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1.  Incidence and prognosis of intra-abdominal hypertension in critically ill medical patients: a prospective epidemiological study 
Annals of Intensive Care  2012;2(Suppl 1):S3.
The aim of this study was to determine the incidence of intra-abdominal hypertension (IAH) in patients with two or more categorized risk factors (CRF) for IAH, and their morbidity and mortality during their intensive care unit (ICU) stay.
Prospective cohort study carried out at a medical ICU. A total of 151 medical patients were enrolled during a period of 3 months. After ICU whole staff training, we conducted daily screening of the four CRF for IAH based on the World Society of Abdominal Compartment Syndrome (WSACS) guidelines (namely, diminished abdominal wall compliance, increased intraluminal content, increased abdominal content, and capillary leak syndrome or fluid resuscitation). In those patients with risk factors of at least two different categories (≥2 CRF), intra-abdominal pressure (IAP) was measured every 8 h during ICU stay. Data included demographics, main diagnosis on admission, severity scores, cumulative fluid balance, daily mean IAP, resolution of IAH, days of ICU and hospital stay, and mortality.
Eighty-seven patients (57.6%) had ≥2 CRF for IAH, 59 (67.8%) out of whom developed IAH. Patients with ≥2 CRF had a significantly higher mortality rate (41.4 vs. 14.3%, p < 0.001). Patients with IAH had higher body mass index, severity scores, organ dysfunctions/failures, number of CRF for IAH, days of ICU/hospital stay and hospital mortality rate (45.8 vs. 32.1%, p = 0.22). Non-resolution of IAH was associated with a higher mortality rate (64.7 vs. 35.3%, p = 0.001). None of the cohort patients developed abdominal compartment syndrome. The multivariate analysis showed that IAH development (odds ratio (OR) 4.09; 95% confidence interval (CI) 0.83-20.12) was a non-independent risk factor for mortality, and its non-resolution (OR 13.15; 95% CI 22.13-81.92) was an independent risk factor for mortality.
Critically ill medical patients admitted to ICU with ≥2 CRF have high morbidity, mortality rate, and incidence of IAH, so IAP should be measured and monitored as recommended by the WSACS. Our study highlights the importance of implementing screening and assessment protocols for an early diagnosis of IAH.
PMCID: PMC3390290  PMID: 22873419
intra-abdominal hypertension; abdominal compartment syndrome; intra-abdominal pressure; multiple organ failure; critically ill patients; intensive care.
2.  Intra-abdominal hypertension in patients with severe acute pancreatitis 
Critical Care  2005;9(4):R452-R457.
Abdominal compartment syndrome has been described in patients with severe acute pancreatitis, but its clinical impact remains unclear. We therefore studied patient factors associated with the development of intra-abdominal hypertension (IAH), the incidence of organ failure associated with IAH, and the effect on outcome in patients with severe acute pancreatitis (SAP).
We studied all patients admitted to the intensive care unit (ICU) because of SAP in a 4 year period. The incidence of IAH (defined as intra-abdominal pressure ≥ 15 mmHg) was recorded. The occurrence of organ dysfunction during ICU stay was recorded, as was the length of stay in the ICU and outcome.
The analysis included 44 patients, and IAP measurements were obtained from 27 patients. IAH was found in 21 patients (78%). The maximum IAP in these patients averaged 27 mmHg. APACHE II and Ranson scores on admission were higher in patients who developed IAH. The incidence of organ dysfunction was high in patients with IAH: respiratory failure 95%, cardiovascular failure 91%, and renal failure 86%. Mortality in the patients with IAH was not significantly higher compared to patients without IAH (38% versus 16%, p = 0.63), but patients with IAH stayed significantly longer in the ICU and in the hospital. Four patients underwent abdominal decompression because of abdominal compartment syndrome, three of whom died in the early postoperative course.
IAH is a frequent finding in patients admitted to the ICU because of SAP, and is associated with a high occurrence rate of organ dysfunction. Mortality is high in patients with IAH, and because the direct causal relationship between IAH and organ dysfunction is not proven in patients with SAP, surgical decompression should not routinely be performed.
PMCID: PMC1269467  PMID: 16137360
3.  Abdominal compartment syndrome in patients with severe acute pancreatitis in early stage 
AIM: To study retrospectively the influence of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in patients with early acute pancreatitis (AP) (during the first week after admission) on physiological functions, and the association of the presence of IAH/ACS and outcome.
METHODS: Patients (n = 74) with AP recruited in this study were divided into two groups according to intra-abdominal pressure (IAP) determined by indirect measurement using the transvesical route via Foley bladder catheter during the first week after admission. Patients (n = 44) with IAP ≥ 12 mmHg were assigned in IAH group, and the remaining patients (n = 30) with IAP < 12 mmHg in normal IAP group. For analysis of the influence of IAH/ACS on organ function and outcome, the physiological parameters and the occurrence of organ dysfunction during intensive care unit (ICU) stay were recorded, as were the incidences of pancreatic infection and in-hospital mortality.
RESULTS: IAH within the first week after admission was found in 44 patients (59.46%). Although the APACHE II scores on admission and the Ranson scores within 48 h after hospitalization were elevated in IAH patients in early stage, they did not show the statistically significant differences from patients with normal IAP within a week after admission (16.18 ± 3.90 vs 15.70 ± 4.25, P = 0.616; 3.70 ± 0.93 vs 3.47 ± 0.94, P = 0.285, respectively). ACS in early AP was recorded in 20 patients (27.03%). During any 24-h period of the first week after admission, the recorded mean IAP correlated significantly with the Marshall score calculated at the same time interval in IAH group (r = 0.635, P < 0.001). Although ACS patients had obvious amelioration in physiological variables within 24 h after decompression, the incidences of pancreatitic infection, septic shock, multiple organ dysfunction syndrome (MODS) and death in the patients with ACS were significantly higher than that in other patients without ACS (pancreatitic infection: 60.0% vs 7.4%, P < 0.001; septic shock: 70.0% vs 11.1%, P < 0.001; MODS: 90.0% vs 31.5%, P < 0.001; mortality: 75.0% vs 3.7%, P < 0.001).
