CT-scan assessment of lung volumes and effect of gravity on lung ventilation during and after total liquid ventilation in piglets

Total liquid ventilation (TLV) offers hope for helping nano-preterm infants adapt to the extrauterine environment at birth. We aimed to test whether lung volumes could be maintained over time during TLV and whether the prone position altered the distribution of perflubron during and following TLV. CT scan images were acquired in seven newborn piglets during 180 min of TLV, followed by 120 min of weaning. End-expiratory lung volumes increased from 43.0 [38.1, 44.4] cm³/kg at baseline to 53.5 [50.6, 67.8] cm³/kg (p = 0.036) at 60 min of TLV through recruitment of the dependent (posterior) lung regions. They remained stable thereafter at 55.4 [45.0, 64.5] cm³/kg at 150 min (p = 0.5 vs. 60 min). Change to the prone position during TLV did not alter the proportion of the tidal volume distributed to the anterior lung regions (p = 0.9). However, the prone position during weaning (rotating experimental group, n = 3) favored distribution of the gaseous tidal volume to the nondependent lung regions. In conclusion, perflubron did not accumulate in the lungs after the initial recruitment of gravity-dependent regions. In addition, prone positioning did not affect tidal volume distribution during TLV but increased ventilation of the nondependent lung regions during weaning.