Many authors have published data stating how common abdominal compartment syndrome is in their clinical practice. Reported incidence ranges from a few percent to over 40 percent. However, as of 2004, only one article has systematically measured intra-abdominal pressure in every single patient in multiple ICU’s to determine the prevalence of intra-abdominal hypertension and abdominal compartment syndrome in a broad sample of patients.(Malbrain, Chiumello et al. 2004) (See abstract of article at end of this discussion).

The study was conducted in 13 separate ICU’s in 6 different countries. The investigators measured intra-abdominal pressure (IAP) in every patient in the ICU for a 24 hour period to determine how many had elevations of their pressures (intra-abdominal hypertension - IAH) and how many developed abdominal compartment syndrome (ACS). They defined IAH as a pressure over 12 mm Hg, severe elevation as and IAP over 15 mm Hg and ACS as a pressure over 20 mm Hg with evidence of at least one organ failure. The results are impressive for the frequency of this disease process: Over half the patients had intra-abdominal hypertension, one-third has severe IAH and almost 1 in 10 had abdominal compartment syndrome -- a disease process that dramatically increases organ failure and death. Interestingly, the medical ICU patients had as much or more ACS as the surgical/trauma patients.

Cut-off (mm Hg)	Total prevalence	MICU prevalence	SICU prevalence
IAP >= 12 mm Hg	58.8%	54.4%	65%
IAP >= 15 mm Hg	28.9%	29.8%	27.5%
IAP >= 20 mm Hg Plus organ failure	8.2%	10.5%	5%

The authors also tried to identify patients who were at risk versus those who were not -- obesity and total intravenous fluid infusion increased the risk of ACS, but no group of clinical information could separate those patients with elevated IAP from those with normal IAP. They conclude: Bladder pressure measurement is accurate for screening for elevated IAP, IAP measurements should be taken as often as is reasonably possible to detect elevated IAP early, and

"Our study suggests that there is no specific type of patient or disease or treatment that reliably indicates when IAP needs to be measured, or when measurement is not necessary in a mixed ICU population. Indeed, it seems that ..IAP should be routinely measured."

1. There has been a focus in the past on this disease as a traumatic disease. This article clearly demonstrates the IAH and ACS are present in medical as well as surgical and trauma ICU’s. In fact, it is as common or more common in the medical population. The clear point here – all ICU’s need to measure IAP.
2. Prevalence: This is the only study to define how common this disease process is in a multi-center, mixed ICU population. The high prevalence of this disease in a broad ICU population makes its detection and monitoring all the more important.
3. Prediction parameters: The ability to determine in advance who would develop IAH or ACS was very limited, making the importance of monitoring all critical patients more important.

Efstathiou, E., M. Zaka, et al. (2005). "Intra-abdominal pressure monitoring in septic patients." Intensive Care Medicine 31, Supplement 1(131): S183, Abstract 703.

INTRODUCTION. Intra-abdominal pressure measurement through the urinary bladder in critically ill patients is easily obtained by low cost means. Recent studies revealed the possible significance of this parameter variation in critically ill. Special attention was paid until now in cases of abdominal compartment syndrome (IAP > 20 mm Hg). Intra-abdominal hypertension is recognized when the elevation of the parameter exceeds 12 mm Hg.

METHODS. In a prospective study, in our mixed ICU we monitored on six hour basis for 3 days intra-abdominal pressure in 26 patients with sepsis (confirmed by elevated Procalcitonin values) with a device standardized by our team through the urinary bladder. The mean age of the patients was 64±5 years. 16 of them were medical and 10 surgical admissions.

RESULTS. Intra-abdominal hypertension is recognized in the majority of the cases we included in the study. Specific procedures like neuromuscular blockade, decompression of the gastro-intestinal tract (Levin / rectal tube, enemas) and dialysis seem to lower intra-abdominal pressure. On the contrary, massive fluid resuscitation (more than 5 liters) results in elevation of the parameter.

Cut-off (mm Hg)	Total	MICU	SICU
> 12	52.1%	67%	58%
> 15	27.6%	25.2%	29%
>20 Plus organ failure	9.3%	4.1%	6%

CONCLUSION. No specific relation is revealed between sepsis and the fluctuation of the intra-abdominal pressure but continuous IAP monitoring might prove to be a significant index of fluid resuscitation in septic patients.

Ejike, J. C. and M. Mathur (2005). "Occurence and outcome of abdominal compartment syndrome in critically ill children." Critical Care Medicine 33(12 supplement): A95, Abstract 158-M.

INTRODUCTION: Abdominal compartment syndrome (ACS) is a potential problem in critically ill children. The occurrence in adults ranges form 1- 8% with mortality as high as 61%.

HYPOTHESIS: ACS is a significant problem in critically ill children with an occurrence similar to critically ill adult patients.