CONCLUSION: IAH/ACS is a frequent finding in patients admitted to the ICU because of AP. Patients with IAP at approximately 10-12 mmHg and early signs of changes in physiologic variables should be seriously considered for urgent decompression to improve survival.
PMCID: PMC2716618  PMID: 18567084
Acute pancreatitis; Abdominal compartment syndrome; Intra-abdominal pressure; Intra-abdominal hypertension; Organ dysfunction
4.  Current recognition and management of intra-abdominal hypertension and abdominal compartment syndrome among tertiary Chinese intensive care physicians*  
This survey was designed to clarify the current understanding and clinical management of intra-abdominal hypertension (IAH)/abdominal compartment syndrome (ACS) among intensive care physicians in tertiary Chinese hospitals. A postal twenty-question questionnaire was sent to 141 physicians in different intensive care units (ICUs). A total of 108 (76.6%) questionnaires were returned. Among these, three quarters worked in combined medical-surgical ICUs and nearly 80% had primary training in internal or emergency medicine. Average ICU beds, annual admission, ICU length of stay, acute physiology and chronic health evaluation (APACHE) II score, and mortality were 18.2 beds, 764.5 cases, 8.3 d, 19.4, and 21.1%, respectively. Of the respondents, 30.6% never measured intra-abdominal pressure (IAP). Although the vast majority of the ICUs adopted the exclusively transvesicular method, the overwhelming majority (88.0%) only measured IAP when there was a clinical suspicion of IAH/ACS and only 29.3% measured either often or routinely. Moreover, 84.0% used the wrong priming saline volume while 88.0% zeroed at reference points which were not in consistence with the standard method for IAP monitoring recommended by the World Society of Abdominal Compartment Syndrome. ACS was suspected mainly when there was a distended abdomen (92%), worsening oliguria (80%), and increased ventilatory support requirement (68%). Common causes for IAH/ACS were “third-spacing from massive volume resuscitation in different settings” (88%), “intra-abdominal bleeding”, and “liver failure with ascites” (52% for both). Though 60% respondents would recommend surgical decompression when the IAP exceeded 25 mmHg, accompanied by signs of organ dysfunction, nearly three quarters of respondents preferred diuresis and dialysis. A total of 68% of respondents would recommend paracentesis in the treatment for ACS. In conclusion, urgent systematic education is absolutely necessary for most intensive care physicians in China to help to establish clear diagnostic criteria and appropriate management for these common, but life-threatening, diseases.
PMCID: PMC3030961  PMID: 21265048
Questionnaire; Intra-abdominal pressure; Intra-abdominal hypertension; Decompression laparotomy; Abdominal compartment syndrome
5.  Recognition and management of abdominal compartment syndrome among German pediatric intensivists: results of a national survey 
Annals of Intensive Care  2012;2(Suppl 1):S8.
Several decades ago, the beneficial effects of goal-directed therapy, which include decompressive laparotomy (DL) and open abdomen procedures in cases of intra-abdominal hypertension (IAH) in children, were proven in the context of closures of abdominal wall defects and large-for-size organ transplantations. Different neonatologic and pediatric disease patterns are also known to be capable of increasing intra-abdominal pressure (IAP). Nevertheless, a considerable knowledge transfer regarding such risk factors has hardly taken place. When left undetected and untreated, IAH threatens to evolve into abdominal compartment syndrome (ACS), which is accompanied by a mortality rate of up to 60% in children. Therefore, the present study looks at the recognition and knowledge of IAH/ACS among German pediatric intensivists.
In June 2010, a questionnaire was mailed to the heads of pediatric intensive care units of 205 German pediatric hospitals.
The response rate was 62%. At least one case of IAH was reported by 36% of respondents; at least one case of ACS, by 25%. Compared with adolescents, younger critically ill children appeared to develop IAH/ACS more often. Routine measurements of IAP were said to be performed by 20% of respondents. Bladder pressure was used most frequently (96%) to assess IAP. Some respondents (17%) only measured IAP in cases of organ dysfunction and failure. In 2009, the year preceding this study, 21% of respondents claimed to have performed a DL. Surgical decompression was indicated if signs of organ dysfunction were present. This was also done in cases of at least grade III IAH (IAP > 15 mmHg) without organ impairment.
Although awareness among pediatricians appears to have been increasing over the last decade, definitions and guidelines regarding the diagnosis and management of IAH/ACS are not applied uniformly. This variability could express an ever present lack of awareness and solid prospective data.
PMCID: PMC3390295  PMID: 22873424
intra-abdominal pressure; intra-abdominal hypertension; abdominal compartment syndrome; children; intensive care unit; questionnaire; decompressive laparotomy.
6.  The role of intestinal mucosa injury induced by intra-abdominal hypertension in the development of abdominal compartment syndrome and multiple organ dysfunction syndrome 
Critical Care  2013;17(6):R283.
Abdominal distension is common in critical illness. There is a growing recognition that intra-abdominal hypertension (IAH) may complicate nonsurgical critical illness as well as after abdominal surgery. However, the pathophysiological basis of the injury to the intestinal mucosal barrier and its influence on the onset of abdominal compartment syndrome (ACS) and multiorgan dysfunction syndrome (MODS) remain unclear. We measured intestinal microcirculatory blood flow (MBF) during periods of raised intra-abdominal pressure (IAP) and examined how this influenced intestinal permeability, systemic endotoxin release, and histopathological changes.
To test different grades of IAH to the injury of intestinal mucosa, 96 New Zealand white rabbits aged 5 to 6 months were exposed to increased IAP under nitrogen pneumoperitoneum of 15 mmHg or 25 mmHg for 2, 4 or 6 hours. MBF was measured using a laser Doppler probe placed against the jejunal mucosa through a small laparotomy. Fluorescein isothiocyanate (FITC)-conjugated dextran was administered by gavage. Intestinal injury and permeability were measured using assays for serum FITC-dextran and endotoxin, respectively, after each increase in IAP. Structural injury to the intestinal mucosa at different levels of IAH was confirmed by light and transmission electron microscopy.
