Objective     To establish an animal model of newborn meconium aspiration syndrome (MAS) by tiny volume ventilation with small animal ventilator. Methods     Twenty-five healthy newborn rats (5- ～7-day-old) were randomly assigned to MAS group and sham group (normal saline

NS)

with 10 animals in each group after model establishment

and the left 1 rat served as normal control. The rats from the MAS group were inflicted with meconium infusion via endotrachea tube

and those of the sham group were given infusion of normal saline. All rats were analyzed with blood gas analysis

lung X-ray filming

wet/dry ratio and pathological examination. Results      The pH value and partial pressure of oxygen were significantly lower in the MAS than the NS groups (7.19±0.11 vs 7.31±0.08

25±9 vs 62±12 mmHg

P0.05). X-ray filming showed that the rate of meconium aspiration was higher in the MAS than the NS groups (10/10 vs 1/10). And the wet/dry ratio was significantly higher in the MAS rats than the NS rats (5.85±0.47 vs 4.28±0.71

P0.05). The MAS rats displayed typical pathological changes of MAS

while the NS rats showed uniform lung alveolar ventilation

without obvious edema. Conclusion     It is feasible to establish MAS model under tiny volume ventilation in newborn rats. And the model  can provide a stable small animal model for neonatal lung injury.