Yukino Itakura

Effect of surfactant lavage in a rabbit model of meconium aspiration syndrome

Meconium aspiration syndrome (MAS) is a frequent cause of respiratory distress in neonates. Recent reports have suggested that surfactant dysfunction contributes to the pathophysiology of MAS and surfactant therapy improves oxygenation of infants with MAS. We evaluated the effect of bronchial lavage with surfactant solution in a rabbit model of meconium aspiration. All animals were given 5 mL/kg of a 20% slurry of human meconium into the endotracheal tube and mechanically ventilated. The animals were then divided into saline lavage (n = 5) or surfactant lavage (n = 5). Lavage was performed an hour after meconium instillation. After the lavage the total amount of meconium recovered was measured. Blood gas was monitored during the experiment. The amount of meconium recovered by saline lavage was 14%, and by surfactant lavage was 57%. The surfactant group had a significant improvement in gas exchange, whereas the saline group had no improvement. It was concluded that the lavage with surfactant solution effectively washed out meconium and improved gas exchange in rabbit model of MAS.

Increased platelet activating factor in the tracheal aspirates from neonates with patent ductus arteriosus

We investigated platelet-activating factor (PAF) in the tracheal aspirate from 3 intubated low birth weight infants with symptomatic patent ductus arteriosus (PDA). PAF increased with the onset of symptomatic PDA and decreased to the control range soon after the ductal closure. The concentration of PAF in 26 samples taken during symptomatic PDA (median 16 pg/micrograms lipid phosphorus, range 1.4-1,200 pg/micrograms lipid phosphorus) was significantly higher than that of 31 samples from the same three patients during the periods without symptomatic PDA (median 1.9 pg/micrograms lipid phosphorus, range 0-12 pg/micrograms lipid phosphorus; P < 0.001). All 3 infants later developed chronic lung disease. These results suggest that large shunting PDA provokes PAF release to the air way of the neonate and that PAF might play a role in chronic lung disease developing after symptomatic PDA.

Effect of body position on tidal volume and minute ventilation in very low birthweight infants

Background: To progress the clinical treatment of neonates, especially in the management of respiration, we have to be able to measure their pulmonary function appropriately. Various methods have been developed, but little is known about the pulmonary function of very low birthweight infants (VLBWI) because of the difficulty in taking their measurements with existing equipment. We have developed a very low dead space pneumotachograph to measure lung function in VLBWI.

Severe infantile congenital myopathy with nemaline and cytoplasmic bodies: a case report

A Japanese boy had marked generalized hypotonia and weakness and progressive respiratory failure since birth. Left biceps brachii muscle biopsy at 47 days of age showed marked variation in muscle fiber size, and nemaline and/or cytoplasmic bodies in approximately 10% of the muscle fibers. To our knowledge, the presence of nemaline and cytoplasmic bodies in the same muscle has not been previously reported. The severity of his respiratory failure and muscle weakness were thought to be related to muscle immaturity since there were many undifferentiated type 2C fibers.

Functional pulmonary surfactant deficiency and neonatal respiratory disorders.

The pathophysiology of functional deficiency of pulmonary surfactant in the neonatal respiratory disorders represented by MAS, hemorrhagic lung edema and ARDS was discussed. The removal of inhibitor(s) is the cardinal procedure for MAS and the lavage with surfactant solution seems to be promising. In case of replacement therapy, we should consider using a different dose compared to the one used in RDS due to lung immaturity, in order to optimize results.