MBF reduced from baseline by 40% when IAP was 15 mmHg for 2 hours. This doubled to 81% when IAP was 25 mmHg for 6 hours. Each indicator of intestinal injury increased significantly, proportionately with IAP elevation and exposure time. Baseline serum FITC-dextran was 9.30 (± SD 6.00) μg/ml, rising to 46.89 (±13.43) μg/ml after 15 mmHg IAP for 4 hours (P <0.01), and 284.59 (± 45.18) μg/ml after 25 mmHg IAP for 6 hours (P <0.01). Endotoxin levels showed the same pattern. After prolonged exposure to increased IAP, microscopy showed erosion and necrosis of jejunal villi, mitochondria swelling and discontinuous intracellular tight junctions.
Intra-abdominal hypertension can significantly reduce MBF in the intestinal mucosa, increase intestinal permeability, result in endotoxemia, and lead to irreversible damage to the mitochondria and necrosis of the gut mucosa. The dysfunction of the intestinal mucosal barrier may be one of the important initial factors responsible for the onset of ACS and MODS.
PMCID: PMC4057115  PMID: 24321230
7.  The secondary abdominal compartment syndrome: not just another post-traumatic complication 
Canadian Journal of Surgery  2008;51(5):399-405.
The secondary abdominal compartment syndrome (ACS) is defined as the presence of organ dysfunction with concurrent intra-abdominal hypertension (IAH) in a scenario lacking primary intraperitoneal injury or intervention. This state appears to be related to visceral, abdominal wall and retroperitoneal edema and ascites induced by resuscitation. Despite a diverse range of associated causes such as pancreatitis, intra-abdominal sepsis, cardiac arrest, thermal injury and extraperitoneal trauma, this class of ACS is characterized by the presence of shock requiring aggressive fluid resuscitation. Secondary ACS is an extreme condition along a continuum of raised intra-abdominal pressure (IAP) that is pathoneumonic when associated with new overt organ failure. When IAP is above normal but is not associated with organ failure, IAH is diagnosed. Because these conditions are common among critically ill patients, the measurement of IAP is crucial. It is unclear whether preventing IAH reduces progression to ACS or influences outcomes. When overt ACS is confirmed, immediate surgical decompression of the patient's abdomen via a standard laparotomy is usually required. Because many disease processes resulting in critical illness require aggressive fluid resuscitation as a primary therapy, it is likely that secondary ACS is much more common than previously believed. Further study is needed.
PMCID: PMC2556543  PMID: 18841232
8.  How central obesity influences intra-abdominal pressure: a prospective, observational study in cardiothoracic surgical patients 
Intra-abdominal hypertension (IAH) is frequently present in critically ill patients and is an independent predictor for mortality. Better recognition of clinically important thresholds is necessary. Increased intra-abdominal pressure (IAP) is associated with renal dysfunction, and renal failure is one of the most consistently described organ dysfunctions associated with IAH. Obesity is also associated with kidney injury. The underlying mechanisms are not yet fully understood. Increased IAP may be a link in this association. The aim of this study was firstly to find the range in values of intra-abdominal pressure (IAP) in cardiothoracic surgery patients a secondly to investigate the relationship between central obesity, body mass index (BMI) and IAP and thirdly to investigate the relationship between IAP, inflammation and renal function in this population.
Consecutive adult patients admitted to the cardiothoracic unit of the intensive care unit (ICU) after undergoing elective cardiothoracic surgery were included in this prospective, observational study. C-reactive protein (CRP) as a marker of inflammation and serum creatinine as a marker of renal function were measured pre- and postoperatively. Estimated glomerular filtration rates were calculated pre- and postoperatively. BMI was calculated. Waist circumference (WC), hip circumference (HC) and transvesical IAP were measured once directly after admission to the ICU postoperatively. Waist/hip ratio (WHR) was calculated (WC divided by HC). Three definitions of central obesity were used. Central obesity was defined according to WC, WHR or median WHR.
In total, 186 patients undergoing cardiothoracic surgery were included. Mean IAP was 9.1 mmHg (SD 4.4). IAP ≥ 12 mmHg was observed in 50 patients (26.9 %). IAP > 20 mmHg was measured in 4 patients (2.2 %). There was a positive correlation between IAP and BMI (r 2 = 0.05, p = 0.003). Correlations between IAP and WC (r 2 = 0.02, p = 0.054) and between IAP and WHR (r 2 = 0.01, p = 0.173) were not significant. There were no correlations between pre- or postoperative CRP and IAP (r 2 = 2.3 × 10−4, p = 0.839 and r 2 = 0.013, p = 0.117, respectively). In obese patients postoperative CRP was significantly higher than in non-obese patients (p = 0.034). There were no correlations between pre-operative serum creatinine and IAP (r 2 = 3.3 × 10−5, p = 0.938) or postoperative serum creatinine and IAP (r 2 = 0.003, p = 0.491).
The range in IAP in patients undergoing cardiothoracic surgery was wide. There was a positive correlation between IAP and BMI. Correlations between IAP and indices for central obesity were not significant. In a multiple regression model BMI was a better predictor of IAP than WHR in this population. There were no correlations between pre- or postoperative CRP and IAP. Furthermore, this study did not find evidence for a relation between IAP and pre- and postoperative serum creatinine.
Electronic supplementary material
The online version of this article (doi:10.1186/s13613-016-0195-8) contains supplementary material, which is available to authorized users.
PMCID: PMC5056912  PMID: 27726116
Intra-abdominal pressure; Central obesity; Waist/hip ratio; Waist circumference; Body mass index; Renal failure; Acute kidney injury
9.  Matching positive end-expiratory pressure to intra-abdominal pressure improves oxygenation in a porcine sick lung model of intra-abdominal hypertension 
Critical Care  2012;16(5):R208.
Intra-abdominal hypertension (IAH) causes atelectasis, reduces lung volumes and increases respiratory system elastance. Positive end-expiratory pressure (PEEP) in the setting of IAH and healthy lungs improves lung volumes but not oxygenation. However, critically ill patients with IAH often suffer from acute lung injury (ALI). This study, therefore, examined the respiratory and cardiac effects of positive end-expiratory pressure in an animal model of IAH, with sick lungs.
