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Oxygen Supplementation to Stabilize Preterm Infants in the Fetal to Neonatal Transition: No Satisfactory Answer.

Torres-Cuevas I, Cernada M, Nuñez A, Escobar J, Kuligowski J, Chafer-Pericas C, Vento M - Front Pediatr (2016)

Bottom Line: Immediately after birth with the initiation of breathing, the lung expands and oxygen availability to tissue rises by twofold, generating a physiologic oxidative stress.However, both lung anatomy and function and the antioxidant defense system do not mature until late in gestation, and therefore, very preterm infants often need respiratory support and oxygen supplementation in the delivery room to achieve postnatal stabilization.Notably, interventions in the first minutes of life can have long-lasting consequences.

View Article: PubMed Central - PubMed

Affiliation: Neonatal Research Group, Health Research Institute La Fe , Valencia , Spain.

ABSTRACT
Fetal life elapses in a relatively low oxygen environment. Immediately after birth with the initiation of breathing, the lung expands and oxygen availability to tissue rises by twofold, generating a physiologic oxidative stress. However, both lung anatomy and function and the antioxidant defense system do not mature until late in gestation, and therefore, very preterm infants often need respiratory support and oxygen supplementation in the delivery room to achieve postnatal stabilization. Notably, interventions in the first minutes of life can have long-lasting consequences. Recent trials have aimed to assess what initial inspiratory fraction of oxygen and what oxygen targets during this transitional period are best for extremely preterm infants based on the available nomogram. However, oxygen saturation nomogram informs only of term and late preterm infants but not on extremely preterm infants. Therefore, the solution to this conundrum may still have to wait before a satisfactory answer is available.

No MeSH data available.


Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. The level of intervillous oxygen concentration varies along gestation. Studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen (PIVO2) has a median value around 18–20 mmHg, presumably to protect the embryo, which is highly sensitive to ROS. However, PIVO2 rises in the following weeks reaching a peak value (60 mmHg) around 14–16 weeks of gestation. Thenceforth, PIVO2 decreases slowly, reaching values of 45–48 mmHg at 36 weeks of gestation (9).
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Figure 3: Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. The level of intervillous oxygen concentration varies along gestation. Studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen (PIVO2) has a median value around 18–20 mmHg, presumably to protect the embryo, which is highly sensitive to ROS. However, PIVO2 rises in the following weeks reaching a peak value (60 mmHg) around 14–16 weeks of gestation. Thenceforth, PIVO2 decreases slowly, reaching values of 45–48 mmHg at 36 weeks of gestation (9).

Mentions: Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. Remarkably, the level of placental oxygen, as measured in the intervillous space, differs at different stages of gestation (Figure 3). The provision of an adequate amount of oxygen to the fetus shifts along gestation. Hence, levels considered normal early in pregnancy (8–14 weeks gestation) would be indicative of hypoxia in late pregnancy (>24 weeks gestation). Noteworthy, during the embryonic stage of development, the fetus is extremely sensitive to oxidative stress, and an environment of low oxygen is required for an adequate development. In the second half of pregnancy, the placenta will provide the fetus with higher amounts of oxygen and nutrients, allowing for an exponential increase in size and weight. Hence, studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen has a median value around 18–20 mmHg but rises steeply peaking at 60 mmHg around 14–16 weeks gestation, and thereafter decreases slowly reaching values of 45–48 mmHg at 36 weeks of gestation (20, 21).


Oxygen Supplementation to Stabilize Preterm Infants in the Fetal to Neonatal Transition: No Satisfactory Answer.

Torres-Cuevas I, Cernada M, Nuñez A, Escobar J, Kuligowski J, Chafer-Pericas C, Vento M - Front Pediatr (2016)

Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. The level of intervillous oxygen concentration varies along gestation. Studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen (PIVO2) has a median value around 18–20 mmHg, presumably to protect the embryo, which is highly sensitive to ROS. However, PIVO2 rises in the following weeks reaching a peak value (60 mmHg) around 14–16 weeks of gestation. Thenceforth, PIVO2 decreases slowly, reaching values of 45–48 mmHg at 36 weeks of gestation (9).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4835680&req=5

Figure 3: Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. The level of intervillous oxygen concentration varies along gestation. Studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen (PIVO2) has a median value around 18–20 mmHg, presumably to protect the embryo, which is highly sensitive to ROS. However, PIVO2 rises in the following weeks reaching a peak value (60 mmHg) around 14–16 weeks of gestation. Thenceforth, PIVO2 decreases slowly, reaching values of 45–48 mmHg at 36 weeks of gestation (9).
Mentions: Oxygenation of the fetus is clearly dependent on the partial pressure gradients between maternal blood, placental tissue, fetal blood, and tissue. Remarkably, the level of placental oxygen, as measured in the intervillous space, differs at different stages of gestation (Figure 3). The provision of an adequate amount of oxygen to the fetus shifts along gestation. Hence, levels considered normal early in pregnancy (8–14 weeks gestation) would be indicative of hypoxia in late pregnancy (>24 weeks gestation). Noteworthy, during the embryonic stage of development, the fetus is extremely sensitive to oxidative stress, and an environment of low oxygen is required for an adequate development. In the second half of pregnancy, the placenta will provide the fetus with higher amounts of oxygen and nutrients, allowing for an exponential increase in size and weight. Hence, studies performed in human fetuses have shown that before the 12th week of gestation, the intervillous partial pressure of oxygen has a median value around 18–20 mmHg but rises steeply peaking at 60 mmHg around 14–16 weeks gestation, and thereafter decreases slowly reaching values of 45–48 mmHg at 36 weeks of gestation (20, 21).

Bottom Line: Immediately after birth with the initiation of breathing, the lung expands and oxygen availability to tissue rises by twofold, generating a physiologic oxidative stress.However, both lung anatomy and function and the antioxidant defense system do not mature until late in gestation, and therefore, very preterm infants often need respiratory support and oxygen supplementation in the delivery room to achieve postnatal stabilization.Notably, interventions in the first minutes of life can have long-lasting consequences.

View Article: PubMed Central - PubMed

Affiliation: Neonatal Research Group, Health Research Institute La Fe , Valencia , Spain.

ABSTRACT
Fetal life elapses in a relatively low oxygen environment. Immediately after birth with the initiation of breathing, the lung expands and oxygen availability to tissue rises by twofold, generating a physiologic oxidative stress. However, both lung anatomy and function and the antioxidant defense system do not mature until late in gestation, and therefore, very preterm infants often need respiratory support and oxygen supplementation in the delivery room to achieve postnatal stabilization. Notably, interventions in the first minutes of life can have long-lasting consequences. Recent trials have aimed to assess what initial inspiratory fraction of oxygen and what oxygen targets during this transitional period are best for extremely preterm infants based on the available nomogram. However, oxygen saturation nomogram informs only of term and late preterm infants but not on extremely preterm infants. Therefore, the solution to this conundrum may still have to wait before a satisfactory answer is available.

No MeSH data available.