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Assist control volume guarantee ventilation during surfactant administration
  1. K I Wheeler1,2,3,
  2. P G Davis1,3,4,
  3. C O F Kamlin1,3,
  4. C J Morley1,3
  1. 1
    Neonatal Services, The Royal Women’s Hospital (RWH), Melbourne, Australia
  2. 2
    Department of Physiology, Monash University, Melbourne, Australia
  3. 3
    Murdoch Children’s Research Institute, The Royal Children’s Hospital, Melbourne, Australia
  4. 4
    Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia
  1. Correspondence to Dr Kevin Wheeler, Neonatal Services, The Royal Women’s Hospital, Locked Bag 300, Cnr Grattan Street & Flemington Road. Parkville, VIC 3052, Australia; kevin.wheeler{at}


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.

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