Fetal exposure to narcotics: neonatal sleep as a measure of nervous system disturbance

An Amplitude-Integrated EEG Evaluation of Neonatal Opioid Withdrawal Syndrome

OBJECTIVE

 Infants with neonatal opioid withdrawal syndrome (NOWS) have disrupted neurobehavior that requires hospitalization and treatment. This article aimed to evaluate electroencephalography (EEG) abnormalities using amplitude-integrated EEG (aEEG) in NOWS.

STUDY DESIGN

 Eighteen term born infants with NOWS were recruited prospectively for an observational pilot study. aEEG monitoring was started within 24 hours of recruitment and twice weekly through discharge. aEEG data were analyzed for background and seizures. Severity of withdrawal was monitored using the modified Finnegan scoring (MFS) system.

RESULTS

 Fifteen neonates had complete datasets. Thirteen (87%) had continuous aEEG background in all recordings. None had sleep-wake cyclicity (SWC) at initial recording. Brief seizures were noted in 9 of 15 (60%) infants. Lack of SWC was associated with higher MFS scores. At discharge, 8 of 15 (53%) had absent or emerging SWC.

CONCLUSION

 aEEG abnormalities (absent SWC) are frequent and persist despite treatment at the time of discharge in the majority of patients with NOWS. Brief electrographic seizures are common. Neonates with persistent aEEG abnormalities at discharge warrant close follow-up.

KEY POINTS

· EEG abnormalities are common and persist after clinical signs resolve in patients with NOWS.. · Short subclinical seizures may be seen.. · aEEG may identify neonates who need follow-up..

Reconceptualizing non-pharmacologic approaches to Neonatal Abstinence Syndrome (NAS) and Neonatal Opioid Withdrawal Syndrome (NOWS): A theoretical and evidence-based approach. Part II: The clinical application of nonpharmacologic care for NAS/NOWS

There has been increasing emphasis on the importance of the development of self-regulatory capacities of the individual as the cornerstone of development. The caregivers' abilities to manage their own attention, emotions, physiology and behaviors influence the development of the child's self-regulatory and interactive capacities, and thereby their overall development. Newborns prenatally exposed to psychoactive substances and/or to other prenatal stressors such as maternal poor nutrition, increased maternal stress, trauma, difficult and/or impoverished environments, in tandem with genetic predispositions, can result in alterations to their neurodevelopment that predispose them to self-regulatory problems that can be expressed at any stage of life. The care of infants with Neonatal Abstinence Syndrome (NAS)/Neonatal Opioid Withdrawal Syndrome (NOWS) and their mother/caregiver is a window of opportunity to assess the regulatory and co-regulatory capacities of both, and to provide holistic interventions with the goal of empowering the mother/caregiver in their own self-knowledge/self-regulation capacities and their crucial role in promoting the healthy development of their children. Non-pharmacologic care for the infant with NAS/NOWS is the first line of treatment and of paramount importance. Yet, current approaches are based on a limited scope of infant functioning, and the scoring systems in current use do not result in individualized and specific non-pharmacologic care of the infant, which can result in excessive or insufficient medication and a lack of caregiver appreciation for the infant's strengths, difficulties and early development. The interventions described here are based on the infant's signs of dysregulation in four neurobehavioral subsystems that can be dysregulated by NAS/NOWS, the infant's adaptive or maladaptive responses to return to a regulated functioning, and the co-regulatory behaviors of the infant and the mother/caregiver. In Part I of this two-part series on re-conceptualizing non-pharmacologic care for NAS/NOWS we laid the foundation for a new treatment approach, one grounded in developmental theory and evidence-based observations of infant and interpersonal neurobiology. Here, in Part II, we outline actionable, individually tailored evaluations and approaches to non-pharmacologic NAS/NOWS treatment based on strategies to support the regulatory capacities and development of 4 key domains: 1) autonomic; 2) motor/tone; 3) sleep/awake state control; and 4) sensory modulation subsystems.

Amplitude-integrated EEG in infants with neonatal abstinence syndrome

BACKGROUND

To describe amplitude-integrated encephalogram (aEEG) characteristics of neonates with neonatal abstinence syndrome (NAS).

METHODS

This is a prospective observational study. Newborns exposed to prenatal opioids and their gestational matched controls were included. A single-channel aEEG was obtained using Olympic 6000 CFM monitor. The background activity (continuous/discontinuous), the amplitudes (μV) and the presence of sleep-wake cycle (SWC) were documented.

RESULTS

A total of 59 infants, 23 with NAS and 36 controls were enrolled. All aEEG were completed within 48 hours of life prior to initiation of treatment. Birth weight and gestational age were similar in both groups. An aEEG was abnormal (discontinuous pattern and/or absent SWC) in 78 % (18/23) of infants with NAS versus only 25% in control group (9/36), [OR 10.8, CI (2.7-46.5) P < 0.001]. 61% of infants with NAS had discontinuous pattern [OR 7.8, CI (2-32) P = 0.001] and 39% had absence of sleep-wake cycle [OR 7.1, CI (1.4-39.4) P = 0.007].

