Target oxygen levels in preterm neonates

Abstract

To achieve postnatal adaptation newly born infant need to aerate the lungs, reduce pulmonary vascular resistance, and initiate oxygen and carbon dioxide exchange. The cornerstone of newborn resuscitation resides therefore in the establishment of a functional residual capacity and an adequate oxygenation. Recent guidelines have established guidelines concerning oxygen supplementation in preterm infants in the delivery room (DR); however, they are vague and unspecific. Herewith, we will address available information regarding the use of oxygen supplementation in the DR in preterm infants to satisfactorily overcome postnatal adaptation. Introduction: Resuscitation of the newborn is considered the most frequent and one of the most stressful interventions in the neonatal period. In order to successfully resuscitate depressed newborn infants birth attendants have to be adequately trained and the equipment employed has to meet specific standards of quality [1]. In 2010 the International Liaison Committee on Resuscitation (ILCOR) released new recommendations for the use of oxygen supplementation during resuscitation [2]. However, the precise management of oxygen in the DR especially in preterm infants still poses a great deal of uncertainty to care givers. Physiologic changes in oxygenation in the fetal to neonatal transition: Fetal to neonatal transition causes cardio-respiratory changes that lead to an abrupt rise in paO2 from 3.1 kPa to 9.3 kPa; however, as a consequence a burst of reactive oxygen species (ROS) will be generated. Conspicuously, ROS under physiologic circumstances act as signaling molecules modulating maturation of specific metabolic pathways. On the contrary under hypoxic ischemic conditions an excess of oxygen upon re-oxygenation will cause oxidative damage and increased mortality [3]. Conspicuously, the expression of antioxidant enzymes only takes place in the last weeks of gestation paralleling surfactant production. Therefore, babies born prematurely are at high risk of developing oxidative stress associated conditions [3]. Moreover, ROS in the presence of nitric oxide will cause nitrosative stress predisposing preterm infants to pulmonary vasoconstriction and pulmonary hypertension [4]. Prematurity also predisposes to chronic conditions such as bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP) or intra-periventricular hemorrhage (IVP) [3]. Interestingly, maturation is gender related and the use of antenatal steroids enhances antioxidant enzymes’ activation thus increasing postnatal adaptability of preterm infants [5]. Oxygen supplementation in the delivery room: What is the normal range of oxygen saturation in the first minutes of life? Preductal pulse oximetry provides reliable values of pre-ductal arterial oxygen saturation (SpO2) in 60–90 seconds after birth. In term infants preductal SpO2 rises from ~50% to >90% in the first 5 min after birth. In preterm infants time to achieving SpO2 plateau ~90% takes almost 10–15 min [6] as reflected in Dawson’s nomogram [6] (see Figure 1).