Clinical data from a multicenter, nonrandomized clinical trial (phase II) of
surfactant therapy in 206 neonates with severe
respiratory distress syndrome were evaluated by logistic risk models to identify factors that might affect response to
surfactant therapy as well as outcome. Based on the magnitude and duration of initial response to a single post-ventilatory dose of
Surfactant-TA, the response patterns were classified into three categories: A) immediate and sustained response, B) immediate response, relapse, and recovery, and C) poor or no response. Neonates with response A had significantly better outcome than those with response C. When the neonates with response A were combined with those with response B,
surfactant treatment was successful in 89% of the neonates, with a 90% survival rate in this series. The risk variables strongly associated with "non responders" were low pretreatment values for arterial pH (less than or equal to 7.25), blood pressure, and a 5-minute Apgar score (less than or equal to 6). All of these factors are known to be related to perinatal events including an intercurrent episode of
hypoxia during the first hours of life, and modify the course of "pure"
respiratory distress syndrome, in which the
surfactant deficiency is the primary factor. Some of these factors affecting the response to the
surfactant can be eliminated by improving
perinatal care including maternal transport, prevention of birth
asphyxia and initial stabilization of the neonates with respect to the cardiocirculatory system, and by treating with
surfactant at or soon after birth.