To establish an improved animal model of abdominal compartment syndrome by adding water in water sac successively.

Five sheep were chosen as experimental subjects. After anesthesia, 6.0 cm incisions were made along the midline with suture. One empty water sac was placed at first, and then six basic water sacs (total volume, 1200 ml) were added. The sutures were then knotted and the abdomen was closed without tension. Animal models were made by adding normal saline into the water sac through a conduit. The pressure was measured every 50 ml of normal saline were added, and these data were used to plot a curve. The modeling process was finished once the pressure reached 45-50 cmH₂O. At 72 hours after surgery, the sheep were executed and livers and kidneys were cut out, fixed in 10% formaldehyde solution, paraffin-embedded, and sectioned. The sections were stained with hematoxylin and eosin and observed under an optical microscope.

A curve of ACS animal abdominal volume-pressure was plotted. It showed that after a certain point, the abdominal pressure increased dramatically while abdominal volume increased (Y=-75.13+ 63.45X), which had a positive correlation (r²=0.9407, P=0.0001). Pathological examination of the kidney showed that the boundary between the cortex and medulla was clear. Glomeruli were concentrated in some parts. There was proliferation of mesangial cells (+ ) and matrix (+ ). Ballooning degeneration and granular degeneration were observed in some cells. There were many powder casts in some cavities, which were present as irregular globes. Besides, some protein casts and proximal convoluted tubule hemorrhage were observed. Distal convoluted tubules had hyaline degeneration. Pathological examination of the liver showed that many liver cells had ballooning degeneration and granular degeneration. There were dilation, congestion, and a large number of red stained liquid and lipofuscin deposition in blood vessels in the portal area, with a small amount of inflammatory cell infiltration.

An improved sheep model of abdominal compartment syndrome has been successfully created by adding water in water sac successively.