Objective: To investigate the individual and combined effects of PAGE and INO on oxygenation, pulmonary mechanics and hemodynamics in surfactant deficient piglets.

Methods: Eighteen 10 kg piglets were anaesthetised, intubated and mechanically ventilated(Bear Cub, Bear Medical Systems Inc,CA), and instrumented with arterial,central venous and Swan-Ganz catheters. Surfactant deficiency was induced with repeated saline lavage(30cc/kg) until the oxygen saturation remained <90% five minutes after completion of the previous lavage. Lung mechanics were measured with the Ventrak pulmonary function system. Cardiac output was measured by thermodilution method (Baxter Healthcare,CA) and pulmonary vascular resistance(PVR) calculated. Seventeen animals survived the lavage procedure and were allocated to one of 3 groups: Group I(Control), N=6 - Conventional ventilation(CV) for 2 hours; Group II, N=6 - CV+INO(40ppm) for 1 hour followed by CV+INO+PAGE for a further hour; Group III, N=5 - CV+PAGE for 1 hour followed by CV+PAGE+INO for 1 hour. Arterial pO2, oxygenation index(OI), pulmonary mechanics and hemodynamic variables were measured/calculated pre and post-lavage, and at 1 and 2 hours after group allocation. Animals were euthanised with a barbiturate overdose and the lungs removed and formalin fixed for histologic examination. A lung injury score was assigned on the basis of the degree of inflammatory change, hyaline membrane formation, and airway epithelial damage.

Results: Oxygenation increased with both PAGE and INO (see table). There were no significant differences in lung mechanics, PVR or lung injury scores between groups.

Table 1 No caption available.
Full size table

Conclusions:In this model of surfactant deficient lung disease improved oxygenation was seen with PAGE and INO. There was a trend toward greater improvement when PAGE was added to INO compared to adding INO to PAGE. These oxygenation changes were not accompanied by improvements in pulmonary mechanics, hemodynamics or lung injury scores.