Fetal endocrine and renal responses to in utero ventilation and umbilical cord occlusion

Ogundipe, O. Anthony; Kullama, Linda K.; Stein, Howard; Nijland, Mark J.; Ervin, M. Gore; Padbury, Jim; Ross, Michael G.

doi:10.1016/0002-9378(93)90422-f

Cited by 24 publications

(6 citation statements)

References 28 publications

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“…Therefore, the increase in the pulmonary vascular response to alveolar ventilation at birth observed after antenatal GC could be explained at least in part by an increase in NO production or by an increase in vascular response to NO. Otherwise, mechanical ventilation is also known to cause a large release of catecholamines and especially norepinephrine [11] . Interestingly, Smolich and coworkers reported that the lungs contribute about twofi fths of the total body norepinephrine spillover into the circulation [12,13] .…”

Section: Discussionmentioning

confidence: 99%

Effects of Antenatal Glucocorticoids on Circulatory Adaptation at Birth in the Ovine Fetus

Houfflin‐Debarge

Deruelle²,

Jaillard³

et al. 2005

Neonatology

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Objective: Adaptation to extra-uterine life requires dramatic increase in pulmonary blood flow. Mechanisms that induce pulmonary vasodilatation at birth are incompletely understood but include alveolar ventilation, increase in PaO₂, and production of vasoactive mediators. We hypothesized that antenatal glucocorticoids (GC) increase pulmonary vasodilatation to birth-related stimuli. Study Design: To test this hypothesis, we studied the pulmonary hemodynamic response at birth to mechanical ventilation with low (<10%) and then with high (100%) FiO₂ in chronically prepared late-gestation fetal lambs treated or not by antenatal maternal steroids. Results: Basal mean aortic and pulmonary artery pressure (PAP), left pulmonary blood flow, pulmonary vascular resistance (PVR), and blood gas were similar between control and dexamethasone-treated animals (GC group). During mechanical ventilation with low FiO₂, mean PVR decreased by 40% in the control group (from 0.44 ± 0.01 to 0.25 ± 0.01 mm Hg/ml/min) and by 60% in the GC group (from 0.44 ± 0.02 to 0.19 ± 0.02 mm Hg/ml/min) (p < 0.01). When subsequently ventilated with 100% O₂, there was no difference in PVR decrease between groups (0.15 ± 0.02 mm Hg/ml/min in the GC group vs. 0.14 ± 0.01 mm Hg/ml/min in the control group). Conclusion: Antenatal GC enhance pulmonary vasodilatation induced by alveolar ventilation at birth but do not alter the pulmonary vascular response to O₂. We speculate that antenatal steroids exposure improve adaptation at birth through acceleration of both parenchymal and vascular lung maturation.

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Section: Discussionmentioning

confidence: 99%

Effects of Antenatal Glucocorticoids on Circulatory Adaptation at Birth in the Ovine Fetus

Houfflin‐Debarge

Deruelle²,

Jaillard³

et al. 2005

Neonatology

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“…By occluding the ductus, Giraud et al (1995) reported a larger increase in Pa,Oµ (from about 13·5 to 33 mmHg) with in utero gas ventilation. Ogundipe et al (1993) ventilated in utero lambs and found an even bigger change in Pa,Oµ from 18 ± 1 to 86 ± 29 mmHg but this required cord occlusion.…”

Section: Adequacy Of Oxygenationmentioning

confidence: 94%

The Effects of in Vivo Pulmonary Oxygenation on Lung Liquid Production in Near‐Term Fetal Sheep

Round

Junor

Gallagher

et al. 1999

Experimental Physiology

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SUMMARY Lung liquid (LL) is secreted into the fetal lung lumen, but it must be rapidly absorbed at birth to allow air breathing. In vitro studies have implicated oxygen as a possible factor causing the switch from secretion to absorption of lung liquid at birth. We developed a technique of oxygenating the fetal lung using liquid ventilation with haemoglobin (Hb) solutions in chronically catheterized fetal lambs (129‐140 days gestation; term, 147 days). In some experiments 2,3‐diphosphoglycerate (DPG) was added to increase oxygen delivery. LL secretion rate (Jv) was measured using an indicator dilution method. Eighteen fetuses were divided into four groups and ventilated with liquid under the following conditions: (i) Hb with oxygen, (ii) Hb without oxygen, (iii) Hb with DPG and oxygen and (iv) Hb with DPG without oxygen. There was a significant rise (2·6 mmHg, P < 0·02) in fetal arterial PO2 in group iii, but in none of the other groups. In the first 3 h of liquid ventilation there was no difference in Jv between the groups. In group i, during hours 4‐6 of liquid ventilation, there was a significant rise in secretion rate from 2·25 ± 0·88 to 3·74 ± 0·85 ml h−1 kg−1 (P < 0·001). In group iii, when comparing Jv in the first 3 h of liquid ventilation with that in the following 3 h period of liquid ventilation, a strong trend towards reduction in secretion was observed, falling from 3·03 ± 0·65 to 0·74 ± 0·92 ml h−1 kg−1 (three of the four experiments showed a significant decrease in Jv in hours 4‐6). These experiments indicate that oxygen delivered to the fetus using liquid ventilation with haemoglobin solutions leads to increased LL secretion when oxygen delivery is small, and suggest there is a decrease in secretion with greater oxygen delivery to the lung.

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“…Because epinephrine levels correlate most consistently with measures of psychologic distress and pain during labor, efforts to ameliorate maternal stress through holistic interventions are in the interest of the fetus, as well as the mother. Normal labor and vaginal birth are consistently associated with elevated cord concentrations of norepinephrine and epinephrine in the neonate (Ogundipe et al, 1993). Fetal sheep data suggest that increasing levels of thyroid hormone in the final days of gestation prepare the heart to respond to this catecholamine surge by causing a dramatic increase in the number of myocardial beta-adrenergic receptors (Long & Henry, 1992).…”

Section: Catecbolaminesmentioning

confidence: 99%

Parturition and Fetal Adaptation

Lowe¹,

Reiss

1996

Journal of Obstetric, Gynecologic & Neonatal Nursing

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Fetal endocrine and renal responses to in utero ventilation and umbilical cord occlusion

Cited by 24 publications

References 28 publications

Effects of Antenatal Glucocorticoids on Circulatory Adaptation at Birth in the Ovine Fetus

Effects of Antenatal Glucocorticoids on Circulatory Adaptation at Birth in the Ovine Fetus

The Effects of in Vivo Pulmonary Oxygenation on Lung Liquid Production in Near‐Term Fetal Sheep

Parturition and Fetal Adaptation

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