Fetal pain perception and pain management

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.

Fetal surgery has no additional effect to general anesthesia on brain development in neonatal rabbits

BACKGROUND

Fetal surgery is part of modern fetal medicine, and some procedures, such as fetal spina bifida repair, are performed under general anesthesia. Fetuses are operated on in a time window when the developing brain is extremely vulnerable to external, potentially harmful factors. To date, little is known about the effect of fetal surgery on fetal brain development.

OBJECTIVE

This study aimed to assess the effect of fetal surgery on the developing fetal brain in the rabbit model.

STUDY DESIGN

This was a randomized, sham-controlled study in time-mated pregnant does at 28 days' gestation (term, 31 days), which corresponds to the start of the peak of brain development and end of the second trimester of pregnancy in humans. We included 4 different groups in this experiment: no-surgery, general anesthesia, general anesthesia+hysterotomy, and general anesthesia+fetal surgery. In 11 does, anesthesia was induced using propofol and maintained for 75 minutes with 3.6 vol% (4% is the equivalent of 1 minimum alveolar concentration) sevoflurane. Maternal blood pressure, heart rate, oxygen saturation, temperature, end-tidal CO2 were continuously monitored. For each operated doe, 6 fetuses were part of the experiment. Randomization determined which cornual sac and what opposing third sac were assigned to fetal surgery: hysterotomy, fetal injection (atropine, fentanyl, and cisatracurium), fetal skin incision, and suturing. Only hysterotomy was performed on the opposing cornual and third amniotic sacs of the does. The fetus in these experimental sacs was used as internal unmanipulated control (general anesthesia). All fetuses (n=38) from unmanipulated does (n=4) served as external controls (no-surgery). At term, the does were delivered by cesarean delivery under ketamine-medetomidine sedation and local anesthesia. The pups underwent standardized motoric and sensory neurologic testing on day 1 followed by euthanasia and brain harvesting for histologic assessment of neurons, synapses, proliferation, and glial cells.

RESULTS

Maternal vital signs were stable during surgery. Survival was similar in the 4 groups (75%-94%), and brain-to-body weight ratio was comparable; only the no-surgery pups had a higher brain weight. On postnatal day 1, the pups in the 4 groups had a comparable neurobehavioral outcome on both motoric and sensory testing. In the prefrontal cortex, no-surgery pups had significantly higher neuron density than pups who underwent maternal surgery, but there was no difference among pups that underwent general anesthesia, hysterotomy, or fetal surgery. The measurements of proliferation had a similar outcome: a higher proliferation rate in the prefrontal cortex of no-surgery pups. Moreover, synaptic density values were higher in the no-surgery pups, but there was no difference observed among pups who underwent general anesthesia, hysterotomy, and fetal surgery. Lastly, there was no difference in gliosis among the 4 groups.

CONCLUSION

In rabbits, fetal surgery through hysterotomy under maternal general anesthesia did not affect brain development, in addition to the effects of general anesthesia per se.

Fetally-injected drugs for immobilization and analgesia do not modify fetal brain development in a rabbit model

OBJECTIVE

During fetal surgery, fetuses receive medication (atropine-fentanyl-curare) to prevent fetal pain, movement and bradycardia. Although essential there has been no detailed review of potential side effects. Herein we aimed to assess the effects of this medication cocktail on fetal brain development in a rabbit model.

METHODS

Pregnant does underwent laparotomy at 28 days of gestation. Two pups of each horn were randomized to an ultrasound guided injection with medication (atropine-cisatracurium-fentanyl, as clinically used) or saline (sham). The third pup was used as control. At term, does were delivered by cesarean. Outcome measures were neonatal biometry, neuromotoric functioning and neuro-histology (neuron density, synaptic density and proliferation).