CONCLUSIONS

A majority of infants with NAS have abnormal aEEG activity.

Neonatal abstinence syndrome

Neonates exposed prenatally to opioids will often develop a collection of withdrawal signs known as neonatal abstinence syndrome (NAS). The incidence of NAS has substantially increased in recent years placing an increasing burden on the healthcare system. Traditional approaches to assessment and management have relied on symptom-based scoring tools and utilization of slowly decreasing doses of medication, though newer models of care focused on non-pharmacologic interventions and rooming-in have demonstrated promise in reducing length of hospital stay and medication usage. Data on long-term outcomes for both traditional and newer approaches to care of infants with NAS is limited and an important area of future research. This review will examine the history, incidence and pathophysiology of NAS. We will also review diagnostic screening approaches, scoring tools, differing management approaches and conclude with recommendations for continued work to improve the care of infants with NAS.

After NAS

Mothers have used opioids for thousands of years but neonatal abstinence syndrome (NAS) or rather, survivors of NAS, is a modern phenomenon. Unrecognized and/or untreated opioid withdrawal was almost always fatal but with greater awareness and standardization of treatment, NAS is now an uncommon direct cause of infant death. However, opioids are now increasingly accessible and potent and the outcomes of children after the neonatal period are of great concern, especially when coupled with multiple other social and health risks. Complex individual, environmental and genetic factors need to be considered when assessing outcomes or future research for babies with NAS. Any intervention or research efforts must address these multifactorial complexities. This review will discuss pertinent post neonatal outcomes, including mortality, physical and mental health and social functioning of children with a history of NAS.

Beyond the Finnegan scoring system: Novel assessment and diagnostic techniques for the opioid-exposed infant

Infants with in-utero opioid exposure are most commonly assessed using the Finnegan Neonatal Abstinence Scoring System (FNASS) or a modified version of that tool. Traditionally, the purpose of these tools has been to characterize the extent of withdrawal signs to guide the pharmacologic treatment for infants with neonatal opioid withdrawal syndrome (NOWS). In the past decade however, in response to some of the limitations of the FNASS tool, there has been an increasing emphasis on developing novel assessment tools not based on the FNASS in addition to the promotion of non-pharmacologic treatment options as the first line treatment for infants with opioid exposure. Additionally, several prediction tools that may be useful in determining which patients are at high or low risk for receiving pharmacologic therapy have been developed. In this review, we will evaluate the clinical utility of these novel tools and will consider new avenues for future research.

EEG Findings in Infants With Neonatal Abstinence Syndrome Presenting With Clinical Seizures

Neonatal abstinence syndrome (NAS) refers to a constellation of signs occurring in newborn infants who were exposed to opioids or opiates in utero. These manifestations include poor feeding, gastrointestinal disorders, abnormal sleep patterns, and neurological signs such as jitteriness, tremors, and seizures (1, 2). Myoclonus, jitteriness, and tremors often may be interpreted as seizures and therefore treated as epileptic seizures. Objective: To determine whether seizure like activity observed in infants with NAS correlate with electroencephalogram (EEG) findings. Design/ Method: We reviewed the standard EEG or video electroencephalogram (VEEG) of infants with NAS who were admitted because of seizure-like clinical activity. The exclusion criteria were major neurological anomalies, hypoxic ischemic encephalopathy, metabolic disorders, or with clinical diagnosis other than NAS. Results: Forty neonates met study criteria; 28 had standard EEG recordings and 18 had VEEG. Mean gestational age was 38.5 weeks. The onset of seizure-like clinical activity was as early as day 1 and as late as day 16 of life. The clinical seizure-like activity described at the referring hospital were jerking, rhythmic movement of the extremities, or tremors. Only three (7.5%) neonates had epileptic seizures. There were increased sharp transients in frontal, central, temporal, and or occipital regions. VEEG showed disturbed non-rapid eye movement (REM) sleep with frequent arousal, jittery movements, or sleep myoclonus. Conclusion: Clinical seizure-like activity correlates poorly with epileptic seizures in infants with NAS. In neonates with NAS, a VEEG would be useful to determine if the clinical seizure-like activity is of epileptic origin or not, prior to initiation of anti-seizure medications.

Sleep Disturbances in Newborns

The purpose of this review is to serve as an introduction to understanding sleep in the fetus, the preterm neonate and the term neonate. Sleep appears to have numerous important roles, particularly in the consolidation of new information. The sleep cycle changes over time, neonates spend the most time in active sleep and have a progressive shortening of active sleep and lengthening of quiet sleep. Additionally, the sleep cycle is disrupted by many things including disease state and environment, and the amplitude integrated EEG can be a useful tool in evaluating sleep, and sleep disturbances, in neonates. Finally, there are protective factors for infant sleep that are still being studied.