Nine pigs were anesthetized and ventilated (48 +/- 6 kg). Lung injury was induced with oleic acid. Three levels of intra-abdominal pressure (baseline, 18, and 22 mmHg) were randomly generated. At each level of intra-abdominal pressure, three levels of PEEP were randomly applied: baseline (5 cmH2O), moderate (0.5 × intra-abdominal pressure), and high (1.0 × intra-abdominal pressure). We measured end-expiratory lung volumes, arterial oxygen levels, respiratory mechanics, and cardiac output 10 minutes after each new IAP and PEEP setting.
At baseline PEEP, IAH (22 mmHg) decreased oxygen levels (-55%, P <0.001) and end-expiratory lung volumes (-45%, P = 0.007). At IAP of 22 mmHg, moderate and high PEEP increased oxygen levels (+60%, P = 0.04 and +162%, P <0.001) and end-expiratory lung volume (+44%, P = 0.02 and +279%, P <0.001) and high PEEP reduced cardiac output (-30%, P = 0.04). Shunt and dead-space fraction inversely correlated with oxygen levels and end-expiratory lung volumes. In the presence of IAH, lung, chest wall and respiratory system elastance increased. Subsequently, PEEP decreased respiratory system elastance by decreasing chest wall elastance.
In a porcine sick lung model of IAH, PEEP matched to intra-abdominal pressure led to increased lung volumes and oxygenation and decreased chest wall elastance shunt and dead-space fraction. High PEEP decreased cardiac output. The study shows that lung injury influences the effects of IAH and PEEP on oxygenation and respiratory mechanics. Our findings support the application of PEEP in the setting of acute lung injury and IAH.
PMCID: PMC3682312  PMID: 23098278
10.  The Effect of Intra-Abdominal Hypertension Incorporating Severe Acute Pancreatitis in a Porcine Model 
PLoS ONE  2012;7(3):e33125.
Abdominal compartment syndrome (ACS) and intra abdominal hypertension(IAH) are common clinical findings in patients with severe acute pancreatitis(SAP). It is thought that an increased intra abdominal pressure(IAP) is associated with poor prognosis in SAP patients. But the detailed effect of IAH/ACS on different organ system is not clear. The aim of this study was to assess the effect of SAP combined with IAH on hemodynamics, systemic oxygenation, and organ damage in a 12 h lasting porcine model.
Measurements and Methods
Following baseline registrations, a total of 30 animals were divided into 5 groups (6 animals in each group): SAP+IAP30 group, SAP+IAP20 group, SAP group, IAP30 group(sham-operated but without SAP) and sham-operated group. We used a N2 pneumoperitoneum to induce different levels of IAH and retrograde intra-ductal infusion of sodium taurocholate to induce SAP. The investigation period was 12 h. Hemodynamic parameters (CO, HR, MAP, CVP), urine output, oxygenation parameters(e.g., SvO2, PO2, PaCO2), peak inspiratory pressure, as well as serum parameters (e.g., ALT, amylase, lactate, creatinine) were recorded. Histological examination of liver, intestine, pancreas, and lung was performed.
Main Results
Cardiac output significantly decreased in the SAP+IAH animals compared with other groups. Furthermore, AST, creatinine, SUN and lactate showed similar increasing tendency paralleled with profoundly decrease in SvO2. The histopathological analyses also revealed higher grade injury of liver, intestine, pancreas and lung in the SAP+IAH groups. However, few differences were found between the two SAP+IAH groups with different levels of IAP.
Our newly developed porcine SAP+IAH model demonstrated that there were remarkable effects on global hemodynamics, oxygenation and organ function in response to sustained IAH of 12 h combined with SAP. Moreover, our model should be helpful to study the mechanisms of IAH/ACS-induced exacerbation and to optimize the treatment strategies for counteracting the development of organ dysfunction.
PMCID: PMC3293917  PMID: 22403734
11.  Intra-abdominal hypertension in cardiac surgery 
The occurrence of intra-abdominal hypertension (IAH), as well as its promoting factors in cardiac surgery, has been poorly explored. The aim of the present study was to characterize intra-abdominal pressure (IAP) variations in patients undergoing cardiac surgical procedures, and to identify the risk factors for IAH in this setting.
All consecutive adult patients requiring postoperative intensive care unit admission for >24 h were enrolled. Demographic data, pre-existing comorbidities, type and duration of surgery, cardiopulmonary bypass (CPB) use and duration, perioperative IAP, organ function and fluid balance were recorded. IAH was defined as a sustained increase in IAP >12 mmHg. Multivariate logistic regression and stepwise analyses identified the baseline and perioperative variables associated with IAH.
Of 69 patients, 22 (31.8%) developed IAH. In the logistic model, baseline IAP, high central venous pressure, vasoactive drugs administration, positive fluid balance, AKI, CPB, total sequential organ failure assessment score and age were all promoting factors for IAH (Hosmer–Lemeshow χ2 = 7.23; P = 0.843). Baseline IAP, high central venous pressure and positive fluid balance were independent risk factors for IAH in the stepwise analysis. The ROC curve analysis, obtained by plotting the occurrence of IAH vs the IAP baseline value, showed an AUC of 0.75 (SE 0.064; 99% CI 0.62–0.87; P < 0.0001). The best IAP cut-off value was at 8 mmHg (sensitivity 63% and specificity 76%). Considering on- and off-pump surgery groups, fluid balance and vasoactive drugs use were significantly higher in the on-pump group. Linear regression analysis showed a positive correlation (P = 0.0001) between IAP changes and fluid balance only in the on-pump group.
IAH develops in one-third of cardiac surgery patients and is strongly associated with higher baseline IAP values, higher central venous pressure, positive fluid balance, extracorporeal circulation, use of vasoactive drugs and AKI. Determinants of IAH should be accurately assessed before and after surgery, and patients presenting risk factors must be monitored properly during the perioperative period. In this context, the baseline value of IAP may be a valuable and early warning parameter for IAH occurrence.
PMCID: PMC3781798  PMID: 23820668
Intra-abdominal pressure; Abdominal hypertension; Cardiac surgery; Cardiac surgical patients; Acute kidney injury
12.  Effects of positive end-expiratory pressure on respiratory function and hemodynamics in patients with acute respiratory failure with and without intra-abdominal hypertension: a pilot study 
Critical Care  2009;13(5):R160.