RESULTS

Maternal vital parameters remained stable during surgery. Fetal heart rates did not differ before and after injection, and were comparable for the three groups. At birth, neonatal body weights and brain-to-body weight ratios were also comparable. Both motor and sensory neurobehavioral scores were comparable. There were no differences in neuron density or proliferation. Sham pups, had a lower synaptic density in the hippocampus as compared to the medication group, however there was no difference in the other brain areas.

CONCLUSION

In the rabbit model, fetal medication does not appear to lead to short-term neurocognitive effects.

Clashes of consensus: on the problem of both justifying abortion of fetuses with Down syndrome and rejecting infanticide

Although the abortion of fetuses with Down syndrome has become commonplace, infanticide is still widely rejected. Generally, there are three ways of justifying the differentiation between abortion and infanticide: by referring to the differences between the moral status of the fetus versus the infant, by referring to the differences of the moral status of the act of abortion versus the act of infanticide, or by separating the way the permissibility of abortion is justified from the way the impermissibility of infanticide is justified. My argument is that none of these ways justifies the abortion of fetuses diagnosed with Down syndrome while simultaneously rejecting infanticide. Either the justification for abortion is consistent with infanticide, or it is implausible to justify abortion while rejecting infanticide. I conclude the article by making some preliminary remarks about how one might manage the situation posed by my argument.

Current status of fetal neurodevelopmental assessment: Four-dimensional ultrasound study

With the latest advent of four-dimensional (4-D) ultrasound, fetal neurobehavioral or neurodevelopmental assessment can be easily and readily performed. Using this technique, typical fetal movements and behavioral patterns have become apparent in all three trimesters of pregnancy. In twin pregnancy, 4-D ultrasound facilitates the precise evaluation of inter-twin contact and intra-pair stimulation. New fetal neurobehavioral assessment tests, such as Kurjak's Antenatal Neurodevelopmental Test and the Fetal Observable Movement System, may reflect the normal and abnormal neurological development of the fetus, and will facilitate more precise assessments of fetal neurobehavior or neurodevelopment, and fetal brain and central nervous system functions. In this review article, I also discuss interesting topics regarding maternal and fetal stress, fetal pain, and fetal consciousness. Four-dimensional ultrasound has opened the door to new scientific fields, such as 'fetal neurology' and 'fetal psychology,' and fetal neurobehavioral science is at the dawn of a new era. Knowledge on fetal neurobehavior and neurodevelopment will be advanced through fetal behavioral research using this technique.

Neonatal pain and developmental outcomes in children born preterm: a systematic review

BACKGROUND

Neonates cared for in neonatal intensive care units are exposed to many painful and stressful procedures that, cumulatively, could impact later neurodevelopmental outcomes. However, a systematic analysis of these effects is yet to be reported.

OBJECTIVES

The aim of this research was to review empirical studies examining the association between early neonatal pain experiences of preterm infants and the subsequent developmental outcomes of these children across different ages.

METHODS

The literature search was performed using the PubMed, PsycINFO, Lilacs, and SciELO databases and included the following key words: "pain," "preterm," and "development." In addition, a complementary search was performed in online journals that published pain and developmental studies to ensure all of the target studies had been found. The data were extracted according to predefined inclusion and exclusion criteria.

RESULTS

Thirteen studies were analyzed. In infants born extremely preterm (gestational age ≤29 wk) greater numbers of painful procedures were associated with delayed postnatal growth, with poor early neurodevelopment, high cortical activation, and with altered brain development. In toddlers born very preterm (gestational age ≤32 wk) biobehavioral pain reactivity-recovery scores were associated with negative affectivity temperament. Furthermore, greater numbers of neonatal painful experiences were associated with a poor quality of cognitive and motor development at 1 year of age and changes in cortical rhythmicity and cortical thickness in children at 7 years of age.

CONCLUSIONS

For infants born preterm, neonatal pain-related stress was associated with alterations in both early and in later developmental outcomes. Few longitudinal studies examined the impact of neonatal pain in the long-term development of children born preterm.