Research gaps on methadone harms and comparative harms: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

Methadone-associated overdose deaths have dramatically increased. In order to inform an evidence-based clinical practice guideline to improve safety of methadone prescribing, the American Pain Society commissioned a systematic review on various aspects related to methadone safety. We searched Ovid MEDLINE, Cochrane Library, and PsycINFO databases through July 2012 to identify studies that addressed 1 or more of 17 Key Questions related to methadone safety; an update search was performed in 2014 for new studies related to methadone-related overdose and risks related to cardiac arrhythmias. A total of 168 studies met inclusion criteria for the review. The purpose of this article is to highlight critical research gaps in the literature related to methadone safety. These include lack of evidence on risk factors associated with methadone-overdose deaths and adverse events, limited evidence to evaluate the comparative mortality of methadone versus other opioids, insufficient evidence to fully understand the harms associated with methadone use during pregnancy, and insufficient evidence to determine effects of risk mitigation strategies such as electrocardiogram monitoring, strategies for managing patients with prolonged QTc intervals on screening, urine drug testing, alternative dosing regimens for initiation and titration of therapy, and timing of follow-up. Therefore, most guideline recommendations are based on weak evidence. More research is needed to guide safe methadone prescribing practices and decrease the adverse events associated with methadone.

PERSPECTIVE

This article summarizes critical research gaps in the literature related to methadone safety, based on a systematic review commissioned by the American Pain Society. Critical research gaps were identified in a number of areas, highlighting the need for additional research to guide safer prescribing and risk mitigation strategies.

Somatosensory and auditory processing in opioid-exposed newborns with neonatal abstinence syndrome: a magnetoencephalographic approach

OBJECTIVE

Opioid exposure during pregnancy is a potential risk factor for the developing central nervous system of the fetus. We studied evoked responses in buprenorphine-exposed newborns who displayed neonatal abstinence syndrome (NAS) to elucidate the possible alterations in functioning of the somatosensory and auditory systems.

METHODS

We compared somatosensory (SEFs) and auditory evoked magnetic fields (AEFs), recorded with magnetoencephalography (MEG), of 11 prenatally buprenorphine-exposed newborns with those of 12 healthy newborns. Peak latencies, source strength and location of SEFs or AEFs were recorded.

RESULTS

AEFs were present in all buprenorphine-exposed newborns without significant differences from those of healthy newborns. In contrast, though no group level differences in SEFs existed, at individual level the response deviated from the typical neonatal morphology in four buprenorphine-exposed newborns.

CONCLUSIONS

Although buprenorphine exposure during pregnancy does not seem to cause constant deficiencies in somatosensory or auditory processing, in some newborns the typical development of somatosensory networks may be - at least transiently - disrupted.

Fetal assessment before and after dosing with buprenorphine or methadone

AIM

To determine pre- and post-dosing effects of prenatal methadone compared to buprenorphine on fetal wellbeing.

DESIGN

A secondary analysis of data derived from the Maternal Opioid Treatment: Human Experimental Research (MOTHER) study, a double-blind, double-dummy, randomized clinical trial.

SETTING

Six United States sites and one European site that provided comprehensive opioid-dependence treatment to pregnant women.

PARTICIPANTS

Eighty-one of the 131 opioid-dependent pregnant women completing the MOTHER clinical trial, assessed between 31 and 33 weeks of gestation.

MEASUREMENTS

Two fetal assessments were conducted, once before and once after study medication dosing. Measures included mean fetal heart rate (FHR), number of FHR accelerations, FHR reactivity in the fetal non-stress test (NST) and biophysical profile (BPP) score.

FINDINGS

Significant group differences were found for number of FHR accelerations, non-reactive NST and BPP scores (all Ps < 0.05). There were no significant group differences before time of dosing. Significant decreases (all Ps < 0.05) occurred from pre- to post-dose assessment for mean FHR, FHR accelerations, reactive NST and fetal movement. The decrease in accelerations and reactive NST were significant only for fetuses in the methadone group, and this resulted in a significantly lower likelihood of a reactive NST compared to fetuses in the buprenorphine group.

CONCLUSION

Buprenorphine compared with methadone appears to result in less suppression of mean fetal heart rate, fetal heart rate reactivity and the biophysical profile score after medication dosing and these findings provide support for the relative safety of buprenorphine when fetal indices are considered as part of the complete risk-benefit ratio.

Patterns in sleep-wakefulness in three-month old infants exposed to methadone or buprenorphine

BACKGROUND

Infants exposed to opioides in-utero frequently demonstrate withdrawal symptoms in the neonatal period and have difficulties with state regulation.

AIM

This study examines sleep-wakefulness-distress patterns as indicators of regulatory mechanisms at 3 months of age.

PARTICIPANTS

A national infant cohort (N=35) born to women in high-dose maintenance treatment during pregnancy and a comparison group (N=36) of low-risk infants born in the same period.

OUTCOME MEASURES

Distributions and frequencies of sleep, wakefulness and distress measured in hours and episodes on sleep charts recorded by the mothers in the two groups.

