Pediatric research
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Comparative Study
CBF reactivity in hypotensive and normotensive preterm infants.
Perinatal distress in the preterm neonate, and the consequent loss of cerebrovascular autoregulation, has been implicated in the pathogenesis of neonatal cerebral lesions. A component of this distress is thought to be hypotension. We examined the autoregulatory capacity of hypotensive and normotensive infants using the 133Xe technique to measure cerebral blood flow. ⋯ The CO2-CBF reactivity (95%CI) of the normotensive and hypotensive infants was 11.1% (6.8% to 15.5%)/KPa deltaPaCO2 and 4.1% (-5.0% to 14.1%)/KPa deltaPaCO2. The implications of these calculated CBF reactivities is that normotensive infants may have intact autoregulation but with a diminished response to fluctuations in PaCO2. The hypotensive infants appear to have attenuated or absent autoregulation with little or no response in CBF to changes in PaCO2.
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The hypothesis was tested that treatment with allopurinol, a xanthine oxidase inhibitor, or deferoxamine, a chelator of nonprotein-bound iron, preserved cerebral energy metabolism, attenuated development of edema, and improved histologic outcome in the newborn piglet at 24 h after hypoxia-ischemia. Thirty-two newborn piglets were subjected to 1 h of hypoxia-ischemia by occluding both carotid arteries and reducing the fraction of inspired oxygen; five newborn piglets served as sham-operated controls. The depth of hypoxia-ischemia was controlled by phosphorous magnetic resonance spectroscopy. ⋯ Water T2 values were significantly increased at 24 h after hypoxia-ischemia in cerebral cortex, thalamus, and striatum of vehicle-treated piglets, but not in allopurinol- and deferoxamine-treated piglets. No differences in caspase-3 activity, histologic outcome, or TUNEL-labeling were demonstrated between the three treatment groups. We suggest that allopurinol and deferoxamine may have an additional value in the treatment of perinatal hypoxia-ischemia with other neuroprotective agents or in combination with hypothermia.
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Brain-specific proteins have been used to detect cerebral injury after birth asphyxia. Previous investigations suggest that serum protein S-100beta, brain-specific creatine kinase (CK-BB), and neuron-specific enolase (NSE) are capable of identifying patients with a risk of developing hypoxic-ischemic encephalopathy. Whether detection of elevated serum concentrations of these proteins reflects long-term neurodevelopmental impairment remains to be investigated. ⋯ Neurodevelopmental follow-up examinations were performed at 20 mo of age using the German revision of the Griffiths scales for developmental assessment. Elevated concentrations of serum protein S-100beta, NSE, and CK-BB within 24 h after asphyxia did not correlate with long-term neurodevelopmental delay. We conclude that serum protein S-100beta, NSE, and CK-BB, sampled on the first day of life, is of limited value in predicting severe brain damage after birth asphyxia.
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The neuroprotective effect of hypothermia instituted after resuscitation from asphyxic cardiac arrest has not been studied in immature brain, particularly in a large animal model with recovery periods greater than 4 d. Moreover, protection from severe hypoxia seen with 3 h of hypothermia was reported to be lost when hypothermic duration was extended to 24 h in unsedated piglets, in contrast to the neuroprotection reported by 72 h of intrauterine head cooling in fetal sheep. Piglets (5-7 postnatal days) were subjected to asphyxic cardiac arrest followed by 24 h of either hypothermia (34 degrees C) or normothermia (38.5-39 degrees C). ⋯ Ischemic cytopathology affected 60 +/- 12% of neurons in putamen of normothermic animals compared with 9 +/- 6% in hypothermic animals at 1 d of recovery without rewarming. At 11 d of recovery from hypoxia-ischemia, the density of viable neurons (neuron profiles/mm2) in putamen was markedly reduced in normothermic animals (81 +/- 40) compared with hypothermic animals (287 +/- 22), which was the same as in sham normothermic (271 +/- 21), sham hypothermic (288 +/- 46) and naïve animals (307 +/- 51). These data demonstrate that 24 h of hypothermia at 34 degrees C with sedation and muscle relaxation after asphyxic cardiac arrest prevents necrotic striatal neuronal cell death in immature brain before rewarming, and that the effect is sustained at 11 d after injury without deleterious side effects.
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Late-onset neonatal sepsis is a significant cause of morbidity and mortality, and early detection could prove beneficial. Previously, we found that abnormal heart rate characteristics (HRC) of reduced variability and transient decelerations occurred early in the course of neonatal sepsis and sepsis-like illness in infants in a single neonatal intensive care unit (NICU). We hypothesized that this finding can be generalized to other NICUs. ⋯ In the derivation cohort, there were 155 episodes of sepsis and sepsis-like illness in 101 infants, and in the validation cohort, there were 118 episodes in 93 infants. In the validation cohort, the HRC index 1) showed highly significant association with impending sepsis and sepsis-like illness (receiver operator characteristic area 0.75, p < 0.001) and 2) added significantly to the demographic information of birth weight, gestational age, and days of postnatal age in predicting sepsis and sepsis-like illness (p < 0.001). Continuous HRC monitoring is a generally valid and potentially useful noninvasive tool in the early diagnosis of neonatal sepsis and sepsis-like illness.