To investigate the effects of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) with normal intra-abdominal pressure (IAP < 12 mmHg) and with intra-abdominal hypertension (IAH, defined as IAP ≥ 12 mmHg) during lung protective ventilation and a decremental PEEP, a prospective, observational clinical pilot study was performed.
Twenty patients with ALI/ARDS with normal IAP or IAH treated in the surgical intensive care unit in a university hospital were studied. The mean IAP in patients with IAH and normal IAP was 16 ± 3 mmHg and 8 ± 3 mmHg, respectively (P < 0.001). At different PEEP levels (5, 10, 15, 20 cmH2O) we measured respiratory mechanics, partitioned into its lung and chest wall components, alveolar recruitment, gas-exchange, hemodynamics, extravascular lung water index (EVLWI) and intrathoracic blood volume index (ITBVI).
We found that ALI/ARDS patients with IAH, as compared to those with normal IAP, were characterized by: a) no differences in gas-exchange, respiratory mechanics, partitioned into its lung and chest wall components, as well as hemodynamics and EVLWI/ITBVI; b) decreased elastance of the respiratory system and the lung, but no differences in alveolar recruitment and oxygenation or hemodynamics, when PEEP was increased at 10 and 15cmH2O; c) at higher levels of PEEP, EVLWI was lower in ALI/ARDS patients with IAH as compared with those with normal IAP.
IAH, within the limits of IAP measured in the present study, does not affect interpretation of respiratory mechanics, alveolar recruitment and hemodynamics.
PMCID: PMC2784387  PMID: 19804634
13.  Early recognition of abdominal compartment syndrome in patients with acute pancreatitis 
AIM: To assess the value of widely used clinical scores in the early identification of acute pancreatitis (AP) patients who are likely to suffer from intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS).
METHODS: Patients (n = 44) with AP recruited in this study were divided into two groups (ACS and non-ACS) according to intra-abdominal pressure (IAP) determined by indirect measurement using the transvesical route via Foley bladder catheter. On admission and at regular intervals, the severity of the AP and presence of organ dysfunction were assessed utilizing different multifactorial prognostic systems: Glasgow-Imrie score, Acute Physiology and Chronic Health Evaluation II (APACHE-II) score, and Multiorgan Dysfunction Score (MODS). The diagnostic performance of scores predicting ACS development, cut-off values and specificity and sensitivity were established using receiver operating characteristic (ROC) curve analysis.
RESULTS: The incidence of ACS in our study population was 19.35%. IAP at admission in the ACS group was 22.0 (18.5-25.0) mmHg and 9.25 (3.0-12.4) mmHg in the non-ACS group (P < 0.01). Univariate statistical analysis revealed that patients in the ACS group had significantly higher multifactorial clinical scores (APACHE II, Glasgow-Imrie and MODS) on admission and higher maximal scores during hospitalization (P < 0.01). ROC curve analysis revealed that APACHE II, Glasgow-Imrie, and MODS are valuable tools for early prediction of ACS with high sensitivity and specificity, and that cut-off values are similar to those used for stratification of patients with severe acute pancreatitis (SAP).
CONCLUSION: IAH and ACS are rare findings in patients with mild AP. Based on the results of our study we recommend measuring the IAP in cases when patients present with SAP (APACHE II > 7; MODS > 2 or Glasgow-Imrie score > 3).
PMCID: PMC2653440  PMID: 19222096
Acute pancreatitis; Abdominal compartment syndrome; Intra-abdominal pressure; Intra-abdominal hypertension; Organ dysfunction
14.  Mild to moderate intra-abdominal hypertension: Does it matter? 
This review summarizes the epidemiology, pathophysiological consequences and impact on outcome of mild to moderate (Grade I to II) intra-abdominal hypertension (IAH), points out possible pitfalls in available treatment recommendations and focuses on tasks for future research in the field. IAH occurs in about 40% of ICU patients. Whereas the prevalence of abdominal compartment syndrome seems to be decreasing, the prevalence of IAH does not. More than half of IAH patients present with IAH grade I and approximately a quarter with IAH grade II. However, most of the studies have addressed IAH as a yes-or-no variable, with little or no attention to different severity grades. Even mild IAH can have a negative impact on tissue perfusion and microcirculation and be associated with an increased length of stay and duration of mechanical ventilation. However, the impact of IAH and its different grades on mortality is controversial. The influence of intra-abdominal pressure (IAP) on outcome most likely depends on patient and disease characteristics and the concomitant macro- and microcirculation. Therefore, management might differ significantly. Today, clear triggers for interventions in different patient groups with mild to moderate IAH are not defined. Further studies are needed to clarify the clinical importance of mild to moderate IAH identifying clear triggers for interventions to lower the IAP.
PMCID: PMC4733462  PMID: 26855899
Intra-abdominal pressure; Intra-abdominal hypertension; Pathophysiology; Epidemiology; Severity; Treatment
15.  Effect of mechanical ventilation on intra-abdominal pressure in critically ill patients without other risk factors for abdominal hypertension: an observational multicenter epidemiological study 
Annals of Intensive Care  2012;2(Suppl 1):S22.
Mechanical ventilation (MV) is considered a predisposing factor for increased intra-abdominal pressure (IAP), especially when positive end-expiratory pressure (PEEP) is applied or in the presence of auto-PEEP. So far, no prospective data exists on the effect of MV on IAP. The study aims to look on the effects of MV on IAP in a group of critically ill patients with no other risk factors for intra-abdominal hypertension (IAH).
An observational multicenter study was conducted on a total of 100 patients divided into two groups: 50 patients without MV and 50 patients with MV. All patients were admitted to the intensive care units of the Medical and Surgical Research Centre, the Carlos J. Finlay Hospital, the Julio Trigo University Hospital, and the Calixto García Hospital, in Havana, Cuba between July 2000 and December 2004. The IAP was measured twice daily on admission using a standard transurethral technique. IAH was considered if IAP was greater than 12 mmHg. Correlations were made between IAP and body mass index (BMI), diagnostic category, gender, age, and ventilatory parameters.
