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Identifying perinatal hypoxic-ischemic/asphyxial events in preterm infants is more challenging compared with infants ≥36 weeks’ gestation.
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For the more mature preterm infant, extrapolation of criteria used in infants ≥36 weeks’ gestation to identify perinatal hypoxia-ischemia may be feasible.
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For the extreme preterm infant, identification of perinatal hypoxia-ischemia that is linked to early childhood outcome is difficult given the many morbidities of prematurity; this will limit a targeted
Birth Asphyxia and Hypoxic-Ischemic Brain Injury in the Preterm Infant
Section snippets
Key points
Terminology
In clinical practice, the terms hypoxia-ischemia and asphyxia are often used interchangeably. Technically there are important differences. Hypoxia is a low content of oxygen in the blood, whereas ischemia represents a reduction in tissue blood flow. Ischemia in turn can be partial or complete in extent, and can be focal or global in distribution. Hypoxia and ischemia are often combined because each component may result in the other. In contrast, asphyxia indicates an impairment of gas exchange
Criteria for the diagnosis of hypoxia-ischemia
For infants ≥36 weeks’ gestation, a tiered set of criteria have emerged to diagnose hypoxia-ischemia shortly after birth. This includes identification of an event that can impair fetal gas exchange or objective evidence of altered fetal gas exchange. The newborn in turn needs to manifest biologic effects of impaired gas exchange. The latter is done by demonstrating the presence of encephalopathy because links between perinatal hypoxia-ischemia/asphyxia and childhood neurodevelopmental deficits
Term Infants
The neuropathology of hypoxic-ischemic/asphyxial brain injury differs as a function of gestational age. Hypoxic-ischemic injury among term infants is dominated by selective neuronal necrosis, followed by parasagittal cerebral injury and least commonly focal ischemic necrosis in a vascular distribution.19 The distribution of these lesions follow patterns observed in asphyxial brain injury of the near-term monkey fetus.31, 32 With total or complete asphyxia, the neuropathology primarily affected
Term Infants
Imaging of hypoxic-ischemic brain injury among term infants is consistent with patterns of neuropathology. MRI is the imaging mode of choice for selective neuronal necrosis and detects abnormal signal in the basal ganglia, thalami, and posterior limb of the internal capsule, loss of gray-white matter differentiation in the cerebral hemispheres, and highlighting of the cerebral cortex (Fig. 3). Miller and colleagues46 reported on MRIs acquired from 173 term infants (median age, 6 days) with
Incidence of hypoxia-ischemia/asphyxia among preterm infants
Because it is difficult to identify hypoxia-ischemia/asphyxia among preterm infants at or soon after birth, studies that examined the incidence of these events among preterm infants have focused on more mature gestational ages. Salhab and Perlman20 reported moderate and severe encephalopathy among infants 31 to 36 weeks’ gestation with severe fetal acidemia; the incidence of encephalopathy was 1.4 per 1000 live births. Schmidt and Walsh63 reported the incidence of hypoxic-ischemic
Is therapeutic hypothermia a viable treatment option for preterm infants?
Therapeutic hypothermia is the only therapy demonstrated to be efficacious for hypoxic-ischemic/asphyxial brain injury among infants ≥36 weeks’ gestation based on 5 randomized trials. One of these trials and a smaller pilot trial enrolled infants ≥35 weeks.5, 65 Based on personal communication with the investigators, only 7 infants born between 350 and 356 weeks were randomized in these 2 trials. The Committee on the Fetus and Newborn of the American Academy of Pediatrics concluded in a report
Neuroprotection for hypoxia-ischemia/asphyxia in extreme preterm infants
There are multiple reasons why neuroprotective strategies for extreme preterm infants will differ from moderate and late preterm infants. Hypoxic-ischemic events are probably most frequent around the time of birth or in the first days after birth coincident with serious morbidities of prematurity and associated hemodynamic instability. Even with this knowledge, it is difficult to determine the impact of putative hypoxic-ischemic events because sensitive and specific markers of brain injury are
Summary
Birth asphyxia is a modifiable process, as demonstrated by randomized trials of therapeutic hypothermia in infants ≥36 weeks’ gestation with evidence of hypoxia-ischemia/asphyxia. Extending investigation to preterm infants is well justified; however, there are many challenges. Identifying perinatal hypoxic-ischemic/asphyxial events in preterm infants is more challenging compared with infants ≥36 weeks’ gestation. For the more mature preterm infant, extrapolation of criteria used in infants
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Comparative study of neonatal brain injury fetuses using machine learning methods for perinatal data
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2021, Neurobiology of Learning and MemoryCitation Excerpt :In last years, there is a great discussion about ischemia and hypoxia as determinants of brain injury in preterm infants (Gilles, Gressens, Dammann, & Leviton, 2018), with some authors indicating that the evidence for ischemia and hypoxia is low. Even considering that in the majority of preterm children hypoxia and ischemia are not a main contributor to brain damage, it is undeniable that hypoxia and ischemia are, at least in part, responsible for brain injury in some preterm infants (Laptook, 2016). There is a growing amount of literature about hypoxic-ischemic encephalopathy in preterm newborns and some authors have discussed about the efficacy of hypothermia in preterm newborns (Herrera et al., 2018; Rao et al., 2017).
Therapeutic hypothermia for preterm infants 34–35 weeks gestational age with neonatal encephalopathy
2024, Journal of PerinatologyEmerging therapeutic strategies in hypoxic-ischemic encephalopathy: a focus on cognitive outcomes
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Disclosure: The author has no financial relationship with a commercial entity producing health-care related products and/or services.