Betamethasone effects on fetal sheep cerebral blood flow are not dependent on maturation of cerebrovascular system and pituitary-adrenal axis

Perinatal management: Lessons learned from the neonatal research network

Recent contributions of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN) regarding obstetrical perinatal interventions and neonatal delivery room practices include the following: the impact of multiple antepartum factors including maternal diabetes, hypertension, obesity and mode of delivery on outcomes of extremely preterm newborns, effects of delayed delivery interval for extremely preterm multiples, effects of antenatal steroids on preterm newborn outcomes and the impact of antenatal magnesium sulfate therapy on neurodevelopmental outcomes for extremely preterm infants. NRN studies also contribute important evidence for neonatal delivery room resuscitation guidelines including umbilical cord management and maintenance of euthermia immediately after birth. The updated NRN outcome calculator helps better counsel families regarding possible outcomes for the most immature newborns if resuscitation is attempted at birth. Thus, the NRN provides substantial information regarding effects of perinatal management on newborn infants.

Evaluation of Long-term Outcomes Associated With Preterm Exposure to Antenatal Corticosteroids: A Systematic Review and Meta-analysis

IMPORTANCE

Animal studies have found that antenatal corticosteroids affect many organs across multiple stages of life. However, the long-term outcomes in human children are not well understood.

OBJECTIVE

To conduct a systematic review and meta-analysis of long-term outcomes associated with preterm exposure to antenatal corticosteroids compared with no exposure in all children as well as children with preterm and full-term birth.

DATA SOURCES

Academic databases were searched for articles published from January 1, 2000, to October 29, 2021, including Ovid MEDLINE, Ovid Embase, PsycInfo, CINAHL (Cumulative Index of Nursing and Allied Health Literature), Web of Science, ClinicalTrials.gov, and Google Scholar. References of articles were also searched for relevant studies.

STUDY SELECTION

Randomized clinical trials (RCTs), quasi-RCTs, and cohort studies that assessed long-term neurodevelopmental, psychological, or other outcomes at 1 year or older in those who had preterm exposure to antenatal corticosteroids were included. No language restrictions were set.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data using a piloted data extraction form. Data on study population, pregnancy characteristics, exposure to antenatal corticosteroids, and outcomes were collected. Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guidelines were followed, and random-effects models were used for the meta-analysis.

MAIN OUTCOMES AND MEASURES

The primary outcome was an author-defined composite of any adverse neurodevelopmental and/or psychological disorder. The secondary outcomes included specific measures of psychological disorders; neurodevelopmental delay; and anthropometric, metabolic, and cardiorespiratory outcomes.

RESULTS

A total of 30 studies met the inclusion criteria, and involved more than 1.25 million children who were at least 1 year of age when the outcomes were assessed. Exposure to a single course of antenatal corticosteroids for children with extremely preterm birth was associated with a significant reduction in risk of neurodevelopmental impairment (adjusted odds ratio, 0.69 [95% CI, 0.57-0.84]; I2 = 0%; low certainty). For children with late-preterm birth, exposure to antenatal corticosteroids was associated with a higher risk of investigation for neurocognitive disorders (n = 25 668 children; adjusted hazard ratio [aHR], 1.12 [95% CI, 1.05-1.20]; low certainty). For children with full-term birth, exposure to antenatal corticosteroids was associated with a higher risk of mental or behavioral disorders (n = 641 487 children; aHR, 1.47 [95% CI, 1.36-1.60]; low certainty) as well as proven or suspected neurocognitive disorders (n = 529 205 children; aHR, 1.16 [95% CI, 1.10-1.21]; low certainty).

CONCLUSIONS AND RELEVANCE

Results of this study showed that exposure to a single course of antenatal corticosteroids was associated with a significantly lower risk of neurodevelopmental impairment in children with extremely preterm birth but a significantly higher risk of adverse neurocognitive and/or psychological outcomes in children with late-preterm and full-term birth, who made up approximately half of those with exposure to antenatal corticosteroids. The findings suggest a need for caution in administering antenatal corticosteroids.

