Pediatric research
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Intrapulmonary distribution of a peptide-phospholipid (KL4) surfactant administered through an adapter permitting maintenance of positive end-expiratory pressure was compared with distribution by instillation with disconnection from mechanical ventilation in 10 surfactant-deficient Macaca mullata preterm infants. Animals received KL4 surfactant (200 mg/kg) when the arterial to alveolar (oxygen ratio) (a/Ao2) was < or = 0.22 (approximately 50 min after birth) on mechanical ventilation. Six rhesus infants received bolus instillation of two half doses of KL4 surfactant through an endotracheal tube adapter over 10-15 s while maintaining positive end-expiratory pressure (0.4 kPa) accompanied by turning to the right and left lateral positions for 60 s. ⋯ Intrapulmonary distribution of KL4 surfactant was determined using dye-labeled microspheres or [3H]dipalmitoylphosphatidylcholine-labeled surfactant, measured by colorimetry or by scintillation counting. Lungs of each monkey were processed into 50 +/- 5 pieces to determine distribution of radiolabel or microspheres and for scanning electron microscopy. The drop in oxygen saturation was greater among monkey infants disconnected from the ventilator for surfactant instillation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Newborns are prone to severe infections and sepsis. Cytokines such as tumor necrosis factor-alpha and IL-1 beta play a major role in the initiation of the host response to infections. IL-1 receptor antagonist (IL-1ra) is a naturally occurring antagonist of IL-1 beta. ⋯ Interestingly, the mean Il-1RA plasma concentration is a factor 50-100 higher than the IL-1 beta plasma concentrations. We conclude that IL-1ra in newborns is produced in an amount equal to that in adults. An inadequate IL-1ra response does not seem to contribute to the increased morbidity and mortality of neonatal sepsis.
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Comparative Study
Mesenteric blood flow velocity and its relation to circulatory adaptation during the first week of life in healthy term infants.
We investigated early postnatal changes of the mesenteric circulation and its relationship to the systemic circulation in two groups of newborn infants. Group I (n = 10) was studied before the first feeding at 1 h and preprandially at 6 and 24 h. Group II (n = 10) was studied before the first feeding at 2 h of age and preprandially and postprandially at d 3, 4, and 5. ⋯ Middle cerebral artery Vmean increased from h 2 to d 3 with a further increase on d 4 (p < 0.01). This increase was associated with an increase in blood pressure. The relative fraction of CO to middle cerebral artery increased during the first days of life, suggesting a redistribution of blood flow to the metabolically active organs in the neonatal period.
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Adult respiratory distress syndrome (ARDS) is a critical medical problem in which severe arterial hypoxemia is often poorly responsive to conventional modes of mechanical ventilation. We studied the efficiency of mechanical ventilation of the peritoneal cavity in rabbits with experimental ARDS caused by lung lavage. The study shows that peritoneal ventilation is significantly effective in oxygenation of hypoxemic animals with ARDS and is also effective for carbon dioxide elimination. Peritoneal ventilation may be considered as an investigational method for extrapulmonary oxygenation in severe intractable hypoxemia caused by ARDS.
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Elastic unloading [otherwise known as negative ventilator compliance (Cv) or proportional assist ventilation] is a new mode of assisted mechanical ventilation. The ventilator continuously measures the volume of spontaneous breathing (V) and adjusts the pressure at the airway opening in proportion to V. The quotient of pressure above the baseline end-expiratory level per unit of V (the gain of the assist) is constant at any point in time and can be preset. ⋯ An elevation of Ctot decreased the expiratory airflow. Tidal volume increased slightly in healthy lungs and arterial PCO2 decreased. We conclude that the effects of Cv on the total compliance of the combined lung-respirator system can accurately be predicted.