Objective: To measure changes in ventilator parameters in preterm infants receiving surfactant during assist control volume guarantee (AC/VG) ventilation.
Methods: 22 preterm infants (up to 32 weeks’ gestation) receiving surfactant for respiratory distress syndrome were enrolled in a prospective study of ventilator parameters during AC/VG ventilation at a tertiary neonatal intensive care unit. Ventilator pressures, flow and tidal volume waveforms were recorded from the Dräger Babylog 8000 plus in real time, and compared to pre-surfactant measurements.
Results: Following surfactant administration, 21 of 22 babies experienced completely obstructed endotracheal gas flow. Peak inflation pressure (PIP) increased by a median (IQR) of 8 (4–10) cm H2O, and took 30–60 min to return to baseline. Inspired oxygen concentration was reduced from a median (IQR) of 39% (26%–44%) to 26% (21%–30%) in the first 5 min. The set maximum PIP (Pmax) limited the delivered PIP such that most babies received tidal volumes less than the target value (VTtarget) immediately following surfactant delivery. Four infants, in a subgroup of 11 infants where Pmax was set to less than 10 cm H2O above baseline PIP, were still receiving <90% of VTtarget 20 min post surfactant.
Conclusions: When giving surfactant during AC/VG ventilation, complete obstruction is common. PIPs increased and remain elevated for 30–60 min. The Pmax setting may restrict tidal volume delivery.
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Funding This research was funded by Australian National Health and Medical Research Council Program Grant no. 384100.
Competing interests None.
Ethics approval This study was approved by the RWH Research Committee.