Antenatal betamethasone redistributes central blood flows and preferentially augments right ventricular output and pump function in preterm fetal lambs

The glucocorticosteroid betamethasone, which is routinely administered prior to anticipated preterm birth to enhance maturation of the lungs and the cardiovascular system, has diverse fetal regional blood flow effects ranging from increased pulmonary flow to decreased cerebral flow. The aim of this study was to test the hypothesis that these diverse effects reflect alterations in major central flow patterns that are associated with complementary shifts in left ventricular (LV) and right ventricular (RV) pumping performance. Studies were performed in anesthetized preterm fetal lambs (gestation = 127 ± 1 days, term = 147 days) with (n = 14) or without (n = 12) preceding betamethasone treatment via maternal intramuscular injection. High-fidelity central arterial blood pressure and flow signals were obtained to calculate LV and RV outputs and total hydraulic power. Betamethasone therapy was accompanied by 1) increased RV, but not LV, output; 2) a greater RV than LV increase in total power; 3) a redistribution of LV output away from the fetal upper body region and toward the lower body and placenta; 4) a greater proportion of RV output passing to the lungs, and a lesser proportion to the lower body and placenta; and 5) a change in the relative contribution of venous streams to ventricular filling, with the LV having increased pulmonary venous and decreased foramen ovale components, and the RV having lesser superior vena caval and greater inferior vena caval portions. Taken together, these findings suggest that antenatal betamethasone produces a widespread redistribution of central arterial and venous flows in the fetus, accompanied by a preferential rise in RV pumping performance.

Cardiovascular effects of prenatal stress-Are there implications for cerebrovascular, cognitive and mental health outcome?

Prenatal stress programs offspring cognitive and mental health outcome. We reviewed whether prenatal stress also programs cardiovascular dysfunction which potentially modulates cerebrovascular, cognitive and mental health disorders. We focused on maternal stress and prenatal glucocorticoid (GC) exposure which have different programming effects. While maternal stress induced cortisol is mostly inactivated by the placenta, synthetic GCs freely cross the placenta and have different receptor-binding characteristics. Maternal stress, particularly anxiety, but not GC exposure, has adverse effects on maternal-fetal circulation throughout pregnancy, probably by co-activation of the maternal sympathetic nervous system, and by raising fetal catecholamines. Both effects may impair neurodevelopment. Experimental data also suggest that severe maternal stress and GC exposure during early and mid-gestation may increase the risk for cardiovascular disorders. Human data are scarce and especially lacking for older age. Programming mechanisms include aberrations in cardiac and kidney development, and functional changes in the renin-angiotensin-aldosterone-system, stress axis and peripheral and coronary vasculature. Adequate experimental or human studies examining the consequences for cerebrovascular, cognitive and mental disorders are unavailable.

Short- and long-term neonatal outcomes according to differential exposure to antenatal corticosteroid therapy in preterm births prior to 24 weeks of gestation

AIM

To assess the effects of differential exposure to antenatal corticosteroid (ACS) on short- and long-term outcomes of infants born before 24 weeks of gestation.

METHODS

This is a retrospective cohort study of 147 infants delivered by 116 women at 21-23 weeks of gestation between January 2001 and December 2016 at a tertiary referral hospital in Seoul, Korea. Eligible subjects were categorized into the following three groups according to ACS exposure: non-user (n = 53), partial-course (n = 44), and complete-course (n = 50). Univariable and multivariable analyses were used to compare neonatal mortality, neonatal morbidities including intraventricular hemorrhage (IVH), and neurodevelopmental impairment including cerebral palsy among the three groups.

