Comparison of lung injuries induced by drowning with equal volume of seawater and freshwater in rabbits / 第二军医大学学报

ABSTRACT

Objective: To compare the lung injuries caused by drowning with equal volume of seawater and freshwater in rabbits. Methods: Twenty-four healthy New Zealand rabbits were randomly allocated to three groups (n = 8) control group(CG), seawater-drowning group (infused with seawater, 2 ml/kg) and freshwater-drowning group (infused with freshwater, 2 ml/kg). All rabbits were observed for 3 hours for breathing frequency, heart rate, mean arterial pressure (MAP), blood gas analysis and levels of TNF-α and IL-6. Pulmonary histopathology, ratio of wet/dry lung weight and permeation index of pulmonary capillary were recorded after the animals were sacrificed at the end of the experiment. Results: After infusion of seawater or freshwater, the respiration rates, serum levels of TNF-α and IL-6 were significantly increased (P<0.01), and the MAP was decreased (P<0.01), leading to hypoxemia and hypocapnia. Lung injuries were noticed in both seawater-drowning group and freshwater-drowning groups, with those in the former more persistent. The wet/dry ratio and permeation index of lung capillary were significantly increased after infusion in the seawater group compared with those in the other two groups (P<0.05). The cell number in the bronchoalveolar lavage fluid was significantly larger in the seawater-drowning group compared with that in the control group (P<0.01), and the lung injury was more severe than that in the freshwater group. Conclusion: Seawater infusion can lead to more serious and persistent lung injury in rabbits compared with equal volume of freshwater.