Fetal Consciousness: Four-dimensional Ultrasound Study

How to cite this article

Hata T, Kanenishi K, AboEllail MAM, Marumo G, Kurjak A. Fetal Consciousness: Four-dimensional Ultrasound Study. Donald School J Ultrasound Obstet Gynecol 2015;9(4):471-474.

HDlive and 4D Ultrasound in the Assessment of Fetal Facial Expressions

Four-dimensional (4D) sonographic assessment of fetal facial expressions is considered to reflect normal and abnormal fetal neurological developments, and may be an important clue to predict the fetal brain function and well-being before and after birth. HDlive is a new surface-rendering mode, which uses an adjustable light source that facilitates the ability to create lighting and shadowing effects, thereby increasing depth perception. This technique facilitates extraordinarily realistic imaging of the fetal face, making it almost impossible to differentiate between actual photographs and HDlive images. In this article, we discuss recent topics regarding fetal facial expressions assessed by 4D ultrasound and HDlive, focusing on mouthing, sucking, yawning, blinking, tongue expulsion, scowling (pain/distress), and smiling. Moreover, we consider possibility of the existence of fetal emotion or awareness.

How to cite this article

Hata T, Kanenishi K, Hanaoka U, Marumo G. HDlive and 4D Ultrasound in the Assessment of Fetal Facial Expressions. Donald School J Ultrasound Obstet Gynecol 2015;9(1):44-50.

4D ultrasound study of fetal facial expressions at 20-24 weeks of gestation

OBJECTIVE

To assess the frequency of fetal facial expressions at 20-24 weeks of gestation using four-dimensional (4D) ultrasonography and to determine whether there was any correlation between facial expression and gestational age (20-34 weeks).

METHODS

The facial expressions of 23 healthy fetuses were examined using 4D ultrasound at 20-24 weeks. Each fetus was recorded continuously for 15 minutes. The frequencies of mouthing, yawning, smiling, tongue expulsion, scowling, sucking, and blinking were assessed and the data combined with those expressions observed at 25-34 weeks of gestation in two previous studies (n = 34) to determine the correlation between gestational age and each of the facial expressions.

RESULTS

Mouthing was significantly more frequent than the other six facial expressions at 20-24 weeks (P < 0.05). Yawning was significantly more frequent than smiling, scowling, and blinking (P < 0.05), and sucking was significantly more frequent than smiling, scowling, and blinking (P < 0.05). The frequency of yawning, smiling, tongue expulsion, scowling, and blinking increased with gestational age (P < 0.05). Mouthing movement and sucking frequencies remained constant between 20 and 34 weeks.

CONCLUSION

Frequencies of complicated facial expressions such as smiling and scowling may increase with advancing gestation owing to the development of the fetal brain and central nervous system.

Effects of white noise and holding on pain perception in newborns

This experimental study on newborns was conducted to compare the effects of various atraumatic care procedures during an infant's crying response to pain. Included in this study were 120 newborns chosen from among healthy infants admitted to the Obstetrics Department of Çanakkale State Hospital between April 2010 and June 2010. The patients were divided into three physically homogeneous groups. Infants in group 1 were held on the mothers' laps, infants in group 2 were held on the mother's laps and listened to white noise, and infants in group 3 lay in their cribs and listened to white noise while undergoing a painful procedure. Data collection included the Neonatal Infant Pain Scale, which was used to evaluate the behavioral responses to pain during a heel prick blood draw and a newborn information sheet developed by the researcher. Changes in cardiac and respiratory rates recorded during the invasive procedure were statistically significant among the three groups (p < .05). The shortest crying period and the lowest behavioral reactions were among those infants lying in their cribs and listening to white noise. This group was then followed by the infants who listened to white noise while being held by their mothers. The highest behavioral reaction was reported by those infants who were held by their mothers but did not listen to white noise. According to the results, white noise is an effective nonpharmacologic method to control pain, reduce crying time, and positively effect vital signs. Therefore, it is recommended that the use of white noise be practiced on newborns when they undergo painful procedures.