RESULTS

Neonatal mortality rate was significantly lower in the ACS-user groups (non-user, 52.8%; partial-course, 27.3%; complete-course, 28.0%; P = 0.01), but complete-course of ACS therapy had no advantages over partial-course. A lower incidence of IVH was observed in the complete-course group (non-users, 54.8%; partial-course, 48.6%; complete-course, 20.5%; P = 0.003). Multiple logistic regression analysis showed that ACS therapy, either partial- or complete-course, was associated with a lower rate of neonatal mortality (adjusted odds ratio (aOR) 0.375; 95% confidence interval (CI) 0.141-0.996 in partial-course; aOR 0.173; 95% CI 0.052-0.574) in complete-course). IVH (aOR 0.191; 95% CI 0.071-0.516) was less likely to occur in the complete-course group than in the non-user group. Neurodevelopmental impairment of survivors at 18-22 month after birth was not significantly different among the three groups.

CONCLUSION

ACS therapy in preterm births at 21-23 weeks of gestation was associated with significantly reduced rates of neonatal mortality and IVH, especially with complete administration.

Association of Neurodevelopmental Outcomes and Neonatal Morbidities of Extremely Premature Infants With Differential Exposure to Antenatal Steroids

IMPORTANCE

Many premature infants are born without exposure to antenatal steroids (ANS) or with incomplete courses. This study evaluates the dose-dependent effect of ANS on rates of neonatal morbidities and early childhood neurodevelopmental outcomes of extremely premature infants.

OBJECTIVE

To compare rates of neonatal morbidities and 18- to 22-month neurodevelopmental outcomes of extremely premature infants exposed to no ANS or partial or complete courses of ANS.

DESIGN, SETTING, AND PARTICIPANTS

In this observational cohort study, participants were extremely premature infants (birth weight range, 401-1000 g; gestational age, 22-27 weeks) who were born at participating centers of the National Institute of Child Health and Human Development Neonatal Research Network between January 2006 and December 2011. Data were analyzed between October 2013 and May 2016.

MAIN OUTCOMES AND MEASURES

Rates of death or neurodevelopmental impairment at 18 to 22 months' corrected age. Neurodevelopmental impairment was defined as the presence of any of the following: moderate to severe cerebral palsy, a cognitive score less than 85 on the Bayley Scales of Infant and Toddler Development III, blindness, or deafness.

RESULTS

There were 848 infants in the no ANS group, 1581 in the partial ANS group, and 3692 in the complete ANS group; the mean (SD) birth weights were 725 (169), 760 (173), and 753 (170) g, respectively, and the mean (SD) gestational ages were 24.5 (1.4), 24.9 (2), and 25.1 (1.1) weeks. Of 6121 eligible infants, 4284 (70.0%) survived to 18- to 22-month follow-up, and data were available for 3892 of 4284 infants (90.8%). Among the no, partial, and complete ANS groups, there were significant differences in the rates of mortality (43.1%, 29.6%, and 25.2%, respectively), severe intracranial hemorrhage among survivors (23.3%, 19.1%, and 11.7%), death or necrotizing enterocolitis (48.1%, 37.1%, and 32.5%), and death or bronchopulmonary dysplasia (74.9%, 68.9%, and 65.5%). Additionally, death or neurodevelopmental impairment occurred in 68.1%, 54.4%, and 48.1% of patients in the no, partial, and complete ANS groups, respectively. Logistic regression analysis revealed that complete (odds ratio, 0.63; 95% CI, 0.53-0.76) and partial (odds ratio, 0.77; 95% CI, 0.63-0.95) ANS courses were associated with lower rates of death or neurodevelopmental impairment compared with the no ANS group. The reduction in the rate of death or neurodevelopmental impairment associated with exposure to a complete ANS course may be mediated through a reduction in rates of severe intracranial hemorrhage and/or cystic periventricular leukomalacia in the neonatal period.

CONCLUSIONS AND RELEVANCE

Antenatal steroid exposure was associated with a dose-dependent protective effect against death or neurodevelopmental impairment in extremely preterm infants. The effect was partly mediated by ANS-associated reductions in rates of severe intracranial hemorrhage and/or cystic periventricular leukomalacia. These results support prompt administration of ANS, with the goal of a complete course prior to delivery.