RESULTS

Women in maintenance treatment were monitored closely during pregnancy to avoid illicit drug use and to be prepared for motherhood. They were also offered residential treatment before pregnancy and after the child was born. There were no statistical differences between the two groups in any of the 10 measures reflecting diurnal and nocturnal rhythmicity at 3 months despite of neonatal abstinence syndrome in 47% of the exposed infants and significant differences in infant characteristics with respect to birth weight, gestational age and maternal characteristics.

CONCLUSIONS

Follow-up procedures combining drug monitoring and counseling during pregnancy and in the first months after birth enhance the development of state regulation in terms of sleep-wakefulness patterns.

Development of the fetal lung

The development of the fetal lung compared to that of other organs is unusual in the degree of its dependence on extrinsic stimuli. When the space available to the growing lung is limited by space-occupying lesions or when the diaphragm is paralysed, lung growth is markedly impaired. The relationship of lung volume to growth may depend on lung distension. Lung hypoplasia associated with experimental procedures causing inhibition or blunting of fetal breathing movements suggests that the distending forces may be generated by these movements. Maturation is less dependent on distension and more dependent on the hormonal environment. Distensibility and stability of the lung in fetal sheep develops rapidly within a few days of birth and correlates strongly with the plasma cortisol concentration. Hypophysectomy retards mutation which is restored by infusing adrenocorticotropin but not cortisol into the fetus. The hormones mainly responsible for controlling the various aspects of maturation probably include cortisol, iodothyronines and catecholamines but the interrelationships of these hormones and the extent of involvement of other hormones is uncertain.

Concentrations of methadone in breast milk and plasma in the immediate perinatal period

This study evaluates concentrations of methadone in breast milk and plasma among a sample of methadone-maintained women in the immediate perinatal period. Twelve methadone-maintained, lactating women provided blood and breast milk specimens 1, 2, 3, and 4 days after delivery. Specimens were collected at the time of trough (just before methadone dose) and peak (3 hours after dosing) maternal methadone levels. Paired specimens of foremilk (prefeed) and hindmilk (postfeed) were obtained at each sampling time. Although there was a significant increase in methadone concentration in breast milk over time for the peak postfeed sampling time, t (22)=2.40, P=.0255, methadone concentrations in breast milk were small, ranging from 21 to 314 ng/mL, and were unrelated to maternal methadone dose. Results obtained from this study contribute to the recommendation of breastfeeding for methadone-maintained women regardless of methadone dose.

Opioids, sleep architecture and sleep-disordered breathing

Opioid use whether acute or chronic, illicit or therapeutic is prevalent in Western societies. Opioid receptors are located in the same nuclei that are active in sleep regulation and opioid peptides are suggested to be involved in the induction and maintenance of the sleep state. mu-Opioids are the most commonly used opioids and are recognized respiratory depressants that cause abnormal awake ventilatory responses to hypercapnia and hypoxia. Abnormal sleep architecture has been reported during the process of opioids induction, maintenance and withdrawal. During induction and maintenance of opioid use there is reduction of rapid eye movement (REM) sleep and slow wave sleep. More recently, central sleep apnoea (CSA) has been reported with chronic opioid use and 30% of stable methadone maintenance treatment patients have CSA. Given these facts, it is sobering to note the paucity of human data available regarding the effects of short and long-term opioid use on sleep architecture and respiration during sleep. In this manuscript, we review the current knowledge regarding the effects of mu-opioids on sleep and respiration during sleep and suggest research pathways to advance our knowledge and to explore the possible responsible mechanisms related to these effects.

Buprenorphine-containing treatments: place in the management of opioid addiction

Although the synthetic opioid buprenorphine has been available clinically for almost 30 years, its use has only recently become much more widespread for the treatment of opioid addiction. The pharmacodynamic and pharmacokinetic profiles of buprenorphine make it unique in the armamentarium of drugs for the treatment of opioid addiction. Buprenorphine has partial mu-opioid receptor agonist activity and is a kappa-opioid receptor antagonist; hence, it can substitute for other micro-opioid receptor agonists, yet is less apt to produce overdose reactions or dysphoria. On the other hand, buprenorphine can block the effects of opioids such as heroin (diamorphine) and morphine, and can even precipitate withdrawal in individuals physically dependent upon these drugs. Buprenorphine has significant sublingual bioavailability and a long half-life, making administration on a less than daily basis possible. Furthermore, its discontinuation is associated with only a mild withdrawal syndrome. Clinical trials have demonstrated that sublingual buprenorphine is effective in both maintenance therapy and detoxification of individuals addicted to opioids. The introduction of a sublingual formulation combining naloxone with buprenorphine further reduces the risk of diversion to illicit intravenous use. Because of its relative safety and lower risk of illegal diversion, buprenorphine has been made available in several countries for treating opioid addiction in the private office setting, greatly enhancing treatment options for this condition.

