Abstract 97

Background. Aspiration of meconium results in acute lung injury, characterized by pulmonary hypertension and intense inflammatory response. We studied the possible protective effects of immunoglobulins on pulmonary hemodynamics and inflammatory reaction in severe meconium aspiration syndrome.

Material. 19 newborn (10-12 days old) ventilated catheterized piglets with an intratracheal bolus (3 ml/kg) of a 65 mg/ml mixture of human meconium were studied.

Interventions. Mouse monoclonal antibodies of IgM class (anti vascular adhesion protein-1) was given in 8 piglets 30 min before meconium administration intravenously. Six piglets served as controls and received the vehicle only. A further group of piglets (n=5) received human polyclonal IgG. The hemodynamic changes were registered and blood gas samples taken serially for 6h after meconium instillation.

Results. The increase in mean pulmonary artery pressure and vascular resistance after meconium instillation was biphasic. Both IgM and IgG diminished the initial and the late phase rise in mean pulmonary artery pressure, but not in pulmonary vascular resistance. Both IgM and IgG further improved the oxygenation of the piglets, and the initial increase in the intrapulmonary shunt fraction was diminished by IgM. Systemic hemodynamic parameters did not differ between the study groups, except of a decrease in the mean arterial blood pressure caused by IgG. Further, IgM tended to decrease the lung inflammatory reaction.

Conclusions. Our results indicate that treatment of newborns with severe meconium aspiration with immunoglobulins significantly diminishes the pulmonary hypertensive response and improves the oxygenation, but the effects are not specific to the Ig class.