Abdominal Compartment Syndrome : Diagnostic and Prognostic Value of CT Findings - a Prospective Study

Abdominal Compartment Syndrome (ACS) is a well known condition occuring in critically ill patients in intensive care units.

This syndrome features a sustained intra abdominal hypertension (IAH) above 20 mmHg and a multiple organ failure due to the raise of the intra abdominal pressure.

Several reviews described CT findings linked to these conditions, but most of them suffer an insufficient statistical method.

Furthermore, the main CT feature described as specific in ACS, Round Belly Sign (RBS), has been highly debated since.

This study is aimed to evaluate, in a prospective way, the diagnostic and prognostic value of CT findings in abdominal hypertension and abdominal compartment syndrome patients hosted in intensive care units, based on previous reviews and adding three new CT features described for the first time.

Abdominal compartment syndrome (ACS) is a well known condition, occurring in patients hosted in intensive care units and suffering from acute abdominal disease (such as severe acute pancreatitis, trauma, hemoperitoneum, surgery, infectious disease), large volume fluid resuscitation (over 2,5L), and systemic disease such as severe sepsis or major burns.

This syndrome features a sustained intra abdominal hypertension (IAH) above 20 mmHg, measured indirectly by intra-vesical pressure, and a multiple organ failure due to the raise of the intra abdominal pressure.

IAH, which is defined as an abdominal pressure rise above 12 mmHg, does not systematically lead to ACS, and is often successfully cured with medical therapy.

When medial management fails, or ACS is present, surgical management is appropriate and consists in a decompressive laparotomy.

CT examination is not ordered for ACS diagnostic, but radiologists should be aware of this condition and CT findings in patients with IAH, as these critically ill patients are likely to have multiple CT examinations in a diagnostic purpose for the initial condition, its complications or its surveillance.

Several radiological studies have determined CT findings of IAH and ACS. Most of them failed to establish a specific and sensitive semiology of IAH, due to weak methodology (except Al-Bahrani and al.). The diagnostic significance of the "Round Belly Sign" (RBS), first described by Pickhardt and al., has been debated since. None of these studies evaluated the prognostic value of IAH CT findings.

Some of IAH CT findings may have a prognostic value, and being statistically linked to a raised risk of ACS overcome when found in at-risk patients population, with proven IAH.

The aim of this study is to evaluate diagnostic and prognostic value of CT findings in IAH in a prospective way, with a high statistic value.

These CT findings are the ones previously described in previous reviews (round belly sign, narrowing of abdominal veins, elevation of the diaphragm, bilateral inguinal herniation, bowel wall thickening with enhancement, direct visceral compression) and the ones studied here for the first time (increase of the peritoneal/abdominal ratio, semi-lunar line distension, concavity of the upper side of the para renal fascia).

Design:

For each included patient, when an abdominal CT is ordered, an intra-abdominal pressure measure is performed simultaneously to the CT examination. Presence or absence of IAH or ACS is noted.

Two radiologists (one junior and one senior specialized in abdominal emergencies imaging) review the CT examinations and note the presence or absence of the ten CT features studied, without knowing the intra-abdominal pressure value.

Patient follow-up:

* 5 days follow-up
* intra-abdominal pressure measurements
* Incidence of ACS from the time of inclusion to 28 days after.
* Evolution of organ failures
* Vital status at 28 days
* Medical and surgical therapy applied

Analysis:

* Diagnostic value of CT findings in IAH
* Prognostic value of CT findings in IAH, defining CT features statistically linked to ACS overcome, and mortality at 28 days

Prevalence of IAH is expected to be about 40 to 50% in patients in state of shock hosted in ICU. Among them, about 20% are expected to suffer from ACS.

Sensitivity of RBS in IAH is about 80% according to Al-Bahrani and al.. To evaluate the diagnostic value of RBS with (CI = \[0,68 - 0,88\]), 68 cases of IAH and about 140 patients included are needed.

Based on imaging habits in our center, length of this study is expected to be about 10 months.

Eligibility Criteria:
Inclusion Criteria:

* Critically ill patients requiring ICU hosting
* State of shock requiring vasopressive drugs
* State of shock requiring mechanical ventilation
* Abdominal CT examination ordered
* Intra abdominal pressure measurement

Exclusion Criteria:

* Age under 18 years
* Pregnancy
* Contraindication to urethral catheter
* Decompressive laparotomy before CT examination
* Absolute contraindication to CT enhancement agent
* Cystectomy
* Trusteeship/guardianship