Pediatric research
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Premature infants are at unique risk for developing acute kidney injury (AKI) due to incomplete nephrogenesis, early exposure to nephrotoxic medications, and coexisting conditions such as patent ductus arteriosus (PDA) and respiratory distress syndrome (RDS). Unfortunately, laboratory testing for the diagnosis of AKI in this population is problematic because of the physiology of both the placenta and the extra-uterine premature kidney. Recent research has led to the development of promising biomarkers for the early detection of AKI in children but there are no published reports in neonates. ⋯ Neonates born at earlier gestational ages and lower BWs had higher urine NGAL levels (p < 0.01). We conclude that urine NGAL is easily obtained in premature infants and that it correlates significantly with both BW and gestational age. The use of urinary NGAL as a biomarker of AKI in premature infants warrants further investigation.
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Hydrogen peroxide (H2O2) and nitric oxide (NO) contribute to the pathogenesis of cerebral hypoxic-ischemic injury. We evaluated the neuroprotective effect of N-acetyl-l-cysteine (NAC, a free radical scavenger) against oxidative stress and perfusion in a model of neonatal hypoxia-reoxygenation (H-R). Piglets (1-3 d, 1.6-2.3 kg) were randomized into a sham-operated group (without H-R) (n = 5) and two H-R experimental groups (2 h normocapnic alveolar hypoxia followed by 4 h reoxygenation) (n = 7/group). ⋯ Postresuscitation NAC treatment significantly attenuated the increase in cortical H2O2, but not NO, concentration during reoxygenation, with lower cerebral oxidized glutathione levels. NAC-treated piglets had significantly higher carotid oxygen delivery and lower cerebral lactate levels than that of H-R controls with corresponding changes in carotid arterial flow and vascular resistance. In newborn piglets with H-R, postresuscitation administration of NAC reduced cerebral oxidative stress and improved cerebral perfusion.
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Neonatal hyperbilirubinemia can cause bilirubin encephalopathy (kernicterus). Spontaneously jaundiced (jj) Gunn rats treated with sulfonamide (sulfa) to displace bilirubin from serum albumin, develop bilirubin encephalopathy and abnormal brainstem auditory evoked potentials (BAEPs) comparable with human newborns. We hypothesized phenylhydrazine (PHZ)-induced hemolysis would significantly elevate total plasma bilirubin (TB) in jj Gunn rat pups and produce BAEP abnormalities similar to those observed after sulfa. ⋯ BAEP wave II and III amplitudes decreased, and I-II and I-III interwave intervals increased indicating abnormal central (brainstem) auditory function. PHZ-induced hemolysis in jaundiced Gunn rat pups produces sufficiently elevated TB levels to produce bilirubin encephalopathy. This new model may be a more clinically relevant experimental model of kernicterus- and bilirubin-induced neurologic disorders.
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Apneic episodes are frequent in the preterm neonate and particularly in active sleep (AS), when functional residual capacity (FRC) can be decreased. Furthermore, FRC may be inversely correlated with the speed of blood-O(2)-desaturation. We evaluated the potential involvement of FRC in the mechanisms responsible for blood-O(2)-desaturation during short central apneic events (>3 s) in "late-preterm" infants and analyzed the specific influence of sleep state. ⋯ In AS only, there was a negative relationship between FRC and the proportion of apneas with desaturation. Even in late preterm infants who do not experience long-lasting apnea, blood-O(2)-desaturation during short apneic events is related (in AS but not QS) to a low baseline FRC. Sleep stage differences argue for a major role of AS-related mechanisms in the occurrence of these apneas.
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Endotracheal tube (ETT) suction is the most frequently performed invasive procedure in ventilated newborn infants and is associated with adverse effects related to negative tracheal pressure. We aimed to measure suction catheter gas flow and intratracheal pressure during ETT suction of a test lung and develop a mathematical model to predict tracheal pressure from catheter and ETT dimensions and applied pressure. Tracheal pressure and catheter flow were recorded during suction of ETT sizes 2.5-4.0 mm connected to a test lung with catheters 5-8 French Gauge and applied pressures of 80-200 mm Hg. ⋯ The fraction of applied pressure transmitted to the trachea was accurately modeled using ETT and catheter dimensions (R = 0.98-0.99). Negative tracheal pressure during in vitro ETT suction is directly proportional to applied pressure. This relationship is determined by ETT and catheter dimensions.