The mean IAP in patients on MV was 6.7 ± 4.1 mmHg and significantly higher than in patients without MV (3.6 ± 2.4 mmHg, p < 0.0001). This difference was maintained regardless of gender, age, BMI, and diagnosis. The use of MV and BMI were independent predictors for IAH for the whole population, while male gender, assisted ventilation mode, and the use of PEEP were independent factors associated with IAH in patients on MV.
In this study, MV was identified as an independent predisposing factor for the development of IAH. Critically ill patients, which are on MV, present with higher IAP values on admission and should be monitored very closely, especially if PEEP is applied, even when they have no other apparent risk factors for IAH.
PMCID: PMC3527157  PMID: 23281625
16.  Prophylactic open abdomen in patients with postoperative intra-abdominal hypertension 
Critical Care  2010;14(1):111.
Postoperative intra-abdominal hypertension (IAH) is a frequent occurrence in critically ill patients operated on for severe abdominal trauma, secondary peritonitis or ruptured abdominal aortic aneurysm. IAH may progress to abdominal compartment syndrome (ACS) with new-onset organ dysfunction. Early recognition of IAH and interventions that prevent the development of ACS may preserve vital organ functions and increase the probability of survival. The best method to prevent postoperative ACS is to leave the abdomen open during the operation. The decision to leave the abdomen open is usually based on the surgeon's judgment without intra-abdominal pressure (IAP) measurements during the operation. Because significant morbidity and mortality are associated with the open abdomen, the measurement of IAP immediately after the fascial closure, when feasible, could offer an objective method for determining the optimal IAP threshold for leaving the abdomen open. The management of the open abdomen requires a temporary abdominal closure (TAC) system that would ideally prevent the development of ACS and facilitate later primary fascia closure. Among several TAC systems, the most promising are those that provide negative pressure to the wound or continuous fascial traction or both.
PMCID: PMC2875490  PMID: 20156323
17.  Intra-abdominal hypertension and the abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome 
Intensive Care Medicine  2013;39(7):1190-1206.
To update the World Society of the Abdominal Compartment Syndrome (WSACS) consensus definitions and management statements relating to intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS).
We conducted systematic or structured reviews to identify relevant studies relating to IAH or ACS. Updated consensus definitions and management statements were then derived using a modified Delphi method and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, respectively. Quality of evidence was graded from high (A) to very low (D) and management statements from strong RECOMMENDATIONS (desirable effects clearly outweigh potential undesirable ones) to weaker SUGGESTIONS (potential risks and benefits of the intervention are less clear).
In addition to reviewing the consensus definitions proposed in 2006, the WSACS defined the open abdomen, lateralization of the abdominal musculature, polycompartment syndrome, and abdominal compliance, and proposed an open abdomen classification system. RECOMMENDATIONS included intra-abdominal pressure (IAP) measurement, avoidance of sustained IAH, protocolized IAP monitoring and management, decompressive laparotomy for overt ACS, and negative pressure wound therapy and efforts to achieve same-hospital-stay fascial closure among patients with an open abdomen. SUGGESTIONS included use of medical therapies and percutaneous catheter drainage for treatment of IAH/ACS, considering the association between body position and IAP, attempts to avoid a positive fluid balance after initial patient resuscitation, use of enhanced ratios of plasma to red blood cells and prophylactic open abdominal strategies, and avoidance of routine early biologic mesh use among patients with open abdominal wounds. NO RECOMMENDATIONS were possible regarding monitoring of abdominal perfusion pressure or the use of diuretics, renal replacement therapies, albumin, or acute component-parts separation.
Although IAH and ACS are common and frequently associated with poor outcomes, the overall quality of evidence available to guide development of RECOMMENDATIONS was generally low. Appropriately designed intervention trials are urgently needed for patients with IAH and ACS.
Electronic supplementary material
The online version of this article (doi:10.1007/s00134-013-2906-z) contains supplementary material, which is available to authorized users.
PMCID: PMC3680657  PMID: 23673399
Intra-abdominal hypertension; Abdominal compartment syndrome; Critical care; Grading of Recommendations, Assessment, Development, and Evaluation; Evidence-based medicine; World Society of the Abdominal Compartment Syndrome
18.  The duration of intra-abdominal hypertension strongly predicts outcomes for the critically ill surgical patients: a prospective observational study 
Intra-abdominal hypertension (IAH) is associated with morbidity and mortality in critically ill patients. The present study analyzed the clinical significance of IAH in surgical patients with severe sepsis.
This was a prospective study carried out in the surgical intensive care unit (SICU). Intra-abdominal pressure (IAP) was measured three times a day via a urinary catheter filled with 25 mL of saline. IAH was defined as an IAP ≥ 12 mmHg, and the peak IAP was recorded as the IAP for the day. Data were analyzed in terms of IAH development and the IAH duration.
Of the 46 patients enrolled in the study, 42 developed IAH while in the SICU. The development of IAH aggravated the clinical outcomes; such as longer SICU stay, requirement of ventilator support, and delayed initiation of enteral feeding (EF). The IAH duration showed a significant correlation with pulmonary, renal, and cardiovascular function, and enteral feeding. The IAH duration was an independent predictor of 60-day mortality (odds ratio: 1.196; p = 0.014).
The duration of IAH is a more important prognostic factor than the development of IAH; thus every effort should be made to reduce the IAH duration in critically ill patients.
Trial registration
PMCID: PMC4459464  PMID: 26056530
Severe sepsis; Intra-abdominal hypertension; Intra-abdominal pressure; Enteral feeding, abdominal perfusion pressure
19.  Abdominal Compartment Syndrome and Intra-abdominal Ischemia in Patients with Severe Acute Pancreatitis 
World Journal of Surgery  2016;40:1454-1461.
Severe acute pancreatitis may be complicated by intra-abdominal hypertension (IAH), abdominal compartment syndrome (ACS), and intestinal ischemia. The aim of this retrospective study is to describe the incidence, treatment, and outcome of patients with severe acute pancreatitis and ACS, in particular the occurrence of intestinal ischemia.
The medical records of all patients admitted with severe acute pancreatitis admitted to the ICU of a tertiary referral center were reviewed. The criteria proposed by the World Society of the Abdominal Compartment Syndrome (WSACS) were used to determine whether patients had IAH or ACS.
