INTRODUCTION: The purpose of this study was to examine the efficiency of a 
single dose of fast-acting exogenous surfactant (Curosurf) given to premature 
babies with progressive respiratory insufficiency. Curosurf was given as early 
rescue therapy during a brief intubation (INSURE method: 
INtubation-SURfactant-Extubation) during treatment with nasal Continuous 
Positive Airway Pressure (CPAP).
MATERIALS AND METHODS: Retrospective study of 115 premature infants with 
respiratory distress syndrome born and treated at Odense University Hospital 
during the years 1999 to 2004. The criterion for surfactant treatment was a 
decrease in the arterial/alveolar oxygen tension ratio (or corresponding values 
for the fraction of inspired oxygen) below 0.36 in infants with gestational age 
(GA) < 30 weeks and 0.22 in more mature infants.
RESULTS: The primary end point was survival during the first week of life 
without mechanical ventilation. This end point was reached by 51% of the infants 
with GA < 30 weeks. However, the effect proved to be GA-dependent, increasing 
from 22% in infants with a GA of 24-25 weeks to 86% in week 29. Seventy percent 
survived to be discharged. In infants with GA > 29 weeks the effect was 87%, and 
all survived.
CONCLUSION: The effect of surfactant therapy administered per the INSURE method 
is GA-dependent, and the method works best after GA week 25. The question is 
whether earlier therapy will increase its efficiency or the method has reached 
its limit.