Prenatal Cocaine Exposure and Infant Sleep at 7 Months of age: The Influence of the Caregiving Environment

The primary goal of this study was to examine sleep problems in a sample of cocaine-exposed 7-month-old infants and to determine if maternal psychopathology mediated any existing association between substance exposure and sleep behaviors. We also examined the differences in sleep behaviors of cocaine-exposed infants in parental custody and cocaine-exposed infants in nonparental custody. Participants were 65 cocaine-exposed and 53 nonexposed infants and their primary caregivers who were recruited at delivery and assessed at 7 months of infant age. As expected, women who used cocaine during pregnancy had more psychiatric symptoms than nonusers. Prenatal exposure to heavier amounts of cocaine was significantly related to more severe sleep difficulties, and maternal anxiety mediated this association. Approximately 28% of cocaine mothers lost custody of their infants by 7 months of age. Nonmaternal caregivers had significantly fewer symptoms of psychopathology than the cocaine-using women who retained custody of their children. Infants who were in nonparental care at 7 months of age also had less severe sleep problems than did infants who remained in parental care.

Differential effects of gestational buprenorphine, naloxone, and methadone on mesolimbic mu opioid and ORL1 receptor G protein coupling

In addition to its use for heroin addiction pharmacotherapy in general, buprenorphine has advantages in treating maternal heroin abuse. To examine the gestational effects of buprenorphine on opioid receptor signaling, the [(35)S]-GTP gamma S in situ binding induced by the mu agonist [D-Ala(2),MePhe(4),Gly(5)-ol] enkephalin (DAMGO) or the nociceptin/orphanin FQ (N/OFQ) agonist was measured in mesolimbic structures of pup brains from pregnant rats administered with buprenorphine +/- naloxone, naloxone, or methadone by osmotic minipump. Drug- and gender-based changes in DAMGO- and N/OFQ-induced GTP gamma S binding were discovered in mesolimbic regions of dam, P2, and P7 brains. Buprenorphine and/or methadone gestational treatment attenuated DAMGO-induced GTP gamma S binding in some dam and male P2 mesolimbic regions. Methadone diminished DAMGO-induced GTP gamma S binding in almost all monitored brain regions of the dam but had few effects on their N/OFQ-induced GTP gamma S binding. Naloxone used in combination with buprenorphine blocked the inhibition by buprenorphine alone on DAMGO-induced GTP gamma S binding. In contrast to its inhibitory effects on DAMGO-induced GTP gamma S binding, buprenorphine stimulated N/OFQ-induced GTP gamma S binding in male P2 nucleus accumbens and lateral septum. Brain region-dependent gender differences in DAMGO-induced GTP gamma S binding were seen in P2 pups, and males showed greater sensitivity to buprenorphine and methadone than females. Our findings on mu opioid receptor (MOR) GTP-binding regulatory protein (G protein) coupling and its gender dependency are consistent with our earlier studies on mu receptor binding adaptation induced by buprenorphine in dams and neonatal rats after in utero treatment regimens, and they extend the gestational effects of this opiate to mu and N/OFQ receptor functionality.

Buprenorphine: an analgesic with an expanding role in the treatment of opioid addiction

Buprenorphine, a long-acting opioid with both agonist and antagonist properties, binds to mu-opioid (OP(3)), kappa-opioid (OP(2)), delta-opioid (OP(1)), and nociceptin (ORL-1) receptors. Its actions at these receptors have not been completely characterized, although buprenorphine is generally regarded as a mu-opioid receptor partial agonist and a kappa-opioid receptor antagonist. Its pharmacology is further complicated by an active metabolite, norbuprenorphine. Although buprenorphine can be used as an analgesic agent, it is of greater importance in the treatment of opioid abuse. Because of its partial agonist activity at mu-opioid receptors and its long half-life, buprenorphine has proven to be an excellent alternative to methadone for either maintenance therapy or detoxification of the opioid addict. Although buprenorphine may ultimately prove to be superior to methadone in the maintenance of the pregnant addict, its effects on the developing fetus must be carefully evaluated.

The role of opioid receptors in morphine withdrawal in the infant rat

Exposure to opiates such as morphine can lead to psychological and physical dependence in both adult and infant humans. Infant rats experience opiate withdrawal behaviors that are qualitatively different from the withdrawal behaviors displayed by adult rats. In the adult, withdrawal is largely mediated by the mu-opioid receptor. We sought to understand more about what role each opioid receptor (mu, kappa, and delta) plays in the display of the physical withdrawal in the infant rat. Beginning on postnatal day 1, infant rats were injected with morphine sulfate twice a day for 6.5 days. On the afternoon of the seventh day the infant rats were given an i.c. injection of a vehicle, the mu-opioid receptor antagonist CTOP, the kappa-opioid receptor antagonist nor-BNI, or the delta-opioid receptor antagonist naltrindole. CTOP precipitated withdrawal behaviors in the 7-day-old rat in a dose-dependent manner. Neither nor-BNI nor naltrindole induced any significant changes in the frequency of the withdrawal behaviors. These data suggest that in the infant rat control of certain behavioral withdrawal signs is modulated primarily by the mu-opioid receptor, as is the case in the adult rat.

