Functional deficiency of pulmonary surtactant in the newborn infant

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Pulmonary surfactant dificiency is represented by respiratory distress syndrome of the newborn infant. The similar pathophysiology should be observed where the pulmonary surfactant is inactivated by certain inhibitors. We therefore performed both animal and clinical experiments in order to clarify the pathophysilogy of functional deficiency of pulmonary surfactant and affempted to estalish the straategy for the treatment.We first demonstrated the strong inhibitory activity of meconium on pulmonary surfactant, and succeeded in the kproduction of rabbit model of meconium aspiration syndrome. Trials of bronchoalveolar lavage with surfactant solution revealed that the bronchoalveolar lavage with surfactant solution followed by the surfactant repacement showed the best results in the removal of meconium from the airway as well as in pulmonary funciton. Clinical trials on the sick newborn infants showed the definitely promising results in the establishment of therapeutic procedure of meconiu … More m aspiration syndrome.Then we searched for the procedure to detect functional deficiency of pulmonary surfactant. The stable microbubble rating, most widely used for the deteciton of surfactant deficiency in the neonate, was tested for functional deficiency with the addition of the serum to the sample of tracheobrochial aspirate. The miumum surface tension measured by the pulsating bubble surfactometer could detect the inhibitory activity of the serum proteins, but the stable microbubble rating was unable even when the definite amounts of inhibitor were added.On the contrary, studies with tracheobronchial aspirates from the patients with hemorrhagic lung edema, another representative condition suspected as functional deficiency of pulmonary surfactant, revealed that the ratios of disaturated phophatidvlcholine (DSPC) to albumin and of surfactant associated protein A (SP-A) to albumin were reversely correlated to the inhibitory activity estimated by the minimum surface tension of the sample added with 1mg of artificial surfactant (S-TA) Clinical oservation also showed that the ratio of pre-and post- surfactant replacement ventilatory index indicates the inhibitory activity because the ratio wellcorrelates with the minumum surface tension of tracheobronchial aspirate samples added with the same volume of standard surfactant solution. Less