The effect of diazepam administration during pregnancy or labor on the heart rate variability of the newborn infant

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Diabetes and hypertension increase the placental and transcellular permeation of the lipophilic drug diazepam in pregnant women

Background

Previous studies carried out in our laboratories have demonstrated impaired drug permeation in diabetic animals. In this study the permeation of diazepam (after a single dose of 5 mg/day, administered intramuscularly) will be investigated in diabetic and hypertensive pregnant women.

Methods

A total 75 pregnant women were divided into three groups: group 1 (healthy control, n = 31), group 2 (diabetic, n = 14) and group 3 (hypertensive, n = 30). Two sets of diazepam plasma concentrations were collected and measured (after the administration of the same dose of diazepam), before, during and after delivery. The first set of blood samples was taken from the mother (maternal venous plasma). The second set of samples was taken from the fetus (fetal umbilical venous and arterial plasma). In order to assess the effect of diabetes and hypertension on diazepam placental-permeation, the ratios of fetal to maternal blood concentrations were determined. Differences were considered statistically significant if p ≤ 0.05.

Results

The diabetes and hypertension groups have 2-fold increase in the fetal umbilical-venous concentrations, compared to the maternal venous concentrations. Feto: maternal plasma-concentrations ratios were higher in diabetes (2.01 ± 1.10) and hypertension (2.26 ± 1.23) groups compared with control (1.30 ± 0.48) while, there was no difference in ratios between the diabetes and hypertension groups. Umbilical-cord arterial: venous ratios (within each group) were similar among all groups (control: 0.97 ± 0.32; hypertension: 1.08 ± 0.60 and diabetes: 1.02 ± 0.77).

Conclusions

On line with our previous findings which demonstrate disturbed transcellular trafficking of lipophilic drugs in diabetes, this study shows significant increase in diazepam placental-permeation in diabetic and hypertensive pregnant women suggesting poor transcellular control of drug permeation and flux, and bigger exposure of the fetus to drug-placental transport.

Developments in CTG analysis

FHR monitoring has been the subject of many debates. The technique, in itself, can be considered to be accurate and reliable both in the antenatal period, when using the Doppler signal in combination with autocorrelation techniques, and during the intrapartum period, in particular when the FHR signal can be obtained from a fetal ECG electrode placed on the presenting part. The major problems with FHR monitoring relate to the reading and interpretation of the CTG tracings. Since the FHR pattern is primarily an expression of the activity of the control by the central and peripheral nervous system over cardiovascular haemodynamics, it is possibly too indirect a signal. In other specialities such as neonatology, anaesthesiology and cardiology, monitoring and graphic display of heart rate patterns have not gained wide acceptance among clinicians. Digitized archiving, numerical analysis and even more advanced techniques, as described in this chapter, have primarily found a place in obstetrics. This can be easily explained, since the obstetrician is fully dependent on indirectly collected information regarding the fetal condition, such as (a) movements experienced by the mother, observed with ultrasound or recorded with kinetocardiotocography (Schmidt, 1994), (b) perfusion of various vessels, as assessed by Doppler velocimetry, (c) the amount of amniotic fluid or (d) changes reflected in the condition of the mother, such as the development of gestation-induced hypertension and (e) the easily, continuously obtainable FHR signal. It is of particular comfort to the obstetrician that a normal FHR tracing reliably predicts the birth of the infant in a good condition, which makes cardiotocography so attractive for widespread application. However, in the intrapartum period, many traces cannot fulfil the criteria of normality, especially in the second stage. In this respect, cardiotocography remains primarily a screening and not so much a diagnostic method. As long as continuous monitoring of fetal acid-base balance has not been extensively tested in clinical practice, microblood sampling of the fetal presenting part (Saling, 1994) is a useful adjunct. The problem with non-normal tracings is that their significance is very often unclear. They may indicate serious fetal distress, finally resulting in preventable destruction of critical areas in the fetal brain and damage to various organs; or, on the contrary, they may indicate temporary changes in cardiovascular control as a reaction to the intermittent effects on fetal haemodynamics of, for example, uterine contractions, whether or not in combination with partial or complete compression of umbilical cord vessels or the vessels on the chorionic plate (van Geijn, 1994). Many factors influence the FHR and its variability, which further complicates the interpretation of FHR patterns; some have been discussed here in some detail. Undoubtedly, there is a need for quantitative and objective FHR analysis, as long as it does not lead to erroneous results. Close collaboration between engineers and clinicians is a prerequisite for further advances in this field. Decision support systems certainly have a future but only if they are able to take into account a large set of clinical data and can combine it with data obtained from FHR signals and other parameters referring to the fetal condition, such as fetal growth, Doppler velocimetry, amniotic fluid volume and biochemical and biophysical data obtained from the mother. Basic technical concepts inherent in computerized CTG analysis, such as sampling rate (Chang et al, 1995), signal loss, artefact detection (van Geijn et al, 1980), further processing of intervals, archiving in digitized format and monitor display, should receive considerable attention. There is still a long way to go until decision support systems find their way into obstetric practice. Further developments can only be achieved thanks to efforts of many basic and clinical researchers, wo

Mental development in late infancy after prenatal exposure to benzodiazepines--a prospective study

Seventeen infants born to mothers who used benzodiazepines (BZD) throughout pregnancy were followed prospectively and compared with 29 infants born to mothers who had not used psychoactive substances. On the Griffiths' Developmental Scale, the BZD-exposed infants demonstrated consistently lower mean GQs and DQs for all subscales at 5, 10 and 18 months of age. The differences in GQ reached statistical significance at 10 and 18 months. The DQs differed significantly for all subscales at 10 months and for the personal-social behaviour and hearing and speech subscales at 18 months of age. We suggest that prenatal exposure to BZD may cause a general delay in mental development up to 18 months of age.