Fifty-nine patients with severe acute pancreatitis were identified. Intra-abdominal pressure (IAP) measurements were performed in 29 patients (49.2 %). IAH was present in all patients (29/29). ACS developed in 13/29 (44.8 %) patients. Ten patients with ACS underwent decompressive laparotomy. A large proportion of patients with ACS had intra-abdominal ischemia upon laparotomy: 8/13 (61.5 %). Mortality was high in both the ACS group and the IAH group.
This study confirms that ACS is common in severe acute pancreatitis. Intra-abdominal ischemia occurs in a large proportion of patients with ACS. Swift surgical intervention may be indicated when conservative measures fail in patients with ACS. National and international guidelines need to be updated so that routine IAP measurements become standard of care for patients with severe acute pancreatitis in the ICU.
PMCID: PMC4868862  PMID: 26830909
20.  Intra-abdominal hypertension; prevalence, incidence and outcomes in a low resource setting; a prospective observational study 
Intra-abdominal hypertension (IAH) is defined as a sustained elevation in intra-abdominal pressure (IAP) greater than or equal to 12 mmHg. IAH has been shown to cause organ derangements and dysfunction in the body. Objective screening of IAH is neither done early enough nor at all thus leading to significant morbidity and mortality among surgical patients. The epidemiology and outcome of IAH among surgical patients has not been documented in Uganda. The aim of this study was to determine the prevalence, incidence and outcome of intra-abdominal hypertension among patients undergoing emergency laparotomy.
Prospective observational study, conducted from January to April 2015 among patients undergoing emergency laparotomy. Inclusion criteria was; age >7 yrs, scheduled for emergency laparotomy, able to lie supine. Exclusion Criteria: pregnant, failed urethral catheterization, known cardiac, renal and respiratory disorders. Consecutive sampling was used. IAP, blood pressure, heart rate, respiratory rate, Sp02, Serum creatinine, Serum urea, and Urine output were measured preoperatively and postoperatively at 0, 6, 24 and 48 h. IAH was defined as IAP > 12 mmHg on three consecutive readings 3 min apart.
In total 192 patients were enrolled. Mean age ± SD was 14.25 (±3.16) yrs in the paediatrics and 34.4(±13.72) yrs in the adults with male preponderance 65 and 80.7 % respectively. The prevalence of IAH was 25 % paediatrics and 17.4 % adults and the cumulative incidence after surgery was 20 % paediatrics and 21 % adults. In paediatrics, IAH was associated with mortality at 0 h postoperatively, RRR = 1:24, 95 % CI (1.371–560.178), p-value 0.048. In adults, the statistically significant outcomes associated with IAH were respiratory system dysfunction RRR1:2.783, p-value 0.023, 95 % CI (1.148–6.744) preoperatively and mortality RRR 1:2.933, p-value 0.034, 95 % CI (1.017–8.464) at 6 h, RRR 1:3.769, p-value 0.033, 95 % CI (1.113–12.760) at 24 h postoperatively.
The prevalence and incidence of IAH in the paediatrics and adults group in our study population were high. IAH was associated with mortality in both adult and paediatrics groups and respiratory system dysfunction in adult group. This calls for objective monitoring of intraabdominal pressure in patients undergoing emergency laparotomy with the aim of reducing associated mortality.
PMCID: PMC4657315  PMID: 26604981
Intra-abdominal pressure; Intra-abdominal hypertension; Emergency laparotomy; Mortality
21.  Clinical review: Intra-abdominal hypertension: does it influence the physiology of prone ventilation? 
Critical Care  2010;14(4):232.
Prone ventilation (PV) is a ventilatory strategy that frequently improves oxygenation and lung mechanics in critical illness, yet does not consistently improve survival. While the exact physiologic mechanisms related to these benefits remain unproven, one major theoretical mechanism relates to reducing the abdominal encroachment upon the lungs. Concurrent to this experience is increasing recognition of the ubiquitous role of intra-abdominal hypertension (IAH) in critical illness, of the relationship between IAH and intra-abdominal volume or thus the compliance of the abdominal wall, and of the potential difference in the abdominal influences between the extrapulmonary and pulmonary forms of acute respiratory distress syndrome. The present paper reviews reported data concerning intra-abdominal pressure (IAP) in association with the use of PV to explore the potential influence of IAH. While early authors stressed the importance of gravitationally unloading the abdominal cavity to unencumber the lung bases, this admonition has not been consistently acknowledged when PV has been utilized. Basic data required to understand the role of IAP/IAH in the physiology of PV have generally not been collected and/or reported. No randomized controlled trials or meta-analyses considered IAH in design or outcome. While the act of proning itself has a variable reported effect on IAP, abundant clinical and laboratory data confirm that the thoracoabdominal cavities are intimately linked and that IAH is consistently transmitted across the diaphragm - although the transmission ratio is variable and is possibly related to the compliance of the abdominal wall. Any proning-related intervention that secondarily influences IAP/IAH is likely to greatly influence respiratory mechanics and outcomes. Further study of the role of IAP/IAH in the physiology and outcomes of PV in hypoxemic respiratory failure is thus required. Theories relating inter-relations between prone positioning and the abdominal condition are presented to aid in designing these studies.
PMCID: PMC2945095  PMID: 20804560
22.  Management of intra-abdominal hypertension and abdominal compartment syndrome: a review 
Patients in the intensive care unit (ICU) are at risk of developing of intra abdominal hypertension (IAH) and abdominal compartment syndrome (ACS).
Aim: This review seeks to define IAH and ACS, identify the aetiology and presentation of IAH and ACS, identify IAP measurement techniques, identify current management and discuss the implications of IAH and ACS for nursing practice. A search of the electronic databases was supervised by a health librarian. The electronic data bases Cumulative Index of Nursing and Allied Health Literature (CINAHL); Medline, EMBASE, and the World Wide Web was undertaken from 1996- January 2011 using MeSH and key words which included but not limited to: abdominal compartment syndrome, intra -abdominal hypertension, intra-abdominal pressure in adult populations met the search criteria and were reviewed by three authors using a critical appraisal tool. Data derived from the retrieved material are discussed under the following themes: (1) etiology of intra-abdominal hypertension; (2) strategies for measuring intra-abdominal pressure (3) the manifestation of abdominal compartment syndrome; and (4) the importance of nursing assessment, observation and interventions. Intra-abdominal pressure (IAP) and abdominal compartment syndrome (ACS) have the potential to alter organ perfusion and compromise organ function.
