Nitroglycerin for fetal surgery: fetoscopy and ex utero intrapartum treatment procedure with malignant hyperthermia precautions

Fetal and Neonatal Anesthesia

Anesthesia for fetal and neonatal surgery requires subspecialized knowledge and expertise. Attention to important anatomic, physiologic, and metabolic differences seen in pregnancy and at birth are essential for the optimal care of these patients. Thorough preoperative evaluations tailored intraoperative strategies and careful postoperative management are critical when devising the anesthetic approach for each of these cases.

Anesthesia for fetal operative procedures: A systematic review

Objective

The anesthetic management of fetal operative procedures (FOP) is a highly debated topic. Literature on fetal pain perception and response to external stimuli is rapidly expanding. Nonetheless, there is no consensus on the fetal consciousness nor on the instruments to measure pain levels. As a result, no guidelines or clinical recommendations on anesthesia modality during FOP are available. This systematic literature review aimed to collect the available knowledge on the most common fetal interventions, and summarize the reported outcomes for each anesthetic approach. Additional aim was to provide an overall evaluation of the most commonly used anesthetic agents.

Methods

Two systematic literature searches were performed in Embase, Medline, Web of Science Core Collection and Cochrane Central Register of Controlled Trials up to December 2021. To best cover the available evidence, one literature search was mostly focused on fetal surgical procedures; while anesthesia during FOP was the main target for the second search. The following fetal procedures were included: fetal transfusion, laser ablation of placental anastomosis, twin-reversed arterial perfusion treatment, fetoscopic endoluminal tracheal occlusion, thoraco-amniotic shunt, vesico-amniotic shunt, myelomeningocele repair, resection of sacrococcygeal teratoma, ligation of amniotic bands, balloon valvuloplasty/septoplasty, ex-utero intrapartum treatment, and ovarian cyst resection/aspiration. Yielded articles were screened against the same inclusion criteria. Studies reporting anesthesia details and procedures’ outcomes were considered. Descriptive statistical analysis was performed and findings were reported in a narrative manner.

Results

The literature searches yielded 1,679 articles, with 429 being selected for full-text evaluation. A total of 168 articles were included. Overall, no significant differences were found among procedures performed under maternal anesthesia or maternal-fetal anesthesia. Procedures requiring invasive fetal manipulation resulted to be more effective when performed under maternal anesthesia only. Based on the available data, a wide range of anesthetic agents are currently deployed and no consistency has been found neither between centers nor procedures.

Conclusions

This systematic review shows great variance in the anesthetic management during FOP. Further studies, systematically reporting intraoperative fetal monitoring and fetal hormonal responses to external stimuli, are necessary to identify the best anesthetic approach. Additional investigations on pain pathways and fetal pain perception are advisable.

Error traps in anesthesia for fetal interventions

A wide range of fetal interventions are being performed worldwide to save the fetus's life, prevent permanent fetal organ damage, and allow a successful transition to extrauterine life. However, these are invasive procedures and can be associated with serious complications. This article focuses on promoting a culture of safety by highlighting five common error traps while anesthetizing patients for fetal interventions. They include failure to preserve uteroplacental perfusion and gas exchange, failure to achieve adequate uterine relaxation prior to hysterotomy, failure to monitor the fetus and prepare for fetal/neonatal resuscitation, failure to prepare for maternal hemorrhage, and failure to promptly treat uterine atony. Practical tips for avoiding these serious complications will also be discussed.

Anesthesia for in utero repair of myelomeningocele

Recently published results suggest that prenatal repair of fetal myelomeningocele is a potentially preferable alternative when compared to postnatal repair. In this article, the pathology of myelomeningocele, unique physiologic considerations, perioperative anesthetic management, and ethical considerations of open fetal surgery for prenatal myelomeningocele repair are discussed. Open fetal surgeries have many unique anesthetic issues such as inducing profound uterine relaxation, vigilance for maternal or fetal blood loss, fetal monitoring, and possible fetal resuscitation. Postoperative management, including the requirement for postoperative tocolysis and maternal analgesia, are also reviewed. The success of intrauterine myelomeningocele repair relies on a well-coordinated multidisciplinary approach. Fetal surgery is an important topic for anesthesiologists to understand, as the number of fetal procedures is likely to increase as new fetal treatment centers are opened across the United States.

Use of fetal analgesia during prenatal surgery

OBJECTIVE

Recent progresses in fetal surgery have raised concern on fetal pain, its long-term consequences and the risks of sudden fetal movements induced by pain. In several studies, surgeons have directly administered opioids to the fetus, while others have considered sufficient the maternally administered analgesics. We performed a review of the literature to assess the state of the art.

METHODS

We performed a PubMed search to retrieve the papers that in the last 10 years reported studies of human fetal surgery and that described whether any fetal analgesia was administered.

RESULTS

We retrieved 34 papers. In three papers, the procedure did not hurt the fetus, being performed on fetal annexes, in two papers, it was performed in the first half of pregnancy, when pain perception is unlikely. In 10 of the 29 remaining papers, fetal surgery was performed using direct fetal analgesia, while in 19, analgesia was administered only to the mother. In most cases, fetal direct analgesia was obtained using i.m. opioids, and muscle relaxant. Rare drawbacks on either fetuses or mothers due to fetal analgesia were reported.

CONCLUSION

Fetal direct analgesia is performed only in a minority of cases and no study gives details about fetal reactions to pain. More research is needed to assess or exclude its possible long-term drawbacks, as well as the actual consequences of pain during surgery.

