Tracheal aspirate surface tension in babies with hyaline membrane disease: effects of synthetic surfactant replacement.

Abstract

Our objective was to determine changes in surface tension of tracheal aspirate over the first 4-5 days of life in babies with hyaline membrane disease, with and without synthetic surfactant replacement. Tracheal aspirates were collected prior to and for 96-108 hr after initiation of a randomized double-blind trial of synthetic surfactant (EXOSURF Neonatal) or air-treated control patients. Using the captive bubble technique, we measured minimum surface tension (initial adsorption, first quasi-static compression, dynamic cycling at 30 cpm, second quasi-static compression and 5 min after quasi-static compressions) in 39 surfactant-treated and 44 control babies. We also compared minimum surface tension with the respiratory support provided. Twelve hours after one dose of synthetic surfactant, minimum surface tension on first quasistatic compression decreased significantly from 20.9+/-1.4 to 17.6+/-1.3 mN/m compared to air-treated babies, who did not show any change. Reduction in minimum tracheal aspirate surface tension on first quasi-static compression and during dynamic cycling over 48-60 hr occurred more rapidly in surfactant-treated babies. Ventilator support did not correlate with minimum tracheal aspirate surface tension. We conclude that treatment of babies with synthetic surfactant improved tracheal aspirate minimum surface tension within 12 hr of the first dose and for the next 48-60 hr.