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as endotoxins, bacteria, umbilical cord occlusions, hypoxia and various pharmacological treatments. The life-saving clinical practices of glucocorticoid treatment in fetuses at risk of premature birth and the therapeutic hypothermia have been developed in this model. This is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation and in vivo organ imaging. Here we describe the surgical instrumentation procedure required to achieve a stable chronically instrumented non-anesthetized fetal sheep model including characterization of the post-operative recovery from blood gas, metabolic and inflammation standpoints.

Pathogenesis and prevention of intraventricular hemorrhage

Intraventricular hemorrhage (IVH) is a major neurologic complication of prematurity. Pathogenesis of IVH is attributed to intrinsic fragility of germinal matrix vasculature and to the fluctuation in the cerebral blood flow. Germinal matrix exhibits rapid angiogenesis orchestrating formation of immature vessels. Prenatal glucocorticoid exposure remains the most effective means of preventing IVH. Therapies targeted to enhance the stability of the germinal matrix vasculature and minimize fluctuation in the cerebral blood flow might lead to more effective strategies in preventing IVH.

Statins prevent adverse effects of postnatal glucocorticoid therapy on the developing brain in rats

BACKGROUND

Postnatal glucocorticoid therapy in the treatment of chronic lung disease benefits lung function, however it adversely affects brain development. We hypothesized that combined postnatal glucocorticoid and statin therapy diminishes adverse effects of glucocorticoids on the developing brain.

METHODS

On postnatal days (P) 1-3, one male pup per litter received i.p. injections of saline control (C), n = 13) or dexamethasone (0.5, 0.3, 0.1 µg/g; D, n = 13), ± pravastatin (10 mg/kg i.p.; CP, n = 12; DP, n = 15). Statins or saline continued from P4-6. At P21, brains were perfusion fixed for histological and stereological analyses.

RESULTS

Relative to controls, dexamethasone reduced total (837 ± 23 vs. 723 ± 37), cortical (378 ± 12 vs. 329 ± 15), and deep gray matter (329 ± 12 vs. 284 ± 15) volume (mm(3)), cortical neuronal number (23 ± 1 vs. 19 ± 1 × 10(6)), and hippocampal neuronal soma volume (CA1: 1,206 ± 32 vs. 999 ± 32; dentate gyrus: 679 ± 28 vs. 542 ± 24 µm(3); all P < 0.05). Dexamethasone increased the glial fibrillary acidic protein-positive astrocyte density in the white matter (96 ± 2 vs. 110 ± 4/0.1 mm(2)); P < 0.05. These effects no longer occurred in brains from pups treated with combined dexamethasone and pravastatin. Pravastatin alone had no effect on these variables.

CONCLUSION

Concomitant dexamethasone with statins in premature infants may be safer for the developing brain than dexamethasone alone in the treatment of chronic lung disease.

Fetal glucocorticoid exposure is associated with preadolescent brain development

BACKGROUND

Glucocorticoids play a critical role in normative regulation of fetal brain development. Exposure to excessive levels may have detrimental consequences and disrupt maturational processes. This may especially be true when synthetic glucocorticoids are administered during the fetal period, as they are to women in preterm labor. This study investigated the consequences for brain development and affective problems of fetal exposure to synthetic glucocorticoids.

METHODS

Brain development and affective problems were evaluated in 54 children (56% female), aged 6 to 10, who were full term at birth. Children were recruited into two groups: those with and without fetal exposure to synthetic glucocorticoids. Structural magnetic resonance imaging scans were acquired and cortical thickness was determined. Child affective problems were assessed using the Child Behavior Checklist.

RESULTS

Children in the fetal glucocorticoid exposure group showed significant and bilateral cortical thinning. The largest group differences were in the rostral anterior cingulate cortex (rACC). More than 30% of the rACC was thinner among children with fetal glucocorticoid exposure. Furthermore, children with more affective problems had a thinner left rACC.

CONCLUSIONS

Fetal exposure to synthetic glucocorticoids has neurologic consequences that persist for at least 6 to 10 years. Children with fetal glucocorticoid exposure had a thinner cortex primarily in the rACC. Our data indicating that the rACC is associated with affective problems in conjunction with evidence that this region is involved in affective disorders raise the possibility that glucocorticoid-associated neurologic changes increase vulnerability to mental health problems.

