crisis into a controlled situation.

Airway management on placental support (AMPS)--the anaesthetic perspective

Neonatal airway obstruction has been reported to have a high mortality. Antenatal diagnosis of this condition is now possible. Anaesthetic and surgical techniques have been developed that allow neonatal airway obstruction to be managed at delivery, while the fetus remains oxygenated via the placental circulation. Three case studies are presented, and the anaesthetic issues for mother and fetus/neonate are discussed with reference to previously published cases of airway management on placental support. In particular, techniques for uterine relaxation and maintenance of placental circulation are explored. The history of these procedures and issues of planning and logistics are also discussed.

Anesthetic management of the exit (ex utero intrapartum treatment) procedure

The EXIT (ex utero intrapartum treatment) procedure is used to maintain fetal-placental circulation during partial delivery of a fetus with a potentially life-threatening upper airway obstruction. We performed the EXIT procedure on a fetus with a large intra-oral cyst. Sevoflurane was used as the anesthetic because of its rapid titratability. Sevoflurane provided excellent maternal and fetal anesthesia. Modifications to previously described monitoring techniques for the EXIT procedure were also used.

Anesthesia for fetoscopic fetal surgery: twin reverse arterial perfusion sequence and twin-twin transfusions syndrome

IMPLICATIONS

Twin reversed arterial perfusion sequence and twin-twin transfusion syndrome can be managed by fetoscopic fetal surgery. It is important to consider the fetal, uteroplacental, and maternal issues when choosing an anesthetic technique. We report on three patients with differing anesthetic issues using fetoscopic surgery for umbilical cord coagulation.

Anesthetic considerations for fetal surgery

This article outlines the perioperative management of the parturient who presents for fetal surgery. Anesthetic considerations include the physiological changes of pregnancy, preterm labor, the consequences of tocolytic drugs, maternal and fetal anesthesia, and postoperative analgesia.