PMCID: PMC3925290  PMID: 24499574
Intra-abdominal pressure; Intra-abdominal hypertension; Abdominal compartment syndrome; Abdominal perfusion pressure
23.  Analyzing intra-abdominal pressures and outcomes in patients undergoing emergency laparotomy 
Studies have documented the impact of intra-abdominal hypertension (IAH) on virtually every organ. However, it still remains strangely underdiagnosed. The aims of the study were to assess, in patients undergoing emergency laparotomy, whether intra-abdominal pressure (IAP) is an independent predictor of morbidity and mortality, to evaluate the effects of IAH, and to identify hidden cases of abdominal compartment syndrome (ACS).
Materials and Methods:
The study comprised 197 patients undergoing emergency laparotomy. IAP was measured preoperatively and then postoperatively at 0, 6, and 24 hours. Duration of hospital stay, occurrence of burst abdomen, and mortality were noted as outcomes.
At admission, incidence of IAH was 80%. No significant association was found between IAP and occurrence of burst abdomen (P > 0.1). IAP was found to be a significant predictor of mortality in patients undergoing laparotomy (P < 0.001). Elevated IAP was found to affect all the organ systems adversely. The incidence of post-op ACS was 3.05% in the general population and 13.16% in trauma patients. The mortality rate for this subgroup was 100%.
IAP is a significant predictor of mortality in patients undergoing laparotomy. IAH has detrimental effects on various organ systems. A more frequent monitoring with prompt decompression may be helpful in decreasing the mortality rate. Further studies are required to establish a screening protocol in patients undergoing laparotomy to detect and manage cases of IAH and ACS.
PMCID: PMC2966562  PMID: 21063552
Abdominal compartment syndrome; intra-abdominal hypertension; intra-abdominal pressure
24.  Intra-abdominal pressure: Time ripe to revise management guidelines of acute pancreatitis? 
AIM: To systematically review evidence on pathophysiology of intra-abdominal pressure (IAP) in acute pancreatitis (AP) with its clinical correlates.
METHODS: Systematic review of available evidence in English literature with relevant medical subject heading terms on PubMed, Medline and Scopus with further search from open access sources on internet as suggested by articles retrieved.
RESULTS: Intra-abdominal hypertension (IAH) is increasingly gaining recognition as a point of specific intervention with potential to alter disease outcome and improve mortality in AP. IAH can be expected in at least 17% of patients presenting with diagnosis of AP to a typical tertiary care hospital (prevalence increasing to 50% in those with severe disease). Abdominal compartment syndrome can be expected in at least 15% patients with severe disease. Recent guidelines on management of AP do not acknowledge utility of surveillance for IAP other than those by Japanese Society of Hepato-Biliary-Pancreatic Surgery. We further outline pathophysiologic mechanisms of IAH; understanding of which advances our knowledge and helps to coherently align common observed variations in management related conundrums (such as fluid therapy, nutrition and antibiotic prophylaxis) with potential to further individualize treatment in AP.
CONCLUSION: We suggest that IAP be given its due place in future practice guidelines and that recommendations be formed with help of a broader panel with inclusion of clinicians experienced in management of IAH.
PMCID: PMC4753186  PMID: 26909242
Intra-abdominal hypertension; Abdominal compartment syndrome; Pancreatitis; Practice guideline
25.  Influence of two different levels of intra-abdominal hypertension on bacterial translocation in a porcine model 
Annals of Intensive Care  2012;2(Suppl 1):S17.
The purpose of the present study was to quantify bacterial translocation to mesenteric lymph nodes due to different levels of intra-abdominal hypertension (IAH; 15 vs. 30 mmHg) lasting for 24 h in a porcine model.
We examined 18 anesthetized and intubated pigs (52.3 ± 4.7 kg) which were randomly allocated to three experimental groups (each n = 6) and studied over a period of 24 h. After preparation and establishing a steady state, the intra-abdominal pressure (IAP) was increased stepwise to 30 mmHg in six animals using a carbon dioxide (CO2) insufflator (IAP-30 group). In the second group, IAP was increased to 15 mmHg (IAP-15 group), while IAP remained unchanged in another six pigs (control group). Using a pulse contour cardiac output (PiCCO®) monitoring system, hemodynamic parameters as well as blood gases were recorded periodically. Moreover, peripheral and portal vein blood samples were taken for microbiological examinations. Lymph nodes from the ileocecal junction were sampled during an intra-vital laparotomy at the end of the observational period. After sacrificing the animals, bowel tissue samples and corresponding mesenteric lymph nodes (MLN) were extracted for histopathological and microbiological analyses.
Cardiac output decreased in all groups. In IAP-30 animals, volumetric preload indices significantly decreased, while those of IAP-15 pigs did not differ from those of controls. Under IAH, the mean arterial pressure (MAP) in the IAP-30 group declined, while MAP in the IAP-15 group was significantly elevated (controls unchanged). PO2 and PCO2 remained unchanged. The grade of ischemic damage of the intestines (histopathologically quantified using the Park score) increased significantly with different IAH levels. Accordingly, the amount of translocated bacteria in intestinal wall specimens as well as in MLN significantly increased with the level of IAH. Lymph node cultures confirmed the relation between bacterial translocation (BT) and IAP. The most often cultivated species were Escherichia coli, Staphylococcus, Clostridium, Pasteurella, and Streptococcus. Bacteremia was detected only occasionally in all three groups (not significantly different) showing gut-derived bacteria such as Proteus, Klebsiella, and E. coli spp.
In this porcine model, a higher level of ischemic damage and more BT were observed in animals subjected to an IAP of 30 mmHg when compared to animals subjected to an IAP of 15 mmHg or controls.
PMCID: PMC3390291  PMID: 22873417
abdominal compartment syndrome; intra-abdominal hypertension; pneumoperitoneum; bacterial translocation; bowel; ischemia; histologic; mesenteric lymph node; pig; animal.

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