Duration, amplitude and shape of accelerations in relation to fetal body movements in behavioral state 2F

The relationship between fetal movements and fetal heart rate accelerations was analyzed in 34 healthy near term fetuses. Periods of coincidence 2F (C2F) with a mean duration of 34 +/- 6 minutes per fetus were selected, with a total of 463 accelerations. Nineteen percent of single body movements and 71% of compilations of movements were accompanied by an acceleration. The minimal duration of single movements associated with accelerations was 4-5 seconds. Movements with associated accelerations differed significantly in duration from movements without accelerations. The duration of accelerations was strongly correlated with the duration of movements. The amplitude of accelerations was not clearly correlated with the duration of movements, but depended on the type of movement. The shape of accelerations appeared to be dependent on the timing of the various fetal movements. In 77%, the number of notches in the accelerations was equal to the number of pauses in the movement complications. A discrepancy between notches in accelerations and pauses in movements could be explained in the majority of cases when the timing of the various movements in relation to one another was considered, or by the presence of fetal mouth movements.

Teratogenic effects of benzodiazepine use during pregnancy

Eight children exposed in utero to benzodiazepines had characteristic dysmorphic features, growth aberrations, and central nervous system abnormalities from birth. Their dysmorphic characteristics resembled those of the fetal alcohol syndrome, although they had greater focal involvement of cranial nerves, with a sullen and expressionless face, and they more often had impairment of vitality at birth. One infant died and at autopsy had varying degrees of distortion of neuronal migration, with concomitant heterotopias. Five of the eight mothers had regularly consumed benzodiazepines, and the three remaining mothers had blood samples during pregnancy revealing benzodiazepine concentrations indicative of regular use. Our findings indicate that maternal consumption of benzodiazepines may be teratogenic in humans.

Effects of combined alcohol and benzodiazepine: a review

Both human and animal studies relating to the combined effects of alcohol and benzodiazepine (BZD) are reviewed. Although the combination of alcohol and BZD is sometimes associated with drug-induced deaths, drug overdoses and traffic accidents or fatalities, epidemiological information is lacking on the true extent of the combined abuse and on the patterns and prevalence of use of these two drugs. Since BZD are widely used for the short- and long-term treatment of alcoholics, these patients are deemed more at risk of developing BZD or alcohol/BZD dependence than the general population. There is a dire need for large-scale controlled studies concerning the efficacy of BZD in the long-term treatment of alcoholics. Compared to men, women are at a higher risk as far as the potential for BZD addiction is concerned, since they tend to use BZD more often. Epidemiologic studies on the patterns of use of BZD, alcohol or alcohol/BZD in pregnant women are called for. Animal models are also needed to ascertain whether prenatal exposure to both alcohol and BZD can impart long-lasting behavioral changes in the progeny. It is possible that BZD can exacerbate the damaging prenatal effects of alcohol.

The effects of chronic diazepam treatment on body weight and food intake in rats

A series of experiments are reported in all of which the effects of chronic (14-18 days) diazepam treatment on body weight were evaluated under various conditions, and one experiment in which weight gain and daily food intake were monitored simultaneously. The effect of diazepam treatment on body weight was compared to that of vehicle treatment in the following groups: (1) young adult females, (2) pregnant females, (3) shock treated young males (4) nonshocked young males. The effect of diazepam treatment on prenatally diazepam exposed and nonexposed males and females was investigated at seven months of age. Food intake was also measured during chronic diazepam and vehicle treatment. The findings show consistent and reliable differences between diazepam and vehicle treatment. Diazepam treated animals eat less in the long run and gain less weight than vehicle treated controls. Prenatal exposure to diazepam enhances the effect of diazepam treatment in adulthood.

Analysis of heart rate and beat-to-beat variability: Interval difference index

The relationshp between the RR interval length (RR) and the RR interval-to-interval differences (RR differences) was investigated. Data on heart rate were obtained from 11 newborn infants in well-defined behavioral states undergoing polygraphy. It was found that the RR differences were strongly dependent on the RR interval length in all behavioral states. The relationship between the RR differences (y) and the interval length (RR) could be described by the equation y = alpha (RR-320)1.5 for the interval length in the investigated range from 375 to 605 msec. On the basis of this relationship the interval difference index (ID index) was constructed for the quantification of beat-to-beat heart rate variability. The ID index showed good independence from the long-term irregularity index (LTI index). Other statistical parameters proposed for the quantification of beat-to-beat heart rate variability are discussed and compared with the ID index.