Effect of prenatal opioid exposure on cholinergic development

Opioid drugs such as methadone or buprenorphine are often used in the management of pregnant addicts. These drugs are generally thought of as nonteratogenic and preferable to repeated cycles of withdrawal in utero. However, evidence exists that perinatal exposure to these opioids delays and disrupts cholinergic development, particularly in the striatum. Acetylcholine (ACh) content and the expression of choline acetyltransferase protein and mRNA are reduced in the early postnatal period by prenatal opioid exposure in the rat. Although these indicators of the cholinergic phenotype return to normal levels over time, the activity of the cholinergic neurons remains disrupted, with a large increase in ACh turnover rate. The mechanism of these effects is unknown, but may involve changes in the expression of nerve growth factor, which is reduced by opioid exposure.

Intravenous fentanyl PCA during labour

PURPOSE

To evaluate the usefulness of intravenous patient-controlled analgesia (PCA) fentanyl for labour analgesia, its effectiveness for maternal pain and safety for the fetus and newborn.

METHODS

Twenty primigravidas were randomised to receive intravenous PCA fentanyl or epidural analgesia for labour pain. Maternal pain, heart rate and arterial oxyhaemoglobin saturation (SpO2) were monitored. Fetal and neonatal monitoring included cardiotocogram (CTG), APGAR, neurological scoring and static-charge-sensitive bed (SCSB) recording for 12 hr postnatally with ECG and SpO2. Fentanyl concentrations and pH of umbilical artery and vein were analysed.

RESULTS

Initially, epidural analgesia was more effective (P = 0.01), and three patients in the fentanyl group were given epidural due to unsatisfactory pain relief. Overall satisfaction for analgesia did not differ between the groups. Maternal side-effects were more frequent in the fentanyl group (dizziness and tiredness most often, P = 0.0001). Severe side-effects were not reported. In CTG there were no differences between groups. All the newborns were healthy, APGAR and pH were normal. Naloxone was not used. Neurological scoring was similar in both groups. In 12 hr monitoring heart rate, breathing frequency and movement time were similar in both groups, but SpO2 was lower in the fentanyl group (P < 0.001). Umbilical cord fentanyl concentrations were low or beyond the detection limit.

CONCLUSION

Intravenous fentanyl can be used for labour analgesia with the doses reported here as an alternative to epidural analgesia. However, the fetus and neonate must be appropriately monitored. Naloxone and oxygen should be available if neonatal distress occurs.

Maternal polydrug use including cocaine and postnatal infant sleep architecture: preliminary observations and implications for respiratory control and behavior

Twelve-hour overnight pneumocardiograms were assessed for sleep architecture and sleep efficiency in two groups of healthy term newborn infants: a group exposed prenatally to cocaine alone or in combination with other drugs and a non-exposed group. Sleep was differentiated from wakefulness by an increase in heart rate, an increase in or variation in the duration and amplitude of the respiration and increased artifacts on the heart rate channel. Quiet and active sleep were determined by the regularity or irregularity of heart rate and respiration. In a sub-set of infants, the number of arousals during active sleep was calculated. Overall significance was confirmed by ANOVA followed by paired comparisons using the Student's-test. When compared to non-exposed infants within the first week of life, infants exposed prenatally to cocaine alone or in combination with other drugs demonstrated more wakefulness and less sleep (P < 0.05), more frequent arousals during active sleep (P < 0.01), and the tendency of a higher proportion of active sleep compared to quiet sleep. These findings may have implications to both behavioral and respiratory control findings associated with prenatal cocaine exposure.

The function of fetal/neonatal rapid eye movement sleep

The hypothesis is put forward that rapid eye movement (REM) sleep in early life serves as (1) an indicator for the degree of brain maturation and (2) the promoter of further brain development. This hypothesis, although not exclusive, differs (a) from the theory of Roffwarg et al. that REM sleep substitutes for 'wakefulness' during the period (early life) in which wakefulness is limited, (b) from the theory of Crick and Mitchson, i.e., the 'unlearning' hypothesis of REM sleep, (c) from the theory of Jouvet, i.e., that REM sleep is a time for genetic read-out and (d) from the theory of Freud, i.e., that dreams fulfil our wishes (in other words, activation of neuronal systems that were disproportionally activated during wakefulness).

Vagal tone regulation during sustained attention in boys exposed to opiates in utero

Attention and learning problems among children exposed to opiates in utero have been previously reported but are difficult to interpret due to imprecise measurement and inadequate control of postnatal factors. In this study, we used a behavior-based measure of attention (continuous-performance tasks) and a physiological index of sustained attention (cardiac vagal tone) to measure more precisely the process of sustained attention. Boys, aged 7 to 12, exposed to opiates in utero, were compared to boys whose mothers began using illicit substances after the child's birth (environmental controls), and boys whose mothers were non-drug users. This three-group design was intended to isolate in utero effects from postnatal environmental influences. Vagal tone, a measure of heart-rate variability sensitive to vagal influences on the heart, was measured pre- and postbaseline and during the three tasks of the Gordon Diagnostic System (Delay, Vigilance, and Distractibility). Vagal tone has been found to be sensitive to changes in environmental demand for sustained attention in infants, school-age children, and adults. Results indicated that when distractors were added to the vigilance task (Distractibility task), opiate-exposed boys failed to suppress vagal tone compared to both control groups. However, both the opiate-exposed boys and the environmental controls made fewer correct responses than non-drug-exposed controls on this task. These results indicate that normal physiological responses to increased attentional demand may be impaired in boys exposed in utero to opiates in this age range. However, the poor Distractibility scores of both the opiate-exposed and environmental controls suggests an important role of environmental influences on attentional performance.

