Surgical decompression for the management of abdominal compartment syndrome with severe acute pancreatitis: A narrative review

Intra-abdominal hypertension(IAH)and abdominal compartment syndrome(ACS)play a pivotal role in the pathophysiology of severe acute pancreatitis(SAP)and contribute to new-onset and persistent organ failure.The optimal management of ACS involves a multi-disciplinary approach,from its early recognition to measures aiming at an urgent reduction of intra-abdominal pressure(IAP).A targeted literature search from January 1,2000,to November 30,2022,revealed 20 studies and data was analyzed on the type and country of the study,patient demographics,IAP,type and timing of surgical procedure performed,post-operative wound management,and outcomes of patients with ACS.There was no randomized controlled trial published on the topic.Decom-pressive laparotomy is effective in rapidly reducing IAP(standardized mean difference=2.68,95%confidence interval:1.19-1.47,P<0.001;4 studies).The morbidity and complications of an open abdomen after decompressive laparotomy should be weighed against the inadequately treated but,potentially lethal ACS.Disease-specific patient selection and the role of less-invasive decompressive measures,like subcutaneous linea alba fasciotomy or component separation techniques,is lacking in the 2013 consensus management guidelines by the Abdominal Compartment Society on IAH and ACS.This narrative review focuses on the current evidence regarding surgical decompression techniques for managing ACS in patients with SAP.However,there is a lack of high-quality evidence on patient selection,timing,and modality of surgical decompression.Large prospective trials are needed to identify triggers and effective and safe surgical decompression methods in SAP patients with ACS.

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 ofthe 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.

Abdominal compartment syndrome:Often overlooked conditions in medical intensive care units

Intra-abdominal hypertension(IAH)and abdominal compartment syndrome are well recognized entities among surgical patients.Nevertheless,a number of prospective and retrospective observational studies have shown that IAH is prevalent in about half of the critically ill patients in the medical intensive care units(ICU)and has been widely recognized as an independent risk factor for mortality.It is alarming to note that many members of the critical care team in medical ICU are not aware of the consequences of untreated IAH and the delay in making the diagnosis leads to increased morbidity and mortality.Frequently it is underdiagnosed and undertreated in this patient population.Elevated intraabdominal pressure decreases the blood flow to the kidneys and other abdominal viscera and also results in reduced cardiac output and difficulties in ventilating the patient because of increased intrathoracic pressure.When intraabdominal hypertension is not promptly recognized and treated,it leads to abdominal compartment syndrome,multiorgan dysfunction syndrome and death.Large volume fluid resuscitation is very common in medical ICU patients presenting with sepsis,shock and other inflammatory conditions like pancreatitis and it is one of the major risk factors for the development of intra-abdominal hypertension.This article presents an overview of the epidemiology,definitions,risk factors,pathophysiology and management of IAH and abdominal compartment syndrome in critically ill medical ICU patients.

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 （η = 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 AR 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）.

Treatment of abdominal compartment syndrome in severe acute pancreatitis patients with traditional Chinese medicine

AIM: To investigate the therapeutic effect of traditional Chinese traditional medicines Da Cheng Qi Decoction (Timely-Purging and Yin-Preserving Decoction) and Glauber's salt combined with conservative measures on abdominal compartment syndrome (ACS) in severe acute pancreatitis (SAP) patients. METHODS: Eighty consecutive SAP patients, admitted for routine non-operative conservative treatment, were randomly divided into study group and control group (40 patients in each group). Patients in the study group received Da Cheng Qi Decoction enema for 2 h and external use of Glauber's salt, once a day for 7 d. Patients in the control group received normal saline (NS) enema. Routine non-operative conservative treatments included non-per os nutrition (NPON), gastrointestinal decompression, life support, total parenteral nutrition (TPN), continuous peripancreatic vascular pharmaceutical infusion and drug therapy. Intra-cystic pressure (ICP) of the two groups was measured during treatment. The effectiveness and outcomes of treatment were observed and APACHE Ⅱ scores were applied in analysis. RESULTS: On days 4 and 5 of treatment, the ICP was lower in the study group than in the control group(P < 0.05). On days 3-5 of treatment, acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) scores for the study and control groups were significantly different (P < 0.05). Both the effectiveness and outcome of the treatment with Da Cheng Qi Decoction on abdominalgia, burbulence relief time, ascites quantity, cyst formation rate and hospitalization time were quite different between the two groups (P < 0.05). The mortality rate for the two groups had no significant difference. CONCLUSION: Da Cheng Qi Decoction enema and external use of Glauber's salt combined with routine non-operative conservative treatment can decrease the intra-abdominal pressure (IAP) of SAP patients and have preventive and therapeutic effects on abdominal compartment syndrome of SAP.