Cerebral artery signal transduction mechanisms: developmental changes in dynamics and Ca2+ sensitivity

As compared to the adult, the developing fetus and newborn infant are at much greater risk for dysregulation of cerebral blood flow (CBF), with complications such as intraventricular and germinal matrix hemorrhage with resultant neurologic sequelae. To minimize this dysregulation and its consequences presents a major challenge. Although in many respects the fundamental signal transduction mechanisms that regulate relaxation and contraction pathways, and thus cerebrovascular tone and CBF in the immature organism are similar to those of the adult, the individual elements, pathways, and roles differ greatly. Here, we review aspects of these maturational changes of relaxation/contraction mechanisms in terms of both electro-mechanical and pharmaco-mechanical coupling, their biochemical pathways and signaling networks. In contrast to the adult cerebrovasculature, in addition to attenuated structure with differences in multiple cytoskeletal elements, developing cerebrovasculature of fetus and newborn differs in many respects, such as a strikingly increased sensitivity to [Ca(2+)]i and requirement for extracellular Ca(2+) for contraction. In essence, the immature cerebrovasculature demonstrates both "hyper-relaxation" and "hypo-contraction". A challenge is to unravel the manner in which these mechanisms are integrated, particularly in terms of both Ca(2+)-dependent and Ca(2+)-independent pathways to increase Ca(2+) sensitivity. Gaining an appreciation of these significant age-related differences in signal mechanisms also will be critical to understanding more completely the vulnerability of the developing cerebral vasculature to hypoxia and other stresses. Of vital importance, a more complete understanding of these mechanisms promises hope for improved strategies for therapeutic intervention and clinical management of intensive care of the premature newborn.

Antenatal steroids and the IUGR fetus: are exposure and physiological effects on the lung and cardiovascular system the same as in normally grown fetuses?

Glucocorticoids are administered to pregnant women at risk of preterm labour to promote fetal lung surfactant maturation. Intrauterine growth restriction (IUGR) is associated with an increased risk of preterm labour. Hence, IUGR babies may be exposed to antenatal glucocorticoids. The ability of the placenta or blood brain barrier to remove glucocorticoids from the fetal compartment or the brain is compromised in the IUGR fetus, which may have implications for lung, brain, and heart development. There is conflicting evidence on the effect of exogenous glucocorticoids on surfactant protein expression in different animal models of IUGR. Furthermore, the IUGR fetus undergoes significant cardiovascular adaptations, including altered blood pressure regulation, which is in conflict with glucocorticoid-induced alterations in blood pressure and flow. Hence, antenatal glucocorticoid therapy in the IUGR fetus may compromise regulation of cardiovascular development. The role of cortisol in cardiomyocyte development is not clear with conflicting evidence in different species and models of IUGR. Further studies are required to study the effects of antenatal glucocorticoids on lung, brain, and heart development in the IUGR fetus. Of specific interest are the aetiology of IUGR and the resultant degree, duration, and severity of hypoxemia.

Oxidative stress in the developing brain: effects of postnatal glucocorticoid therapy and antioxidants in the rat

