Objective: As bolus instillation of surfactant can lead to acute pulmonary, hemodynamic and cerebral side effects, we tested whether pulmonary mechanics and gas exchange differ between slow surfactant infusion and bolus administration.
Design and setting: Prospective, randomized pilot study in a tertiary care university hospital.
Patients and methods: Of 20 consecutive preterm infants (27-35 weeks' gestation) with severe respiratory distress syndrome) who were enrolled 14 with bovine surfactant finally were analyzed.
Interventions: Six treatments were administered by slow endotracheal surfactant infusion and eight as a bolus. Static compliance (C(stat)) and resistance (R(rs)) were measured every 3 min.
Results: C(stat) first decreased and then increased in both groups. In the infusion group C(stat) after 90 min was significantly higher than after bolus treatment but not after 15 or 45 min. R(rs) increased about threefold, with large fluctuations in the bolus group. After 90 min PaO(2)/FIO(2) had increased from 111+/-44 to 254+/-69 in the bolus group and from 86+/-40 to 238+/-102 in the infusion group, but early FIO(2) reduction and increase in PaO(2)/FIO(2) seemed delayed in the infusion group.
Conclusions: Very slow infusion of natural surfactant is at least as effective as bolus instillation in terms of improvement in C(stat) and oxygenation after 90 min. However, until 90 min the course of C(stat) and indices of gas exchange seem superior after bolus therapy. Because R(rs) is substantially increased, long expiratory times are required to yield complete exhalation.