The new challenging pediatric patient

The 'new' challenging pediatric patients are those who could be called 'the survivors' and neonates undergoing birth under materno-fetal circulation. Their anesthetic management is complex because their initial pathology was previously lethal: the physiologic, pharmacologic, and or technical aspect of their management is presently unknown or hypothetical. Some examples are described. Communication with the pediatrician in charge of the child is the key to safe and effective anesthetic care of these cases.

Open fetal surgery for myelomeningocele

In a recently completed randomized, prospective clinical trial, fetal repair for myelomeningocele was shown to result in reduced rates of hydrocephalus requiring placement of a ventriculoperitoneal shunt, improvement in Chiari malformation Type II, and improvement in neurological function compared with standard postnatal repair. Successful fetal surgery requires the active participation and interaction of several clinical teams. Each group has a specific role, and overlap is often required at different points of the treatment plan. Extensive multispecialty discussions with the patient and family are necessary before informed consent can be obtained. Fetal surgery carries significant risks to the mother and fetus and these must be carefully considered prior to a final treatment decision. This review will summarize the evaluation and treatment of patients undergoing fetal repair for myelomeningocele at one institution.

Update in fetal anesthesia for the ex utero intrapartum treatment (EXIT) procedure

The ex-utero intrapartum treatment (EXIT) is one type of fetal surgery, performed before delivery while the fetus remains attached to the uteroplacental circulation. This intervention improves neonatal morbidity and mortality of certain congenital diseases. For instance, securing the airway of a fetus with congenital airway obstruction while on uteroplacental circulation prevents the hypoxemia during the establishment of an airway post-delivery. Anesthesia for fetal surgery now incorporates new knowledge of the maternal/fetal response to anesthetic agents. This chapter reviews for the EXIT procedure the effects of maternal anesthesia on fetal hemodynamics, intravenous anesthesia to supplement inhalational anesthesia in order to provide maternal-fetal hemodynamic stability during surgery, intraoperative fetal monitoring, maternal pharmacokinetics approach to study placental drug transfer and fetal pharmacokinetics to improve our understanding of the effects of maternal anesthesia on the fetus.

Ex utero intrapartum treatment procedure in a patient with arthrogryposis multiplex congenita, using continuous spinal anesthesia and intravenous nitroglycerin for uterine relaxation

The ex utero intrapartum treatment procedure allows for the controlled management of a potentially life-threatening difficult airway in the newborn. General anesthesia has previously been reported for the management of this procedure. We report the use of continuous spinal anesthesia in conjunction with intravenous nitroglycerin for the ex utero intrapartum treatment procedure in a woman with arthrogryposis multiplex congenita, a rare syndrome characterized by rigid joints and limb contractures.

Four cases of congenital airway obstruction: optimising perinatal management

Congenital anomalies causing airway obstruction in the newborn are potentially fatal. However if an effective airway can be maintained the long-term prognosis is often excellent. We present four cases of airway obstruction, three of which were diagnosed antenatally. We discuss the role of antenatal imaging and review delivery options including the need for a multidisciplinary team approach. In conclusion, we recommend antenatal imaging with both ultrasound scan and magnetic resonance to inform perinatal management. Polyhydramnios, in association with suspected neonatal airway obstruction, should alert clinicians to a high-risk situation. We recognize that even in skilled hands, securing an airway can be very difficult and alternatives such as maintenance of the fetomaternal circulation or extra-corporeal life support should be considered.

Case series: Combined spinal epidural anesthesia for Cesarean delivery and ex utero intrapartum treatment procedure

PURPOSE

To report the use of regional anesthesia and iv nitroglycerin to provide anesthesia and uterine relaxation for three Cesarean deliveries (CD) involving ex utero intrapartum treatment (EXIT) of potentially life-threatening airway obstruction in the newborn.

CLINICAL FEATURES

Case 1--a 36-yr-old woman at 38 weeks' gestation was scheduled for an elective CD for fetal skeletal dysplasia and micrognathia. Case 2--a 34-yr-old woman at 35 weeks gestation had a fetal ultrasound revealing fixed neck flexion and micrognathia consistent with fetal arthrogryposis. Case 3--a 27-yr-old woman presented at 38 weeks gestation for CD for severe fetal micrognathia, with mandibular growth below the fifth percentile. For each case, a combined spinal epidural anesthetic was performed with 0.75% bupivacaine, fentanyl and morphine intrathecally followed by placement of a multiorifice epidural catheter. Prior to uterine incision patients received a loading dose followed by an iv infusion of nitroglycerin. Uterine relaxation was sufficient in all cases for delivery of the fetus, and allowed for evaluation by direct laryngoscopy and intubation while maintaining fetal-placental circulation. The surgical procedures were completed without incident.

CONCLUSIONS

Anesthesia and uterine relaxation for CD and EXIT procedures can be safely provided with regional anesthesia and iv nitroglycerin.

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 endoscopic surgery: indications and anaesthetic management

Fetal intervention for certain life-threatening conditions has progressed from being primarily experimental in nature to the standard of care in certain circumstances. While surgical techniques have advanced over the past few years, the anaesthetic goals for these interventions have remained the same; namely, minimizing maternal and fetal risk as well as maximizing the chances of a successful fetal intervention and optimize the conditions necessary to carry the fetus to term gestation. Fetal endoscopic techniques allow access to the fetus without the need for a hysterotomy incision, thus improving the chances of controlled post-operative tocolysis and term gestation after fetal intervention. This procedure, however, is not without associated risks to both fetus and mother. This chapter will address the fetal diseases that may benefit from fetoscopic intervention, the rationale behind why maternal and fetal anaesthesia is required, the various anaesthetics used for these cases and specific considerations of both maternal and fetal physiology that aid in the determination of the best anaesthetic technique for individual cases. Methods of intra-operative fetal monitoring and fetal resuscitation will also be discussed.