[Survival of rats subjected to different levels of pulmonary injury].

OBJECTIVE To determine a pulmonary injury model in rats that is associated with moderate mortality after extubation. DESIGN AND SETTING An experimental study in an animal model of ventilator-induced lung injury in the animal research laboratory in Virgen de las Nieves University Hospital. SUBJECTS AND METHOD A total of 45 male Wistar-Kyoto rats weighing 250-300g received food and water ad libitum. The rats were anesthetized and a tracheotomy was performed by insertion of endotracheal tube by tracheotomy. INTERVENTIONS Pulmonary injury due to mechanical ventilation was maintained for 60 min with high tidal volume (25 ml/kg) combined with intratracheal instillation of different doses of 0,9% saline solution. Rats were randomly distributed into 3 groups (15 animals in each group) with different amounts of instilled saline solution: group I, 0.5 ml/250 g body weight; group II, 1 ml/250 g body weight, and group III, 1.5 ml/250 g body weight. MAIN MEASUREMENTS Survival of animals after extubation was recorded every 5 min for the first 40 min and then at 3 h, 24 h, 72 h, and 7 days. RESULTS Survival in rats that received 0.5, 1 and 1.5 ml/250 g of intratracheal saline solution was 60%, 43% and 0% respectively, with statistically significant differences between groups receiving 0.5 and 1.5 ml/250 g (p = 0.003). CONCLUSIONS Survival in rats mechanically ventilated with high moderate volume is influenced by increased doses of intratracheal saline solution and this is important to design studies that analyze the effect the interventions on mortality.