In premature infants, glucocorticoids ameliorate chronic lung disease, but have adverse effects on long-term neurological function. Glucocorticoid excess promotes free radical overproduction. We hypothesised that the adverse effects of postnatal glucocorticoid therapy on the developing brain are secondary to oxidative stress and that antioxidant treatment would diminish unwanted effects. Male rat pups received a clinically-relevant tapering course of dexamethasone (DEX; 0.5, 0.3, and 0.1 mg.kg⁻¹.day⁻¹), with or without antioxidant vitamins C and E (DEXCE; 200 mg.kg⁻¹.day⁻¹ and 100 mg.kg⁻¹.day⁻¹, respectively), on postnatal days 1–6 (P1–6). Controls received saline or saline with vitamins. At weaning, relative to controls, DEX decreased total brain volume (704.4±34.7 mm³ vs. 564.0±20.0 mm³), the soma volume of neurons in the CA1 (1172.6±30.4 µm³ vs. 1002.4±11.8 µm³) and in the dentate gyrus (525.9±27.2 µm³ vs. 421.5±24.6 µm³) of the hippocampus, and induced oxidative stress in the cortex (protein expression: heat shock protein 70 [Hsp70]: +68%; 4-hydroxynonenal [4-HNE]: +118% and nitrotyrosine [NT]: +20%). Dexamethasone in combination with vitamins resulted in improvements in total brain volume (637.5±43.1 mm³), and soma volume of neurons in the CA1 (1157.5±42.4 µm³) and the dentate gyrus (536.1±27.2 µm³). Hsp70 protein expression was unaltered in the cortex (+9%), however, 4-HNE (+95%) and NT (+24%) protein expression remained upregulated. Treatment of neonates with vitamins alone induced oxidative stress in the cortex (Hsp70: +67%; 4-HNE: +73%; NT: +22%) and in the hippocampus (NT: +35%). Combined glucocorticoid and antioxidant therapy in premature infants may be safer for the developing brain than glucocorticoids alone in the treatment of chronic lung disease. However, antioxidant therapy in healthy offspring is not recommended.

Postnatal betamethasone vs dexamethasone in premature infants with bronchopulmonary dysplasia: a pilot study

OBJECTIVE

As effects of glucocorticoids differ with respect to preparation, dose and duration, we hypothesized that a postnatal regimen of a low-dose, short-course betamethasone treatment had comparable efficacy and a better safety profile compared to the conventional high-dose, dexamethasone.

STUDY DESIGN

To test our hypothesis, we selected premature neonates with a birth weight <or=1000 g and a gestational age <or=29 weeks who were ventilated >10 postnatal days with an FiO(2)>0.4 and no ability to wean mechanical support for >or=3 consecutive days. These neonates either received twice daily dexamethasone 0.25 mg kg(-1) per dose intravenously for 3 days tapered to 0.125 mg kg(-1) per dose for 4 days (June 1999 to December 2000) or betamethasone 0.125 mg kg(-1) per day intramuscularly once per day for 3 days (January 2001 to December 2002).

RESULT

We found a significant reduction in FiO(2) after 3 days in both glucocorticoid treatment groups. There were no significant differences between the two treatment groups in the clinical parameters including decrease in FiO(2), oxygenation index, mean airway pressure and percent extubation. Duration of ventilation, number of oxygen days and length of hospital stay were comparable in the two groups. Of particular interest, the betamethasone group showed fewer adverse effects, such as poor weight gain and high blood glucose, than the dexamethasone group.

CONCLUSION

A short course of low-dose betamethasone has comparable efficacy and seemingly a better short-term safety profile compared to conventional dexamethasone treatment.

Betamethasone impairs cerebral blood flow velocities in very premature infants with severe chronic lung disease

OBJECTIVE

To assess betamethasone (BM) effects on the cerebral hemodynamics of neonates with severe chronic lung disease (CLD).

STUDY DESIGN

Intravenous BM was given once daily for 6 consecutive days to 12 infants (birth weight: 698 g [range, 650-884 g], gestational age: 25.3 weeks [range, 25-26.4 weeks]) at a postnatal age of 34 days (range, 28-36 days). Cerebral blood flow velocities (CBFVs) were recorded prospectively in the anterior cerebral artery (ACA) and the lenticulostriate artery (LSA) before, during, and after treatment, using Doppler flowmetry.

RESULTS

The decrease in systolic and diastolic velocities was maximum on the 5th day, reaching 32% (95% confidence interval [CI], 23%-42%) and 58% (95% CI, 39%-64%) from baseline in the ACA, and 44% (95% CI, 29%-50%) and 57% (95% CI, 33%-66%) in the LSA, respectively. The resistance index (RI) increased significantly in both arteries during treatment. Return to baseline values was observed after BM was stopped. The change in velocities and RI was independent of arterial blood gas and blood pressure variations.

