Acute pulmonary injury in a model of ruptured abdominal aortic aneurysm

The purpose of this study was to determine whether the combined insults of hemorrhagic shock and aortic clamping simulating ruptured abdominal aortic aneurysm repair had a synergistic effect on the production of pulmonary injury, indicating remote organ injury.

Animals were randomized to one of three groups, infrarenal clamp plus 1 hour of shock, infrarenal clamp plus 2 hours of shock, and supramesenteric clamp plus 1 hour of shock. Each of these groups had four subgroups; sham, shock (mean arterial pressure of 50 mm Hg), clamp, or combined [shock plus clamp]). All animals had a laparotomy with aortic clamping in only the clamp and combined groups. Five hours after clamp removal lung permeability index and neutrophil sequestration were quantified.

Lung permeability index (6.60 +/- 0.63, p < 0.05 vs all other groups) and neutrophil sequestration (3.72 +/- 0.45 vs sham and clamp, p < 0.05) were significantly increased when shock and supramesenteric clamp were combined. After 1 or 2 hours of shock and infrarenal clamping, no increase in lung permeability index was noted, although neutrophil sequestration was increased in the 2-hour shock group.

These results demonstrate the additive effect of shock and supramesenteric clamping, which initiated a cascade of injurious events that resulted in a rapid pulmonary injury. The high mortality rate related to remote organ failure in ruptured abdominal aortic aneurysm may be related to the synergy of these two injurious processes.