Clinicopathological analysis of premature infants treated with artificial surfactant

Our aim was to obtain new information about the relationship between infant responses to surfactant replacement therapy and histopathological changes in vital organs.

To accomplish this, the autopsy findings and clinical backgrounds of 41 very low birth weight infants (gestational week 25.6 +/- 2.3; birth weight 806.4 +/- 251.6g) who had died after receiving surfactant replacement therapy were reviewed, and those who responded to therapy were compared with those who did not. Responders were infants in whom the required FiO(2) declined by > 20% or mean airway pressure declined by > 20% within six hours of instilling surfactant (n=18); non-responders were infants who did not meet those criteria (n=23).

Gestational age, birth weight and time at treatment were similar in responders and non-responders, but survival was significantly longer in responders. The incidences of hyaline membrane disease, pulmonary interstitial emphysema, hemorrhagic necrosis and parenchymal degeneration of the liver and kidney were all higher in non-responders, whereas the incidences of bronchopulmonary dysplasia and pneumonia were higher in responders. Prior to treatment, acidosis and hypothermia were significantly more severe in non-responders, and perinatal complications, such as fetal distress and intrauterine infection, were observed more often in non-responders. Substantial degradation of vital organs had already occurred during the early post-natal or intrauterine life of the non-responders, which would be expected to interfere with the clinical response to instilled surfactant.

It is anticipated that in the future improved monitoring of immature fetuses will be indispensable to improve intrauterine fetal management and to achieve better control over the timing and mode of delivery.