Oxygen Supplementation During Preterm Stabilization and the Relevance of the First 5 min After Birth

Abstract

Fetal to neonatal transition entails cardiorespiratory, hemodynamic, and metabolic changes coinciding with the switch from placental to airborne respiration with partial pressures of oxygen of 4-5 kPa in utero raising to 8-9 kPa ex utero in few minutes. Preterm infants have immature lung and antioxidant defense system. Very preterm infants (<32 weeks' gestation) frequently require positive pressure ventilation and oxygen to establish lung aeration, a functional residual capacity, and overcome a tendency toward hypoxemia and bradycardia in the first minutes after birth. Recent studies have shown that prolonged bradycardia (heart rate <100 beats per minute) and/or hypoxemia (oxygen saturation <80%) are associated with increased mortality and/or intracranial hemorrhage. However, despite the accumulated evidence, the way in which oxygen should be supplemented in the first minutes after birth still has not yet been clearly established. The initial inspired fraction of oxygen and its adjustment within a safe arterial oxygen saturation range measured by pulse oximetry that avoids hyper-or-hypoxia is still a matter of debate. Herewith, we present a current summary aiming to assist the practical neonatologist who has to aerate the lung and establish an efficacious respiration in very preterm infants in the delivery room.

A critical appraisal of tools for delivery room assessment of the newborn infant

“…Transition from fetal to neonatal condition is the most complex physiologic adaptation in life as it is associated with rapid cardiorespiratory, hemodynamic, and metabolic changes. 1,2 Whereas the majority of newborns adapt without significant problems, up to 15 % of all newborns need some medical support during their transitional period. To define infants needing support, Virginia Apgar developed a scoring system to assess postnatal condition by converting simple clinical observations into numerical data.…”

Clinical Parameters in the First 5 Minutes after Birth Have a Predictive Value for Survival of Extremely Preterm Infants

“…Following a few intense breaths immediately after birth, the arterial partial pressure of oxygen undergoes a rapid increase that stabilizes approximately 10 minutes after birth. 1 However, in extremely preterm infants (<28 weeks' gestation), postnatal adaptation is hampered by a series of factors inherent to their immaturity. The most relevant factors are deficient surfactant synthesis by type II pneumocytes, weak respiratory drive that leads to periodic breathing or even apneic episodes, low inherent cardiac contractility, limited ability to adjust cardiac output, low tolerance to systemic vascular resistance, and persistence of fetal shunts.…”

“…Postnatal stabilization of the newborn infant comprises a series of hemodynamic, cardiorespiratory, and metabolic changes that occur in an orderly manner to allow the neonate to switch from placental to lung respiration and from a dependent to an independent circulation. Following a few intense breaths immediately after birth, the arterial partial pressure of oxygen undergoes a rapid increase that stabilizes approximately 10 minutes after birth 1 . However, in extremely preterm infants (<28 weeks' gestation), postnatal adaptation is hampered by a series of factors inherent to their immaturity.…”