Abdominal compartment syndrome
Abdominal compartment syndrome occurs when the abdomen becomes subject to increased pressure reaching past the point of intra-abdominal hypertension. ACS is present when intra-abdominal pressure rises and is sustained at > 20 mmHg and there is new organ dysfunction or failure. ACS is classified into three groups: Primary, secondary and recurrent ACS. It is not a disease and as such it occurs in conjunction with many disease processes, either due to the primary illness or in association with treatment interventions. Specific cause of abdominal compartment syndrome is not known, although some causes can be sepsis and severe abdominal trauma. Increasing pressure reduces blood flow to abdominal organs and impairs pulmonary, cardiovascular, renal, and gastro-intestinal function, causing multiple organ dysfunction syndrome and death.
Pathophysiology
Abdominal compartment syndrome occurs when tissue fluid within the peritoneal and retroperitoneal space accumulates in such large volumes that the abdominal wall compliance threshold is crossed and the abdomen can no longer stretch. Once the abdominal wall can no longer expand, any further fluid leaking into the tissue results in fairly rapid rises in the pressure within the closed space. Initially this increase in pressure does not cause organ failure but does prevent organs from working properly – this is called intra-abdominal hypertension and is defined as a pressure over 12 mm Hg in adults. ACS is defined by a sustained IAP above 20 mm Hg with new-onset or progressive organ failure. Severe organ dysfunctionent syndrome. These pressure measurements are relative. Small children get into trouble and develop compartment syndromes at much lower pressures while young previously healthy athletic individuals may tolerate an abdominal pressure of 20 mm Hg very well.The underlying cause of the disease process is capillary permeability caused by the systemic inflammatory response syndrome that occurs in every critically ill patient. SIRS leads to leakage of fluid out of the capillary beds into the interstitial space in the entire body with a profound amount of this fluid leaking into the gut wall, mesentery and retroperitoneal tissue.
- Peritoneal tissue edema secondary to diffuse peritonitis, abdominal trauma
- Fluid therapy due to massive volume resuscitation
- Retroperitoneal hematoma secondary to trauma and aortic rupture
- Peritoneal trauma secondary to emergency abdominal operations
- Reperfusion injury following bowel ischemia due to any cause
- Retroperitoneal and mesenteric inflammatory edema secondary to acute pancreatitis
- Ileus and bowel obstruction
- Intra-abdominal masses of any cause
- Abdominal packing for control of bleeding
- Closure of the abdomen under undue tension
- Ascites
- Acute pancreatitis with abscesses formation
Diagnosis
Abdominal compartment syndrome is defined as an intra-abdominal pressure above 20 mmHg with evidence of organ failure. Abdominal compartment syndrome develops when the intra-abdominal pressure rapidly reaches certain pathological values, within several hours, and lasts for 6 or more hours. The key to recognizing abdominal compartment syndrome is the demonstration of elevated intra-abdominal pressure which is performed most often via the urinary bladder, and it is considered to be the "gold standard". Multiorgan failure includes damage to the cardiac, pulmonary, renal, neurological, gastrointestinal, abdominal wall, and ophthalmic systems. The gut is the most sensitive to intra-abdominal hypertension, and it develops evidence of end-organ damage before alterations are observed in other systems. In a recent systematic review, Holodinsky et al. described 25 risk factors associated with IAH and 16 with ACS. These can be roughly categorized in three categories, which may be more helpful at the bedside to identify patients at risk. Especially noteworthy is the potential role of fluid resuscitation in the development of IAH and ACS. Recognizing the pivotal role of fluid resuscitation in the pathogenesis of IAH and ACS supplies the clinician with a target for preventive measures. Large volume resuscitation with crystalloids should be avoided in patients with or at risk of ACS.| Abdominal catastrophes | Severe organ dysfunction | Fluid balance |
| Trauma, peritonitis, acute pancreatitis, ruptured abdominal aortic aneurysm Often post-surgery | Metabolic respiratory renal hemodynamic | >3000–4000 mL in 24 h window |