METHOD: A prospective, observational study done in a tertiary PICU to determine the occurrence of ACS in critically ill children. Intra-abdominal pressures (IAP) were recorded in 6 patients clinically suspected of ACS and 45 mechanically ventilated pediatric patients if parental consent was given. Patients were enrolled within 24 hours of PICU admission and monitored every 6 hrs for 24 hrs. The intra-vesical technique was employed using optimal bladder volumes determined for each patient or 1cc/kg (up to 25cc) of 0.9%NaCl. Intra-abdominal hypertension (IAH) was defined as IAP sustained at > 12mmHg and ACS was defined as (IAP) >12 mm Hg accompanied by at least 2 acute organ system dysfunction or decompensation. Data was presented as median (range) and analyzed by Mann-Whitney U test. Significance was accepted as p <0.05.

RESULTS: Of 146 mechanically ventilated patients admitted, 51 (34.9%) were studied. Ten of 45 (22.2%) not clinically suspect for ACS had IAH of which 3 developed ACS. The 6 clinically suspected of having ACS had ACS. Therefore 9/51 (17.6%) mechanically ventilated PICU patients had ACS. The median IAP with ACS was 18mmHg (13-32mmHg). The mortality associated with ACS was significant, 3/9 (33.3%) ACS vs 1/41 (2.4%) non-ACS; (p=0.01). Of the 6 ACS patients who survived, 1 had decompressive laparotomy with open abdomen management and 1 had abdominal decompression by peritoneal drain placement for ascitis. The median length of PICU stay for patients with ACS was 13d (5-35d) compared to 6d (1-72d) (p=0.06) of non-ACS patients.

CONCLUSION: The occurrence of ACS in a subset (mechanically ventilated) of patients admitted to the PICU is higher than the occurrence in adults. It is associated with a long PICU stay and significantly higher mortality compared to non-ACS patients.

INTRODUCTION. Intra-abdominal hypertension (IAH) may contribute to splanchnic hypoperfusion and multiple organ failure in critically ill patients. Nevertheless, limited information exists about IAH in septic shock patients, where severe distributive and microcirculatory abnormalities are present. Even moderate increases in intra-abdominal pressure may worsen hypoperfusion during septic shock. Our aim was to evaluate in septic shock patients compared to postoperative control patients with known risk factors for IAH: (a) the incidence and time course of IAH during early ICU stay; and (b) the consequences of IAH in lactate levels, maximum SOFA and norepinephrine requirements.

METHODS. 27 septic shock patients and 19 abdominal surgery patients with > 2 risk factors for IAH admitted consecutively were included. Intra-abdominal pressure was measured every 6 h during the first 48 h. IAH was diagnosed with 2 consecutive measurements > 20 mm Hg. Clinical data and risk factors for IAH were registered. During follow-up SOFA, peak norepinephrine doses and lactate levels were registered daily. IAH incidence was established in both groups. Lactate levels, norepinephrine requirements and SOFA scores in patients with and without IAH in both groups were statistically compared.

RESULTS. 51% of septic shock and 31% of control patients developed IAH. Septic shock patients with and without IAH were comparable in peak norepinephrine dose, SOFA and mortality. However, peak lactate levels were significantly higher in septic shock patients with IAH compared with those without IAH (3.5 vs. 1.9 mmol/L, p<0.04). There was a significant positive temporal correlation between intra-abdominal pressure and lactate in septic shock patients with IAH. Peak levels of both occurred early and decreased progressively over time. Control patients with and without IAH exhibited comparable normal lactate levels.

CONCLUSION. We demonstrated a very high incidence of IAH in septic shock. Lactate levels were significantly higher in septic shock patients with IAH compared to those patients without IAH or to control patients with IAH. There was a close temporal correlation between lactate and intra-abdominal pressure values over time.

OBJECTIVE. Although intra-abdominal hypertension (IAH) can cause dysfunction of several organs and raise mortality, little information is available on the incidence and risk factors for IAH in critically ill patients. This study assessed the prevalence of IAH and its risk factors in a mixed population of intensive care patients.

DESIGN. A multicentre, prospective 1-day point-prevalence epidemiological study conducted in 13 ICUs of six countries.

INTERVENTIONS. None.

PATIENTS. Ninety-seven patients admitted for more than 24 h to one of the ICUs during the 1-day study period.

METHODS. Intra-abdominal pressure (IAP) was measured four times (every 6 h) by the bladder pressure method. Data included the demographics, medical or surgical type of admission, SOFA score, etiological factors such as abdominal surgery, haemoperitoneum, abdominal infection, massive fluid resuscitation, and ileus and predisposing conditions such as hypothermia, acidosis, polytransfusion, coagulopathy, sepsis, liver dysfunction, pneumonia and bacteraemia.

RESULTS. We enrolled 97 patients, mean age 64+/-15 years, 57 (59%) medical and 40 (41%) surgical admission, SOFA score of 6.5+/-4.0. Mean IAP was 9.8+/-4.7 mmHg. The prevalence of IAH (defined as IAP 12 mmHg or more) was 50.5 and 8.2% had abdominal compartment syndrome (defined as IAP 20 mmHg or more). The only risk factor significantly associated with IAH was the body mass index, while massive fluid resuscitation, renal and coagulation impairment were at limit of significance.

CONCLUSION. Although we found a quite high prevalence of IAH, no risk factors were reliably associated with IAH; consequently, to get valid information about IAH, IAP needs to be measured.