Anesthesia for fetal operative procedures: A systematic review

An Evidence-Based Discussion of Fetal Pain and Stress

BACKGROUND

The concept of fetal pain results from procedures conducted without anesthesia in preterm newborns and fetuses, which indicate that it is possible to examine fetal pain based on stress hormone, metabolic, and behavioral changes. Anatomical and physiological data suggest that fetuses become capable of processing nociceptive stimuli around midgestation, although the associated changes in fetal brain development remain unclear. What constitutes fetal pain remains controversial in the light of the definition of pain adopted by the International Association for the Study of Pain (IASP), which posits pain as an "unpleasant sensory and emotional experience."

SUMMARY

Here, we examine the notion that human fetuses cannot "experience" pain and potential implications of this claim. We highlight the key scientific evidence related to fetal pain, including clinical studies on pain in fetuses and preterm newborns. We argue that consistent patterns of stress hormones, metabolic changes, body movements, hemodynamic changes, and pain-related facial expressions in fetuses exposed to invasive procedures overcome the need for subjective proof of pain as articulated in the IASP definition. No study to date has conclusively proven the absence of fetal pain beyond the age of viability.

KEY MESSAGES

Based on the current evidence, we propose that all fetuses receive anesthesia regardless of the invasive procedures being performed to guarantee the least possible pain and physiological, behavioral, or hormonal responses without exposing the mother or her baby to unnecessary complications.

Transferring an extremely premature infant to an extra-uterine life support system: a prospective view on the obstetric procedure

To improve care for extremely premature infants, the development of an extrauterine environment for newborn development is being researched, known as Artificial Placenta and Artificial Womb (APAW) technology. APAW facilitates extended development in a liquid-filled incubator with oxygen and nutrient supply through an oxygenator connected to the umbilical vessels. This setup is intended to provide the optimal environment for further development, allowing further lung maturation by delaying gas exposure to oxygen. This innovative treatment necessitates interventions in obstetric procedures to transfer an infant from the native to an artificial womb, while preventing fetal-to-neonatal transition. In this narrative review we analyze relevant fetal physiology literature, provide an overview of insights from APAW studies, and identify considerations for the obstetric procedure from the native uterus to an APAW system. Lastly, this review provides suggestions to improve sterility, fetal and maternal well-being, and the prevention of neonatal transition.

Anesthetic management of fetal pulmonary valvuloplasty: A case report

Anesthesia management of fetal pulmonary valvuloplasty (FPV) is difficult, requiring careful consideration of both the mother and the fetus. Few reports have been published on specific anesthesia implementation and intraoperative management. We report the case of a pregnant woman who was treated with FPV under combined spinal epidural anesthesia (CSEA) with dexmedetomidine in the second trimester of pregnancy. Meanwhile, the application of fetal anesthesia through the umbilical vein was optimal. During the operation, the vital signs of the pregnant woman were stable with no complications and the fetal bradycardia was corrected by intracardiac injection of epinephrine. Four months postoperatively, a boy was born alive by full-term transvaginal delivery. CSEA may be a suitable anesthesia method for FPV surgery. Nevertheless, maternal hemodynamic stability maintenance, effective fetal anesthesia, and timely fetal resuscitation were necessary.

Decreased Maternal Morbidity and Improved Perinatal Results of Magnesium-Free Tocolysis and Classical Hysterotomy in Fetal Open Surgery for Myelomeningocele Repair: A Single-Center Study

Fetal and maternal risks associated with open fetal surgery (OFS) in the management of meningomyelocele (MMC) are considerable and necessitate improvement. A modified technique of hysterotomy (without a uterine stapler) and magnesium-free tocolysis (with Sevoflurane as the only uterine muscle relaxant) was implemented in our new magnesium-free tocolysis and classical hysterotomy (MgFTCH) protocol. The aim of the study was to assess the introduction of the MgFTCH protocol in reducing maternal and fetal complications. The prospective study cohort (SC) included 64 OFS performed with MgFTCH at the Fetal Surgery Centre Bytom (FSCB) (2015-2020). Fetal and maternal outcomes were compared with the retrospective cohort (RC; n = 46), and data from the Zurich Center for Fetal Diagnosis and Therapy (ZCFDT; n = 40) and the Children's Hospital of Philadelphia (CHOP; n = 100), all using traditional tocolysis. The analysis included five major perinatal complications (Clavien-Dindo classification, C-Dc) which developed before the end of 34 weeks of gestation (GA, gestational age). None of the newborns was delivered before 30 GA. Only two women presented with grade 3 complications and none with 4th or 5th grade (C-Dc). The incidence of perinatal death (3.3%) was comparable with the RC (4.3%) and CHOP data (6.1%). MgFTCH lowers the risk of major maternal and fetal complications.

The fetal pain paradox

Controversy exists as to when conscious pain perception in the fetus may begin. According to the hypothesis of cortical necessity, thalamocortical connections, which do not form until after 24-28 weeks gestation, are necessary for conscious pain perception. However, anesthesiologists and neonatologists treat age-matched neonates as both conscious and pain-capable due to observable and measurable behavioral, hormonal, and physiologic indicators of pain. In preterm infants, these multimodal indicators of pain are uncontroversial, and their presence, despite occurring prior to functional thalamocortical connections, has guided the use of analgesics in neonatology and fetal surgery for decades. However, some medical groups state that below 24 weeks gestation, there is no pain capacity. Thus, a paradox exists in the disparate acknowledgment of pain capability in overlapping patient populations. Brain networks vary by age. During the first and second trimesters, the cortical subplate, a unique structure that is present only during fetal and early neonatal development, forms the first cortical network. In the third trimester, the cortical plate assumes this function. According to the subplate modulation hypothesis, a network of connections to the subplate and subcortical structures is sufficient to facilitate conscious pain perception in the fetus and the preterm neonate prior to 24 weeks gestation. Therefore, similar to other fetal and neonatal systems that have a transitional phase (i.e., circulatory system), there is now strong evidence for transitional developmental phases of fetal and neonatal pain circuitry.

Evaluation and Treatment of Pain in Fetuses, Neonates and Children

The perception of pain is individual and differs between children and adults. The structures required to feel pain are developed at 24 weeks of gestation. However, pain assessment is complicated, especially in neonates, infants and preschool-age children. Clinical scales adapted to age are the most used methods for assessing and monitoring the degree of pain in children. They evaluate several behavioral and/or physiological parameters related to pain. Some monitors detect the physiological changes that occur in association with painful stimuli, but they do not yet have a clear clinical use. Multimodal analgesia is recommended for pain treatment with non-pharmacological and pharmacological interventions. It is necessary to establish pharmacotherapeutic protocols for analgesia adjusted to the acute or chronic, type and intensity of pain, as well as age. The most used analgesics in children are paracetamol, ibuprofen, dipyrone, opioids (morphine and fentanyl) and local anesthetics. Patient-controlled analgesia is an adequate alternative for adolescent and older children in specific situations, such as after surgery. In patients with severe or persistent pain, it is very important to consult with specific pain services.