Placental oxygen transfer reduces hypoxia/reoxygenation swings in fetal blood in a sheep model of gestational sleep apnea

Abstract

AIM: Obstructive sleep apnea (OSA), characterized by events of hypoxiareoxygenation, is highly prevalent in pregnancy, negatively affecting the gestation process and particularly the fetus. Whether the consequences of OSA on the fetus and offspring are mainly caused by systemic alterations in the mother or by direct effect of intermittent hypoxia in the fetus is unknown. In fact, how apnea-induced hypoxemic swings in OSA are transmitted across the placenta remains to be investigated. The aim of this study was to test the hypothesis, based on a theoretical background on the dampening effect of oxygen transfer in the placenta, that oxygen partial pressure (PO 2 ) swings resulting from obstructive apneas mimicking OSA are mitigated in the fetal circulation. METHODS: To this end, 4 anesthetized ewes close to term pregnancy were subjected to obstructive apneas consisting of 25-s airway obstructions. Real time PO 2 was measured in the maternal carotid artery and in the umbilical vein using fast-response fiberoptic oxygen sensors. RESULTS: The amplitude of PO 2 swings in the umbilical vein were considerably smaller (3.1±1.0 vs. 21.0±6.1 mmHg (m±SE); p<0.05). Corresponding estimated swings in fetal and maternal oxyhemoglobin saturation tracked PO 2 swings. CONCLUSION: This study provides novel insights into fetal oxygenation in a model of gestational OSA, and highlights the importance of further understanding the impact of sleep-disordered-breathing on fetal and offspring development.

The relationship between maternal anemia and umbilical cord oxygen content at delivery

“…The association between maternal anemia and higher UV O 2 content is biologically plausible and may in fact be attributed to an adaptive mechanism in pregnancy physiology that causes easier unloading of O 2 to the fetus. This hypothesis has been demonstrated by Paulone et al 24 26,27 In fact, the rate of O 2 consumption during pregnancy increases up to 20% compared with nonpregnant individuals to accommodate the O 2 demands of the placenta and fetus. 28 Compensatory adaptations in placental physiology may also play a role.…”

ERS International Congress, Madrid, 2019: highlights from the Sleep and Clinical Physiology Assembly

“…Other interesting study showed how intermittent hypoxia are transmitted to the fetus in a sleep apnoea ewe model. ALMENDROS et al [39] subjected pregnant ewes to intermittent hypoxia and measured oxygen partial pressure simultaneously on the femoral artery of the mother and in the umbilical vein. Finally, the work from OP DE BEECK et al [40] showed that higher loop gain is associated with a reduced upper airway stimulation.…”

“…A lmendros et al . [ 39 ] subjected pregnant ewes to intermittent hypoxia and measured oxygen partial pressure simultaneously on the femoral artery of the mother and in the umbilical vein. Finally, the work from O p de B eeck et al .…”

Aspectos comportamentais e morfo-fisiológicos das trocas gasosas de >i<Phrynops geoffroanus>/i< (Wagler, 1830) (Testudines: Chelidae)

“…As cores representam: preto, normoxia aérea e aquática (bursa cloacal); verde, anóxia aérea e normoxia aquática; amarelo, anoxia aérea e aquática, (bursa cloacal); azul, anoxia aérea e hiperóxia aquática (bursa cloacal) e; vermelho, anoxia aérea e hiperóxia aquática (cavidade bucofaringeal) . Fonte: Cordeiro, 2019 (FORMENTI et al, 2015;ALMENDROS et al, 2019).…”