Additional Clinical Aspects of Developmental Physiology and Clinical Care

Longo, Lawrence D.

doi:10.1007/978-1-4939-7483-2_20

Cited by 2 publications

(2 citation statements)

References 192 publications

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“…Exposure of pregnant ewes to a reduced fraction of inspired oxygen produced a sustained reduction in fetal femoral arterial

P_{{normalO}_{2}}

to 10–12 mmHg between 0.8 and 0.9 of gestation. This represents an estimated 50% reduction in the normal oxygenation values of the fetal umbilical artery, 20 mmHg (Longo, ). Reductions of a similar or greater magnitude have been measured through sampling the umbilical vein in growth‐restricted human fetuses at comparable points in gestation (Soothill et al .…”

Section: Discussionmentioning

confidence: 99%

Altered autonomic control of heart rate variability in the chronically hypoxic fetus

Shaw

Allison

Itani

et al. 2018

The Journal of Physiology

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Key points Fetal heart rate variability (FHRV) has long been recognised as a powerful predictor of fetal wellbeing, and a decrease in FHRV is associated with fetal compromise. However, the mechanisms by which FHRV is reduced in the chronically hypoxic fetus have yet to be established.The sympathetic and parasympathetic influences on heart rate mature at different rates throughout fetal life, and can be assessed by time domain and power spectral analysis of FHRV.In this study of chronically instrumented fetal sheep in late gestation, we analysed FHRV daily over a 16 day period towards term, and compared changes between fetuses of control and chronically hypoxic pregnancy.We show that FHRV in sheep is reduced by chronic hypoxia, predominantly due to dysregulation of the sympathetic control of the fetal heart rate. This presents a potential mechanism by which a reduction in indices of FHRV predicts fetuses at increased risk of neonatal morbidity and mortality in humans.Reduction in overall FHRV may therefore provide a biomarker that autonomic dysregulation of fetal heart rate control has taken place in a fetus where uteroplacental dysfunction is suspected. AbstractAlthough fetal heart rate variability (FHRV) has long been recognised as a powerful predictor of fetal wellbeing, the mechanisms by which it is reduced in the chronically hypoxic fetus have yet to be established. In particular, the physiological mechanism underlying the reduction of short term variation (STV) in fetal compromise remains unclear. In this study, we present a longitudinal study of the development of autonomic control of FHRV, assessed by indirect indices, time domain and power spectral analysis, in normoxic and chronically hypoxic, chronically catheterised, singleton fetal sheep over the last third of gestation. We used isobaric chambers able to maintain pregnant sheep for prolonged periods in hypoxic conditions (stable fetal femoral arterial PnormalO2 10–12 mmHg), and a customised wireless data acquisition system to record beat‐to‐beat variation in the fetal heart rate. We determined in vivo longitudinal changes in overall FHRV and the sympathetic and parasympathetic contribution to FHRV in hypoxic (n = 6) and normoxic (n = 6) ovine fetuses with advancing gestational age. Normoxic fetuses show gestational age‐related increases in overall indices of FHRV, and in the sympathetic nervous system contribution to FHRV (P < 0.001). Conversely, gestational age‐related increases in overall FHRV were impaired by exposure to chronic hypoxia, and there was evidence of suppression of the sympathetic nervous system control of FHRV after 72 h of exposure to hypoxia (P < 0.001). This demonstrates that exposure to late gestation isolated chronic fetal hypoxia has the potential to alter the development of the autonomic nervous system control of FHRV in sheep. This presents a potential mechanism by which a reduction in indices of FHRV in human fetuses affected by uteroplacental dysfunction can predict fetuses at increased risk.

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“…Exposure of pregnant ewes to a reduced fraction of inspired oxygen produced a sustained reduction in fetal femoral arterial

P_{{normalO}_{2}}

Section: Discussionmentioning

confidence: 99%

Altered autonomic control of heart rate variability in the chronically hypoxic fetus

Shaw

Allison

Itani

et al. 2018

The Journal of Physiology

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“…Thus, many of the factors involved in the birth process are not yet fully understood. Asphyxia, umbilical cord occlusion or the rise in PaO2 with the first postnatal breath may be involved [76,77], although neither the afferent input from the carotid sinus nerve [78] nor the interruption of umbilical circulation [79] seem to play a role in this process.…”

Section: Fetal Respiratory Distressmentioning

confidence: 99%

Effects of Gestational Intermittent Hypoxia on the Respiratory System: A Tale of the Placenta, Fetus and Developing Offspring

Valverde-Perez,

Olea,

Rocher

et al. 2024

Preprint

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Obstructive sleep apnea (OSA) is a common sleep disorder that is associated with a wide variety of health conditions, including cardiovascular, cerebrovascular, metabolic, neoplastic, and neurocognitive manifestations. OSA is mainly characterized by repeated upper airway obstructions during sleep that cause episodes of chronic intermittent hypoxia (IH), resulting in tissue hypoxia-reoxygenation. Decreased arterial oxygen pressure (PaO2) and hemoglobin saturation (SatO2) stimulate reflex responses to overcome the obstruction. The prevalence of OSA is significant worldwide, particularly in women during pregnancy, due to the physiological changes associated with this stage of life, especially in its later stages. It is associated with an increased risk of hypertension, pre-eclampsia and diabetes, among others. OSA during pregnancy can interfere with normal fetal development and is associated with growth retardation, preterm birth, or low term weight. Carotid body stimulation and hypoxia-reoxygenation episodes contribute to cardiovascular disease and oxidative stress, that can harm both, mother and the fetus, even into the adulthood. Because gestational intermittent hypoxia (GIH) is the hallmark of OSA in pregnancy, this review examines the impact of GIH on maternal, fetal, and offspring respiratory outcomes. Most adverse outcomes can be prevented by continuous positive airway pressure (CPAP) therapy and lifestyle changes if gestational OSA is detected early and treated appropriately.

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Additional Clinical Aspects of Developmental Physiology and Clinical Care

Cited by 2 publications

References 192 publications

Altered autonomic control of heart rate variability in the chronically hypoxic fetus

Altered autonomic control of heart rate variability in the chronically hypoxic fetus

Effects of Gestational Intermittent Hypoxia on the Respiratory System: A Tale of the Placenta, Fetus and Developing Offspring

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