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.

Is fetal pain a real evidence?

Due to the progress in fetal surgery, it is important to acquire data about fetal pain.

MATERIAL AND METHODS

We performed a Medline research from 1995, matching the following key words: "pain" and "fetus", with the following: "subplate", "thalamocortical", "myelination", "analgesia", "anesthesia", "brain", "behavioral states", "substance p". We focused on: (a) fetal development of nociceptive pathways; (b) fetal electrophysiological, endocrinological and behavioral reactions to stimuli and pain.

RESULTS

We retrieved 217 papers of which 157 were highly informative; some reported similar data or were only case-reports, and were not quoted. Most endocrinological, behavioral and electrophysiological studies of fetal pain are performed in the third trimester, and they seem to agree that the fetus in the 3rd trimester can experience pain. But the presence of fetal pain in the 2nd trimester is less evident. In favor of a 2nd trimester perception of pain is the early development of spino-thalamic pathways (approximately from the 20th week), and the connections of the thalamus with the subplate (approximately from the 23rd week). Against this possibility, some authors report the immaturity of the cortex with the consequent lack of awareness, and the almost continuous state of sleep of the fetus.

CONCLUSIONS

Most studies disclose the possibility of fetal pain in the third trimester of gestation. This evidence becomes weaker before this date, though we cannot exclude its increasing presence since the beginning of the second half of the gestation.

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.

Quantification of serum fentanyl concentrations from umbilical cord blood during ex utero intrapartum therapy

Fetal IM injection of fentanyl is frequently performed during ex utero intrapartum therapy (EXIT procedure). We quantified the concentration of fentanyl in umbilical vein blood. Thirteen samples from 13 subjects were analyzed. Medians and ranges are reported as follows. Weight of the newborn at delivery was 3000 g (2020-3715 g). The dose of fentanyl was 60 μg (45-65 μg). The time between IM administration of fentanyl and collection of the sample was 37 minutes (5-86 minutes). Fentanyl was detected in all of the samples, with a median serum concentration of 14.0 ng/mL (4.3-64.0 ng/mL).

Fetal medicine and treatment

Fetal medicine covers a broad spectrum of conditions that can be diagnosed before birth. Different disorders will require different treatment strategies and there is often an important ontogenetic aspect on how and when treatment can be implemented. Due to the limited availability there is a general lack of knowledge on how pharmacotherapy can be provided in the most efficient way. Until recently most knowledge about how different drugs are transferred and metabolized in the human fetus is based on very limited observational studies on concentrations of drugs in fetal blood and other fetal compartments. It might be that the rapid development of other non-invasive methods for fetal diagnostics such as isolation of fetal DNA and RNA in maternal serum, NMR imaging and other techniques could in the future be explored in fetal pharmacotherapy. Introduction of new treatment strategies are often based on extrapolation from experience in neonates and adults. However some fetal conditions are very specific for this time period in life. This especially entails disturbances in development as malformations, early growth restriction and several congenital disorders. Here it might be required to introduce new treatment strategies without any previous experience in humans. Example of this ethical dilemma is gene therapy for lung growth in severe cases of diaphragmatic hernia and early growth restriction. The risk-benefit issues need to be discussed in all these alternatives. However, it is likely that the concept of the human fetus as a potential patient is still in its infancy and with an improved understanding about fetal patho-physiology there will be a continued need for better knowledge of pharmacotherapy during this crucial time period in life.

