The basic pathological process of abdominal compartment syndrome (ACS) is an increase in capillary permeability caused by systemic inflammatory response syndrome (SIRS) in critically ill patients.SIRS causes fluid to leak from the capillary bed into the systemic interstitial space, with a large amount of fluid leaking into the intestinal wall, mesenteric and retroperitoneal tissues and accumulating in large amounts, exceeding the threshold of abdominal wall compliance, so that the abdomen is no longer extensible and intra-abdominal pressure ( IAP) increases progressively.
When the intra-abdominal pressure is <12 mmHg, the patient usually does not develop; when the intra-abdominal pressure is >20 mmHg, the patient usually develops abdominal septal compartment syndrome; when the intra-abdominal pressure is between 12 and 20 mmHg, the development of abdominal septal compartment syndrome will depend on other factors.
ACS is defined as a sustained IAP of more than 20 mmHg with new or progressive organ failure. Pressure measurements are relative and ACS can occur in children with low pressures, while healthy young athletes with intra-abdominal pressures above 20 mmHg tolerate it well.
The process of damage in ACS is similar to that of septal syndrome in the extremities. As the pressure in a hollow space gradually increases, the organs begin to collapse under pressure and as the pressure increases to a point where the abdomen can no longer expand, it begins to affect the cardiovascular and pulmonary systems. When ACS reaches this level, without surgical decompression, the patient is at risk of death.