A comparison of surfactant delivery with conventional mechanical ventilation and partial liquid ventilation in meconium aspiration injury

The objective of this study was to compare surfactant (SF) distribution and physiological effects after standard SF delivery during conventional mechanical ventilation (CMV) with that using partial liquid ventilation (PLV). A model of meconium aspiration syndrome (MAS) was developed using two groups of adult rats (n=14). After meconium instillation of 2.5 ml kg^-1 (20% v/w), SF/CMV: (n=7) CMV and SF/PLV: (n=7) PLV, received ¹⁴C-labeled surfactant (4 ml kg^-1) delivered intratracheally in four aliquots over 20 min in both groups. Sequential measurements of arterial blood chemistry and lung mechanics were performed in all animals. At the conclusion of experiments, lungs were inflated (30 cmH₂O), dried, sectioned and evaluated for radioactivity in disintegrations per minute (DPM). Surfactant distribution was improved (P<0.01) with PLV as compared to CMV with 48.8% of the pieces vs. 30.9% of the pieces receiving within 25% of the mean amount of surfactant, respectively. Further, regional distribution was also significantly more uniform with PLV than CMV: left vs right (P<0.01) lung and ventral vs. dorsal (P<0.01) regions. Finally, arterial PO₂ and ventilation efficiency index were significantly (P<0.01) greater post-treatment in SF/PLV than SF/CMV. These data demonstrate surfactant delivery with PLV, as compared to CMV alone, to be an improved method of delivering surfactant in MAS and suggest the possible utility of SF/PLV combination therapy for its treatment of other etiologies of neonatal respiratory distress.