Fetal surgery is a clinical reality

An increasing number of fetal anomalies are being diagnosed prior to birth, some of them amenable to fetal surgical intervention. We discuss the current clinical status and recent advances in endoscopic and open surgical interventions. In Europe, fetoscopic interventions are widely embraced, whereas the uptake of open fetal surgery is much less. The indications for each access modality are different, hence they cannot substitute each other. Although the stage of technical experimentation is over, most interventions remain investigational. Today there is level I evidence that fetoscopic laser surgery for twin-to-twin transfusion syndrome is the preferred therapy, but this operation actually takes place on the placenta. In terms of surgery on the fetus, an increasingly frequent indication is severe congenital diaphragmatic hernia as well as myelomeningocele. Overall maternal safety is high, but rupture of the membranes and preterm delivery remain a problem. The increasing application of fetal surgery and its mediagenicity has triggered the interest to embark on fetal surgical therapy, although the complexity as well as the overall rare indications are a limitation to sufficient experience on an individual basis. We plead for increased exchange between high volume units and collaborative studies; there may also be a case for self-regulation. Inclusion of patients into trials whenever possible should be encouraged rather than building up casuistic experience.

Evidências científicas no controle da dor no período neonatal

Objetivo: Identificar as revisões sistemáticas referentes ao controle da dor no neonato, catalogadas na Biblioteca Cochrane. Métodos: Utilizou-se os descritores pain e neonate. Resultados: Identificou-se seis publicações. Os temas abordados foram: dor resultante de procedimentos (uma revisão); métodos não-farmacológicos para o alívio da dor (duas) e métodos farmacológicos para analgesia (três). Conclusões: As revisões, de modo geral, apontam para a necessidade de condução de novos estudos clínicos, com amostras significativas e delineamentos adequados, para que mais evidências permitam instituir adequado controle da dor neonatal na prática clínica.

FETAL PAIN

The concept of fetal pain is becoming more and more relevant since the possibilities for invasive intrauterine treatment are increasing. However, there is much debate as to whether the fetus is mature enough to be able to perceive pain. But what is ‘pain’? One cannot determine whether a fetus feels pain unless one has a conception of what pain is. There is a difference in opinion about what pain really is and that is also the difficulty in studies on fetal pain: we cannot simply ask the fetus whether or not it feels pain. We can only give indirect evidence of possible harmful effects of stressful stimuli on the developing fetus. In this review we will first explore the meaning of ‘pain’. We will then discuss fetal anatomic, neurophysiologic and behavioural development and the responses which are thought to be required to experience pain. Finally, we discuss some ethical considerations and suggestions on fetal anaesthesia.

Fetoscopic surgery: encouraged by clinical experience and boosted by instrument innovation

Today, modern ultrasound equipment and the wide implementation of screening programmes allow the timely diagnosis of many congenital anomalies. For some of these, fetal surgery may be a life-saving option. In Europe, open fetal surgery became poorly accepted because of its invasiveness and the high incidence of postoperative premature labour and rupture of the fetal membranes. In the 1990s, the merger of fetoscopy and advanced video-endoscopic surgery formed the basis for endoscopic fetal surgery. We review the current applications of fetal surgery via both methods of access. The first clinical fetoscopic surgeries were interventions on the umbilical cord and the placenta, often referred to as obstetrical endoscopy. The outcome of a randomized clinical trial demonstrating that fetoscopic laser coagulation of chorionic plate vessels is the most effective treatment for twin-twin transfusion syndrome (TTTS) has revived interest in endoscopic fetal therapy. Operating on the fetus is another more challenging enterprise. Clinical fetal surgery programmes were virtually non-existent in Europe until minimally invasive fetoscopic surgery made such operations clinically possible as well as maternally acceptable. At present, most experience has been gathered with fetal tracheal occlusion as a therapy for severe congenital diaphragmatic hernia. As in other fields, minimally invasive surgery has pushed back boundaries and now allows safe operations to be performed on the fetal patient. Whereas minimal access seems to solve the problem of preterm labour, all procedures remain invasive, and carry a risk to the mother and a substantial risk of preterm prelabour rupture of the membranes (PPROM). The latter problem may prove to be a bottleneck for further developments, although treatment modalities are currently being evaluated.