Background: Pulmonary inflammation and vasoconstriction are important pathogenetic factors in neonatal meconium aspiration syndrome (MAS).
Objectives: Study was performed to evaluate cardiopulmonary and inflammatory changes in adult rabbits after meconium administration.
Methods: Animals were anesthetized and ventilated with room air. Initial values of cardiopulmonary parameters were recorded and blood samples taken. Three animals were then sacrifice and used as controls. The others were administered saline (4 ml/kg, n = 4) or meconium (25 mg/ml, 4 ml/kg, n = 5) and were further ventilated with 100% oxygen. When respiratory failure developed, parameters were recorded and animals were ventilated for additional 5 hours. Rabbits were then sacrifice and lungs excised. Right lungs were dried to determine wet/dry weight ratio and left lungs were lavaged with saline. Differential leukocyte count in the blood and lavage fluid sediment, and total blood leukocyte count were evaluated.
Results: Instillation of meconium significantly decreased lung compliance, ventilation efficiency index and gas exchange, and increased right-to-left pulmonary shunts in comparison with saline group. No significant differences between groups were observed in mean blood pressure, heart rate, and central venous pressure. Meconium caused higher fluid and polymorphonuclear accumulation in the lungs, linked with decreased neutrophil and increased eosinophil counts in the blood.
Conclusions: Adult rabbits may be used for experimental testing of drugs influencing lung inflammation and vasoconstriction in MAS (Tab. 1, Fig. 4, Ref. 16).