Proportional assist versus assist control ventilation in premature infants

During proportional assist ventilation (PAV), the applied pressure is servo-controlled based on continuous input from the infant’s breathing. In addition, elastic and resistive unloading can be employed to compensate for the abnormalities in the infant’s lung mechanics. The aim of this study was to test the hypothesis that in very prematurely born infants remaining ventilated beyond the first week, PAV compared to assist control ventilation (ACV) would be associated with superior oxygenation. A randomised crossover study was undertaken. Infants were studied for 4 hours each on PAV and ACV in random order; at the end of each 4-h period, the oxygenation index (OI) was calculated. Eight infants, median gestational age of 25 (range 24–33) weeks, were studied at a median of 19 (range 10–105) days. It had been intended to study 18 infants but as all the infants had superior oxygenation on PAV (p = 0.0039), the study was terminated after recruitment of eight infants. The median inspired oxygen concentration (p = 0.049), mean airway pressure (p = 0.012) and OI (p = 0.012) were all lower on PAV.

Conclusion: These results suggest that PAV compared to ACV is advantageous in improving oxygenation for prematurely born infants with evolving or established BPD.