Neonatology
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Inhaled nitric oxide (iNO) is effective in term infants with hypoxic respiratory failure. The pathophysiology of respiratory failure and the potential risks of iNO differ substantially in preterm infants, necessitating study in this population. ⋯ Fourteen randomized controlled trials of iNO therapy in preterm infants were found. The trials have been grouped post hoc into three categories depending on entry criteria: entry in the first 3 days of life based on oxygenation criteria, routine use in preterm babies with pulmonary disease, and later enrolment based on an increased risk of BPD. No overall analyses were performed. Nine trials of early rescue treatment of infants based on oxygenation criteria demonstrated no significant effect of iNO on mortality or BPD. Three studies with routine use of iNO in infants with pulmonary disease also demonstrated no significant reduction in death or BPD [typical RR 0.93 (95% CI 0.86-1.01)] although this small effect approached significance. Later treatment with iNO based on the risk of BPD (two trials) demonstrated no significant benefit for this outcome in analyses which are possible using summary data. There is no clear effect of iNO on the frequency of all grades of IVH or of severe IVH. Early rescue treatment was associated with a non-significant 20% increase in severe IVH. No effect on the incidence of neurodevelopmental impairment was found.
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In this review oxygenation and hyperoxic injury of newborn infants are described through molecular and genetic levels. Protection and repair mechanisms that may be important for a new understanding of oxidative stress in the newborn are discussed. The research summarized in this article represents a basis for the reduced oxygen supplementation and oxidative load of newborn babies, especially since the turn of the century. ⋯ Today, term babies should be resuscitated with air rather than 100% oxygen and very and extremely low birth weight infants in need of stabilization or resuscitation at birth should be administered initially 21-30% oxygen and the level should be titrated according to the response, preferably measured by pulse oximetry. In the postnatal period the oxygen saturation should be targeted low <95%; however, saturations between 85 and 89% seem to increase mortality. The optimal oxygen saturation target for these infants postnatally is still unknown.
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Intermittent fetal heart rate (FHR) monitoring during labor using an acoustic stethoscope is the most frequent method for fetal assessment of well-being in low- and middle-income countries. Evidence concerning reliability and efficacy of this technique is almost nonexistent. ⋯ Intermittent detection of an absent or abnormal FHR using a fetal stethoscope is associated with FSB, increased need for neonatal resuscitation, BA, and neonatal death in a limited-resource setting. The likelihood of an abnormal FHR is magnified with labor complications.
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The perfusion index (PI), derived from the pulse oximetry signal, has been shown to be an accurate predictor for identifying high illness severity in neonates. The plethysmographic variability index (PVI) is a measure of the dynamic change in PI occurring during a complete respiratory cycle. ⋯ Our findings suggest: (1) evaluation of PVI values is an easily applicable, noninvasive procedure for monitoring early postnatal respiratory changes in newborns, and (2) the feasibility of a noninvasive pulse-oximeter postnatal screening for early identification of adverse neonatal cardiorespiratory outcomes.
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Review
Mechanisms of injury to the preterm lung and airway: implications for long-term pulmonary outcome.
Despite changes in the epidemiology of bronchopulmonary dysplasia (BPD), longer-term morbidity, particularly in the form of airway dysfunction, remains a substantial problem in former preterm infants. The stage for this respiratory morbidity may begin as early as the transition from fetal to neonatal life. Newer therapeutic approaches for BPD should be directed toward minimizing this longer-term respiratory morbidity. Neonatal animal models focused primarily on hyperoxic exposure may provide important insights into the pathogenesis of longer-term airway hyperreactivity in this population.