Symposium: Normal and abnormal REM sleep regulation: The importance of REM sleep for brain maturation

A number of studies, some done by us, are reviewed concerning the function of foetal/neonatal REM sleep. The hypothesis is put forward that REM sleep in early life serves as an indicator for: (1) the degree of brain maturation, and (2) the promotion of further brain development. This hypothesis, although not exclusive, differs from: the original theory of Roffwarg et al. (1966) that REM sleep serves as "wakefulness" during the period in which wakefulness is limited; and also from the theory of Crick and Mitchson (1983-the "unlearning" hypothesis of REM sleep). As the functions of sleep in general, and REM sleep in particular, are still unclear, we hope this review will suggest new possibilities for future research.

Behavioral development in children prenatally exposed to drugs and alcohol

Empirical research on the behavioral consequences to the offspring of use of recreational and addictive drugs and alcohol by pregnant women is reviewed. The current epidemic of cocaine use has raised the specter of a host of "cocaine babies" whose prenatally induced impairments will interfere with social and academic functioning and constitute an immense social burden. In fact, examination of effects of drug exposure on infant behavior and subsequent development suggests a much more subtle and complicated process which must take into account not only the child's prenatal exposure but the various other environmental factors which contribute to eventual outcome. These other factors include caregiving competence and social environment.

Size for gestational age and neonatal sleep variables: behavioral indices of risk in fullterm twins

Neonatal sleep behaviors and behavioral state cycling were observed for 20 pairs of same-sex, fullterm twins in which one twin of the pair was appropriate-for-gestational-age (AGA) and the other twin was small-for-gestational-age (SGA). Time-sampling recordings were made in active sleep of number and vigor of limb movements, body and head movements, and mouth movements. No group differences were observed for time spent in first active sleep, first quiet sleep, or length of first sleep cycle. Examination of specific behaviors indicated a significantly higher incidence of vigorous limb movements and right hand-to-mouth movements, with a trend for more small limb movements and left hand-to-face movements, for AGA twins when compared with SGA twins. SGA twins had significantly more spontaneous smiles and a trend for spontaneous startles than AGA twins. A stepwise discriminant analysis indicated that a composite of the variables smile, large limb movement, startle, and left hand-to-face significantly discriminated between the two groups, with 90% correct classification of the AGA twins and 75% correct classification of the SGA twins. The results demonstrated the utility of evaluating specific sleep behaviors, rather than state cycling only, to describe differences in neonatal sleep characteristics between AGA and SGA twins.

The effect of prenatal methadone exposure on development and nociception during the early postnatal period of the rat

The effects of prenatal exposure to methadone via Alzet osmotic minipump on early postnatal development and on nociceptive behavioral endpoints were assessed in Sprague-Dawley rat pups during the first three postnatal weeks. This treatment regimen appeared to produce no maternal toxicity, with dams developing and maintaining dependence upon methadone through parturition. Methadone-exposed dams exhibited a withdrawal syndrome consisting of wet-dog shakes, diarrhea, vocalizations and irritability when challenged with naloxone 24 h postpartum. Pups exhibited a similar withdrawal syndrome following naloxone challenge consisting of mouthing and licking, hyperactive response to touch and vocalizations 24 h postpartum. Although no significant difference in litter size was evident in methadone-treated litters, a 16% pup mortality rate was observed in these litters. Prenatal methadone-exposed pups exhibited a significant body weight reduction at birth that resolved by postnatal day 2 (P2) in males and P4 in females. Methadone-exposed pups exhibited significant developmental delay in the expression of the negative geotaxic response to a morphine challenge while, conversely, 21-day-old pups exhibited a significantly reduced analgesic response to this challenge. These studies indicate that this method of prenatal exposure to methadone can produce dependence in the dam and offspring without substantial mortality, induce developmental delay and alter analgesic responses to opiate challenge in exposed pups during the preweanling period.

The effect of chronic oral methadone treatment on monkey chorionic gonadotropin, estradiol, dehydroepiandrosterone sulfate, progesterone, prolactin and cortisol levels during pregnancy in the cynomolgus monkey (Macaca fascicularis)

The effect of chronic methadone treatment upon the serum levels of Estradiol (E2), Progesterone (P), Prolactin (Prl), monkey chorionic gonadotropin (mCG), dehydroepiandrosterone sulfate (DHEAS) and Cortisol (C) in pregnant Cynomolgus monkeys (Macaca fascicularis) is described in comparison with the hormone levels in a control group. Only DHEAS was significantly decreased in late pregnancy in the methadone group. From these data it can not be concluded that methadone treatment compromises (feto)placental function. The observed intra-uterine growth retardation in the methadone treated group might be a result of a direct influence of methadone upon growth.

