High Risk, Low Prevalence: Abdominal Compartment Syndrome

Abdominal compartment syndrome is a time-sensitive cause of shock, oliguria, and ventilatory failure in critically ill patients. It is defined by elevated intra-abdominal pressure with new end-organ injury, and bedside bladder pressure measurement is the diagnostic standard emergency clinicians can set up in the ED.

Recognizing Abdominal Compartment Syndrome

• Poly-compartment pressure state: ACS is not just a tense belly; it is a pressure-driven syndrome that impairs renal, respiratory, cardiovascular, gut, and even cerebral perfusion as intra-abdominal pressure rises.
• High-risk ED phenotypes: Think ACS in burns, sepsis, pancreatitis, massive fluid resuscitation, ascites, ileus, obesity, prior abdominal surgery, or any intubated patient with falling reserve.
• Early renal warning sign: Decreased urine output is one of the earliest bedside clues, often accompanied by rising creatinine as elevated abdominal pressure reduces renal blood flow.
• Bedside clinical pattern: Refractory hypotension, abdominal distension, hypoxia or hypercapnia, and high inspiratory pressure alarms should push ACS higher on the differential in the crashing patient.
• Diagnostic pressure threshold: ACS is defined as intra-abdominal pressure above 20 mm Hg plus end-organ injury; CT may suggest compression, but it does not establish the diagnosis. We get into the bedside diagnostic framing in the episode.

Diagnosis and Initial Management

• Bladder pressure gold standard: Intra-abdominal pressure measured through the Foley is the diagnostic standard, using equipment most EDs already have with an arterial line transducer setup.
• Measurement setup essentials: Accurate readings depend on a supine patient, an emptied bladder, transducer zeroed at bladder level, and measurement taken at end-exhalation. We walk through the setup details in the chapter.
• Abdominal perfusion target: Management centers on abdominal perfusion pressure, calculated as MAP minus IAP, to preserve organ blood flow while definitive treatment is arranged.
• Fluid strategy caution: Excess IV fluid can worsen ACS by increasing capillary leak and third spacing, so many patients need a net-even strategy rather than reflexive resuscitation.
• Pressure-lowering measures: Initial treatment focuses on decompression and compliance: keep the patient supine, decompress stomach or ascites, drain large effusions, and minimize PEEP when possible.
• Surgical decompression timing: Failure of medical management is an indication for operative decompression, and outcomes are worse when surgery is delayed beyond 4 days from diagnosis.

References:

1. Gottlieb M, Koyfman A, Long B. Evaluation and Management of Abdominal Compartment Syndrome in the Emergency Department. J Emerg Med. 2020;58(1):43-53. PMID: 31753758
2. Harty S. Annals of B-Pod: Abdominal Compartment Syndrome. Taming the SRU. Published June 22, 2017. Accessed August 2, 2023. https://www.tamingthesru.com/blog/annals-of-b-pod/june-2017/abdominal-compartment-syndrome?rq=bladder%20pressure