Indwelling catheter and conservative measures in the treatment of abdominal compartment syndrome in fulminant acute pancreatitis

AIM： To study the effect of combined indwelling catheter, hemofiltration, respiration support and traditional Chinese medicine （e.g. Dahuang） in treating abdominal compartment syndrome of fulminant acute pancreatitis. METHODS： Patients with fulminant acute pancreatitis were divided randomly into 2 groups of combined indwelling catheter celiac drainage and intra-abdominal pressure monitoring and routine conservative measures group （group 1） and control group （group 2）. Routine non-operative conservative treatments including hemofiltration, respiration support, gastrointestinal TCM ablution were also applied in control group patients. Effectiveness of the two groups was observed, and APACHE Ⅱ scores were applied for analysis. RESULTS： On the second and fifth days after treatment, APACHE Ⅱ scores of group 1 and 2 patients were significantly different. Comparison of effectiveness （abdominalgia and burbulence relief time, hospitalization time） between groups 1 and 2 showed significant difference, as well as incidence rates of cysts formation. Mortality rates of groups 1 and 2 were 10.0% and 20.7%, respectively. For patients in group 1, celiac drainage quantity and intra-abdominal pressure, and hospitalization time were positively correlated （r = 0.552, 0.748, 0.923, P 〈 0.01） with APACHE Ⅱ scores. CONCLUSION： Combined indwelling catheter celiac drainage and intra-abdominal pressure monitoring, short veno-venous hemofiltration （SVVH）, gastrointestinal TCM ablution, respiration support have preventive and treatment effects on abdominal compartment syndrome of fulminant acute pancreatitis.

Embryonic natural orifice transluminal endoscopic surgery in the treatment of severe acute pancreatitis complicated by abdominal compartment syndrome

BACKGROUND: The study aimed to estimate the value of embryonal natural orifice transluminal endoscopic surgery(ENOTES) in treating severe acute pancreatitis(SAP) complicated with abdominal compartment syndrome(ACS).METHODS: The patients, who were randomized into an ENOTES group and an operative group, underwent ENOTES and laparotomy, respectively. The results and complications of the two groups were compared.RESULTS: Enterocinesia was observed earlier in the ENOTES group than in the operative group. Acute Physiology and Chronic Health Evaluation II(APACHE II) score of patients in the ENOTES group was lower than that of the operative group on the 1st, 3rd and 5th post-operative day(P<0.05). The cure rate was 96.87% in the ENOTES group, which was statistically different from 78.12% in the operative group(P<0.05). There were significant differences in complications and mortality between the two groups(P<0.01).CONCLUSION: Compared with surgical decompression, ENOTES associated with flexible endoscope therapy is an effective and minimal invasive procedure with less complications.

Abdominal compartment syndrome among surgical patients

Abdominal compartment syndrome(ACS)develops when organ failure arises secondary to an increase in intraabdominal pressure.The abdominal pressure is determined by multiple factors such as blood pressure,abdominal compliance,and other factors that exert a constant pressure within the abdominal cavity.Several conditions in the critically ill may increase abdominal pressure compromising organ perfusion that may lead to renal and respiratory dysfunction.Among surgical and trauma patients,aggressive fluid resuscitation is the most commonly reported risk factor to develop ACS.Other conditions that have also been identified as risk factors are ascites,hemoperitoneum,bowel distention,and large tumors.All patients with abdominal trauma possess a higher risk of developing intra-abdominal hypertension(IAH).Certain surgical interventions are reported to have a higher risk to develop IAH such as damage control surgery,abdominal aortic aneurysm repair,and liver transplantation among others.Close monitoring of organ function and intra-abdominal pressure(IAP)allows clinicians to diagnose ACS rapidly and intervene with target-specific management to reduce IAP.Surgical decompression followed by temporary abdominal closure should be considered in all patients with signs of organ dysfunction.There is still a great need for more studies to determine the adequate timing for interventions to improve patient outcomes.

