To study on the sonograms and pathological basis of subacute lung injury and explore the clinical application of the sonograms of subacute lung injury in an oleic acid animal model.

The experimental animals were divided into experimental and control groups. Before establishing model, all the sonograms of the lungs were stored, and then the rabbits of control group were put to death. The oleic acid animal model of acute lung injury was made in the experimental group. The successful model was defined as at least one lung area shows varying degrees of multiple comet tail sign in chest sonogram. The sonograms of lungs were stored in successful model which were fed at the ordinary level and observed once a week without any intervention. The rabbits of experimental group were put to death at the end of the second weekend. The two groups of rabbits were dissected and the lungs were removed to make the tissue slices. The gross pathologic findings and microscopic histological changes of the two groups were observed and recorded.

In the control group, the sonograms of the lungs mainly showed A-lines; the gross pathological findings of the lungs were normal in size and shape, pinkish color, and smooth surface. The successful rate of multiple comet tail sign model in experimental group was 100%. In the subacute phase two weeks after the successful modeling, the main lung sonograms were A-lines and B-lines were present at the same time, the characteristics of comet tails were short and wide, confined to the near field, but not to the far field. The gross pathologic findings of the experimental group were as follows: the lungs were dark red with gray areas and the lungs were grayish on the edges; the microscopic pathologic findings were lung consolidation (8/12, 66.7%), pulmonary fibrosis (6/21, 50.0%) and pleural thicken (4/12, 33.3%). No pulmonary edema or pulmonary hemorrhage was found in the experimental group.

The presence of A-lines and B-lines at the same time and the short and wide comet tail sign were the main sonographic features suggesting the subacute phase of lung injury.