What is the role of bladder pressure assessment in the evaluation of abdominal compartment syndrome?

Updated: Jan 16, 2020
  • Author: Pamela I Ellsworth, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

Abdominal compartment syndrome (ACS) is defined as a sustained IAP (steady-state pressure concealed within the abdominal cavity) of more than 20 mm Hg (with or without an APP < 60 mm Hg) that is associated with new organ dysfunction/failure. Primary ACS refers to ACS associated with injury or disease in the abdominopelvic region that frequently requires early surgical or interventional radiological intervention. Secondary ACS refers to ACS that does not originate from the abdominopelvic region. Recurrent ACS is defined as ACS that redevelops following previous surgical or medical treatment of primary or secondary ACS. [31]

Intra-abdominal hypertension (IAH) is defined as a sustained or repeated pathological elevation in IAP (≥12 mm Hg).

In patients at risk for developing ACS, the clinical examination is unreliable for determining the presence or absence of an elevated IAP. [4, 23] Bladder pressure monitoring, therefore, is used as a surrogate for IAP monitoring. IAP must be measured with an objective, reliable, reproducible method that can be performed at intervals frequent enough to detect increases in IAP, allowing interventions to occur prior to ACS onset. [22]

Critically ill patients can develop a capillary “leak” (permeability) that results in intravascular fluid extravasation into extravascular tissue. This typically occurs during the initial 12-36 hours of critical illness when fluid resuscitation is ongoing.

One of the primary sites of fluid accumulation is within intra-abdominal tissue, which includes the bowel wall and mesentery. As the extravascular fluid accumulates in the abdominal cavity, the abdomen accommodates by expanding. However, once the abdominal wall compliance threshold is reached, further fluid accumulation results in increases in IAP. Sustained IAPs of 12 mm Hg or more significantly affect the cardiovascular, pulmonary, gastrointestinal, renal, and nervous systems and is referred to as IAH. When the IAP increases beyond 20 mm Hg and organ failure begins to develop, the patient has advanced to ACS and requires immediate surgical intervention. [32]

Currently, the most reliable method for monitoring IAP is via pressure transduction through a catheter within the peritoneal cavity. Less-invasive options include pressure transduction through a tube placed in the stomach, bladder, or rectum, [4, 23] Obeid et al found bladder pressure to be the most technically reliable and to most closely reflect pressure within the intraperitoneal cavity. [33] Bladder pressures obtained through a Foley catheter correlates strongly with the IAP and is currently considered the criterion standard method of monitoring IAP by the International Consensus Committee – The World Society of Abdominal Compartment Syndrome. [31]


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