MIF-1 can accelerate neuromotor, EEG and behavioral development in mice

Newborn mice were injected SC daily with 1 mg/kg of MIF-1 or saline during the first 19 days of life. The progress of each pup was monitored for physical (body weight, eye and ear opening), neurobehavioral (reflexes) and neurophysiological (EEG) development until the weaning stage. In early adulthood (40 days of age) mice were tested on a maze learning task. Results indicate that MIF-1 can accelerate neurologic (days 3-9), somatic (days 10-14) and electroencephalographic (days 16-19) parameters, and that the effects of treatment last into the early adult stage with increased learning abilities in an appetitive task.

The effect of chronic methadone treatment on intra-uterine growth of the cynomolgus monkey (Macaca fascicularis)

A generally accepted management of heroin addiction during pregnancy is treatment with methadone, which reduces the complications of heroin addiction considerably. Reports in the literature are still contradictory, however, about the influence of methadone upon birthweight. In pregnant Cynomolgus monkeys (Macaca fascicularis) the effect of chronic treatment with rather high dosages of methadone upon birthweight was studied under standardized conditions. Birthweights were significantly lower in the methadone-treated animals.

Precipitated opiate abstinence in utero

Following direct infusion of morphine (0.6 to 80.0 mg/hr) to the fetal lamb for 2 to 6 hours, naloxone administration precipitated a fetal abstinence syndrome consisting of desynchronization of electrocortical activity; increased total body movements, neck tone, and eye movements; continuous rapid, deep breathing movements; immediate bradycardia associated with transient increases in systolic, diastolic, and pulse pressures; and meconium staining of the amniotic fluid. This syndrome resembles that observed in the opiate-abstinent human neonate.

Neonatal preference for visual patterns: modification by prenatal anesthetic exposure?

Exposure to anesthetic drugs during gestation has been shown to cause behavioral changes in rats, and exposure during labor and delivery also affects human neonatal behavior. In this preliminary study, nine neonates who had been exposed to anesthetic agents during gestation were tested for visual-pattern preference. These nine infants looked at the stimuli for statistically significantly longer periods compared with 30 non-exposed infants, and had significantly different preferences for some pairs of patterns. The results suggest that prenatal exposure to anesthetic agents may contribute to behavioral alterations in human neonates.

Fetal drug exposure-behavioral teratogenesis

This paper reviews the neurobehavioral and developmental effects of fetal drug exposure. The drugs most commonly associated with adverse developmental outcome include alcohol, anticonvulsants (particularly phenytoin and trimethadione), narcotics, and some environmental toxins. Major limitations of studies examining the consequences of prenatal drug exposure on development include inadequate control of other confounding factors, uncertain accuracy of drug histories, and outcome criteria that provide insufficient delineation of subtle developmental delays.

Effects of narcotic drugs on fetal behavioral activity: acute methadone exposure

The effects of acute methadone exposure on fetal behavioral activity were investigated in 10 unanesthetized fetal lamb preparations. Fetal behavioral activity was interpreted indirectly from the electrocorticogram (ECoG), electromyogram, electrooculogram, blood pressure, heart rate (FHR), and breathing movements (FBMs) of the fetus. Methadone infusion to the mother (5 micrograms/kg/min) resulted in a suppression of all synchronized ECoG activity, and an increase in FBM, FHR, eye movements, nuchal tone, and body movements. Similar effects were observed when 10% of the dose was given directly to the fetus. These results demonstrate that methadone acts directly om the fetus to suppress both quiet sleep and rapid eye movement sleep and results in a "hyperactive" state that has previously been shown to be associated with a 20% increase in fetal oxygen consumption.

Cerebral blood flow and metabolism during morphine-induced stimulation of breathing movements in fetal lambs

Brain blood flow increased in the fetal lamb during morphine-induced stimulation of breathing. The increase in flow was 60% in the cerebral hemispheres and the cerebellum, and 100% in the midbrain plus rhinencephalon, pons, medulla and cervical spinal cord. Oxygen content of arterial blood decreased in all experiments and the arterial carbon dioxide tension increased in all but one of the experiments. The increase in cerebral blood flow observed is predicted by the changes in arterial oxygen content and carbon dioxide tension. Cerebral oxygen consumption and glucose utilization were not changed by morphine treatment. These results suggest that there is no direct effect of morphine upon cerebral blood flow and metabolism in the fetal lamb during morphine-stimulated breathing.

Opiates, endorphins and the developing organism: a comprehensive bibliography

A comprehensive bibliography of the literature concerned with opiates, endorphins, and the developing organism is presented. A total of 1378 clinical and laboratory references, with citations beginning in 1875, are recorded. A series of indexed accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics. The clinical section is subdivided into: age of subject examined; maternal aspects; effects on the fetus; pharmacology, physiology, and the withdrawal syndrome; and "other" effects on the offspring. The laboratory section is subdivided into: type of opiate/endorphin studied; species utilized; and major subject areas explored.