Pediatric research
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Ureaplasma respiratory tract colonization stimulates prolonged, dysregulated inflammation in the lungs of preterm infants, contributing to bronchopulmonary dysplasia (BPD) pathogenesis. Surfactant protein-A (SP-A), a lung collectin critical for bacterial clearance and regulating inflammation, is deficient in the preterm lung. To analyze the role of SP-A in modulating Ureaplasma-mediated lung inflammation, SP-A deficient (SP-A-/-) and WT mice were inoculated intratracheally with a mouse-adapted U. parvum isolate and indices of inflammation were sequentially assessed up to 28 d postinoculation. ⋯ However, nitrite generation in response to Ureaplasma infection was blunted at 24 h and Ureaplasma clearance was delayed in SP-A-/- mice compared with WT mice. Coadministration of human SP-A with the Ureaplasma inoculum to SP-A-/- mice reduced the inflammatory response, but did not improve the bacterial clearance rate. SP-A deficiency may contribute to the prolonged inflammatory response in the Ureaplasma-infected preterm lung, but other factors may contribute to the impaired Ureaplasma clearance.
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Meconium aspiration syndrome (MAS) is one of the top causes of severe respiratory failure in neonates. This study was designed to investigate the effective volume of therapeutic bronchoalveolar lavage (BAL) with diluted surfactant in the treatment of MAS in newborn piglets. Human meconium was instilled in 24 piglets to induce MAS, and the piglets were randomly divided into four groups: 1) control, no lavage; 2) lavage-10, BAL with diluted surfactant (5 mg/mL, Survanta) 10 mL/kg in two aliquots; 3) lavage-20, 20 mL/kg in two aliquots; 4) lavage-30, 30 mL/kg in two aliquots. ⋯ The changes in oxygenation and lung compliance of lavage-20 and lavage-30 groups were significantly better than control and lavage-10 groups (p < 0.05), but there was no significant difference between lavage-20 and lavage-30 groups. The lung injury scores were significantly lower in the dependent site of lavage-20 and lavage-30 groups than the other two groups. In conclusion, using 20 mL/kg diluted surfactant in two aliquots to perform therapeutic BAL was as effective as 30 mL/kg in improving the pathophysiological outcomes in MAS and may warrant consideration clinically in treating MAS.
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Neurally adjusted ventilatory assist (NAVA), a mode of mechanical ventilation controlled by diaphragmatic electrical activity (EAdi), may improve patient-ventilator interaction. We examined patient-ventilator interaction by comparing EAdi to ventilator pressure during conventional ventilation (CV) and NAVA delivered invasively and non-invasively. Seven intubated infants [birth weight 936 g (range, 676-1266 g); gestational age 26 wk (range, 25-29)] were studied before and after extubation, initially during CV and then NAVA. ⋯ Pressure delivery during conventional ventilation was not correlated to EAdi. Neural expiratory time was longer (p = 0.044), and respiratory rate was lower (p = 0.004) during NAVA. We conclude that in low birth weight infants, NAVA can improve patient-ventilator interaction, even in the presence of large leaks.
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The effect of a 20 s sustained inflation (SI) and positive end-expiratory pressure (PEEP) on functional residual capacity (FRC) formation at birth were investigated. Preterm rabbit pups (28 d) were randomized at birth into four groups (n = 6 for each): 1) SI, PEEP 5 cm H2O, 2) no SI, PEEP 5 cm H2O, 3) no SI + no PEEP, 4) SI + no PEEP. FRC and tidal volume (Vt) were measured by plethysmography and uniformity of lung aeration by phase contrast x-ray imaging. ⋯ FRC was greater with SI (p = 0.006) during the first minute, but was larger with PEEP than without PEEP throughout the first 7 min (p < 0.0005). Effects of PEEP and SI were additive. In ventilated preterm rabbits at birth, combining a SI and PEEP improved FRC formation and uniformity of lung aeration, but PEEP had the greatest influence.
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Review
Oxygen saturation monitoring for the preterm infant: the evidence basis for current practice.
Many of the morbid conditions associated with extreme immaturity are potentiated by an excess of free radicals occurring in infants who developmentally have decreased levels of antioxidants. The optimal oxygen saturation values for the resuscitation, stabilization, and ongoing care of the very low birth weight infant remain largely undefined. We have reviewed the currently available evidence for clinical oxygen use in the newborn period. ⋯ For ongoing management of preterm infants, SpO2 targets of 85-93% seem to be most appropriate, with alarm limits set within 1 to 2% of these targets with intermittent audits to ensure compliance. There is no strong evidence to support the use of altered limits for the infant who develops early evidence of retinopathy of prematurity. Further prospective studies are required to evaluate the effects of varied oxygen targets on long-term outcome.