Assist control volume guarantee ventilation during surfactant administration

Wheeler, K I; Davis, P G; Kamlin, C O F; Morley, C J

doi:10.1136/adc.2008.149583

Assist control volume guarantee ventilation during surfactant administration

¹
Neonatal Services, The Royal Women’s Hospital (RWH), Melbourne, Australia
²
Department of Physiology, Monash University, Melbourne, Australia
³
Murdoch Children’s Research Institute, The Royal Children’s Hospital, Melbourne, Australia
⁴
Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia

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}thewomens.org.au

Accepted 23 January 2009
Published Online First 4 February 2009

Abstract

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 (P_max) limited the delivered PIP such that most babies received tidal volumes less than the target value (V_Ttarget) immediately following surfactant delivery. Four infants, in a subgroup of 11 infants where P_max was set to less than 10 cm H₂O above baseline PIP, were still receiving <90% of V_Ttarget 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 P_max setting may restrict tidal volume delivery.

Footnotes

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.