CONCLUSIONS

BM decreased the CBFVs of premature infants, suggesting a vasoconstrictor effect in both superficial and deep arterial vessels. Caution is recommended when BM is used to treat preterm infants with severe CLD.

Regional cerebral blood flow and developmental outcome in cryptogenic West syndrome

PURPOSE

To elucidate the relation between alterations of regional cerebral blood flow (rCBF) by adrenocorticotropic hormone (ACTH) therapy and developmental outcomes of cryptogenic West syndrome.

METHODS

Quantitative measurement of rCBF, with autoradiography method using N-isopropyl-((123)I) p-iodoamphetamine single photon emission computed tomography before and after ACTH therapy, was performed on 17 infants with cryptogenic West syndrome. Regions of interest for rCBF were placed bilaterally in the cerebellum, the thalamus, the caudate nucleus, and the frontal, temporal, and occipital cortices. RCBFs and the alteration ratios calculated from rCBFs before and after ACTH therapy were compared between two groups: the normal and delayed groups, which were divided by developmental outcome at 2 years old.

RESULTS

RCBFs before the therapy were not different statistically between the normal and delayed groups, and between those groups and the control group also. RCBFs after ACTH therapy of the occipital, thalamic and cerebellar regions were different between the normal and delayed groups (p < 0.05). Alteration ratios were different between the normal and delayed groups, in all of the regions but the frontal region (p < 0.05).

CONCLUSIONS

This study showed the differences of rCBF response by ACTH therapy between the normal and delayed groups of cryptogenic West syndrome. The difference of rCBF alteration might be associated with maturation of the cerebrovascular system, or influence of corticotropin-releasing hormone regarding the brain-adrenal-axis.

Fetal cardiovascular, metabolic and endocrine responses to acute hypoxaemia during and following maternal treatment with dexamethasone in sheep

In sheep, direct fetal treatment with dexamethasone alters basal cardiovascular function and the cardiovascular response to acute hypoxaemia. However, in human clinical practice, dexamethasone is administered to the mother, not to the fetus. Hence, this study investigated physiological responses to acute hypoxaemia in fetal sheep during and following maternal treatment with dexamethasone in doses and at dose intervals used in human clinical practice. Under anaesthesia, 18 fetal sheep were instrumented with vascular and amniotic catheters, a carotid flow probe and a femoral flow probe at 118 days gestation (term ca 145 days). Following 6 days recovery at 124 days gestation, 10 ewes received dexamethasone (2 x 12 mg daily i.m. injections in saline). The remaining animals were saline-injected as age-matched controls. Two episodes of hypoxaemia (H) were induced in all animals by reducing the maternal F(IO2)for 1 h (H1, 8 h after the second injection; H2, 3 days after the second injection). In fetuses whose mothers received saline, hypoxaemia induced significant increases in fetal arterial blood pressure, carotid blood flow and carotid vascular conductance and femoral vascular resistance, significant falls in femoral blood flow and femoral vascular conductance and transient bradycardia. These cardiovascular responses were accompanied by a fall in arterial pH, increases in blood glucose and blood lactate concentrations and increased plasma concentrations of catecholamines. In fetuses whose mothers were treated with dexamethasone, bradycardia persisted throughout hypoxaemia, the magnitude of the femoral vasoconstriction, the glycaemic, lactacidaemic and acidaemic responses and the plasma concentration of neuropeptide Y (NPY) were all enhanced during H1. However, during H2, all of these physiological responses were similar to saline controls. In dexamethasone fetuses, the increase in plasma adrenaline was attenuated during H1 and the increase in carotid vascular conductance during hypoxaemia failed to reach statistical significance both during H1 and during H2. These data show that maternal treatment with dexamethasone in doses and intervals used in human obstetric practice modified the fetal cardiovascular, metabolic and endocrine defence responses to acute hypoxaemia. Furthermore, dexamethasone-induced alterations to these defences depended on whether the hypoxaemic challenge occurred during or following maternal dexamethasone treatment.