Continuous regional arterial infusion and laparotomic decompression for severe acute pancreatitis with abdominal compartment syndrome

AIM:To evaluate the therapeutic effects of abdominal decompression plus continuous regional arterial infusion(CRAI) via a drug delivery system(DDS) in severe acute pancreatitis(SAP) patients with abdominal compartment syndrome(ACS).METHODS:We presented our recent experience in 8 patients with SAP.The patients developed clinical ACS,which required abdominal decompression.During the operation,a DDS was inserted into the peripancreatic artery(the catheter was inserted from the right gastroepiploic artery until it reached the junction between the pancreaticoduodenal and gastroduodenal artery).Through this DDS,a protease inhibitor,antibiotics and octreotide were infused continuously.The duration of the regional artery infusion ranged from 8 to 41 d.The outcomes and the changes in the APACHE Ⅱ score,computed tomography(CT) severity index and intraabdominal pressure(IAP) of the patients were retrospectively evaluated.RESULTS:Eight patients with an initial APACHE Ⅱ score of 18.9(range,13-27) and a Balthazar CT severity index of 9.1(range,7-10) developed severe local and systemic complications.These patients underwent subsequent surgical decompression and CRAI therapy because of intra-abdominal hypertension(IAH).After a mean interval of 131.9 ± 72.3 d hospitalization,7 patients recovered with decreased APACHE Ⅱ scores,CT severity indexes and IAP.The mean APACHE Ⅱ score was 5.4(range,4-8),the CT severity index was 2.3(range,1-3),and IAP decreased to 7.7 mmHg(range,6-11 mmHg) 60 d after operation.One patient died of multiple organ failure 1 wk after surgery.CONCLUSION:CRAI and laparotomic decompression might be a therapeutic option for SAP patients with ACS.

Should we perform decompressive laparotomy during severe acute pancreatitis with intra-abdominal hypertension below 25 mmHg:Only the gut knows

We suggest that during severe acute pancreatitis(SAP)with intra-abdominal hypertension,practitioners should consider decompressive laparotomy,even with intra-abdominal pressure(IAP)below 25 mmHg.Indeed,in this setting,non-occlusive mesenteric ischemia(NOMI)may occur even with IAP below this cutoff and lead to transmural necrosis if abdominal perfusion pressure is not promptly restored.We report our experience of 18 critically ill patients with SAP having undergone decompressive laparotomy of which one third had NOMI while IAP was mostly below 25 mmHg.

Airway Pressure Release Ventilation Improves Oxygenation in a Patient with Pulmonary Hypertension and Abdominal Compartment Syndrome

The following case describes the favorable application of airway pressure release ventilation (APRV) in a patient with pulmonary hypertension who developed respiratory failure and abdominal compartment syndrome after abdominal closure from an incarcerated umbilical hernia. A 66-year-old male with past medical history of restrictive lung disease, obstructive sleep apnea and pulmonary hypertension, presented to the operating room for an incarcerated inguinal hernia. After abdominal closure, he gradually developed decreased oxygen saturation and hypotension. APRV was initiated during post operative day 2 after inability to maintain adequate oxygen saturation with resultant hypotension on pressure control ventilation with varying degrees of positive end expiratory pressure and 100% inspired oxygen concentration. The initial set high pressure on APRV was 35 mm Hg. Yet, in lieu of decreasing lung compliance, it peaked at 50 mm Hg. Eventually, inhaled Nitric Oxide was initiated post operative day 3 due to increasing pulmonary arterial pressures. A bedside laparotomy was eventually performed when bladder pressures peaked to 25 mm Hg. APRV gradually and temporally improved the oxygen saturation and decreased the pulmonary arterial pressures with subsequent increase in systemic blood pressures. APRV promoted alveolar recruitment and decreased the shunting associated with abdominal compartment syndrome. Better oxygen saturations lead to increases in blood pressure by decreasing the effects of hypoxic pulmonary vasoconstriction on the right ventricle (RV). In patients with decreasing lung compliance and pulmonary comorbidities, APRV appears safe and allows for improve oxygenation, after failure with conventional modes of ventilation.

First Reported Incidence of Delayed Secondary Abdominal Compartment Syndrome in a Trauma Patient with Scleroderma: A Case Report and Review of the Literature

Background: Scleroderma is a complex immune-mediated rheumatic disease that is characterized by fibrosis of the skin, internal organs, and vasculopathy. Extensive fibrosis, especially in the limited compartment, has been reported to induce acute compartment syndrome frequently reported involving the upper and lower extremities. Case Presentation: We present a rare case of a 54-year-old Caucasian female who underwent surgery for abdominal compartment syndrome in the setting of scleroderma. Upon arrival, at the hospital, the patient’s health status showed signs of improvement with no indicators of abdominal compartment syndrome until the tenth hospital day. A CT scan showed a new intra-abdominal fluid collection with total lower abdominal anasarca and a stable retroperitoneal hematoma. Following emergency surgery, significant bowel edema without other intra-abdominal injuries was noted. Conclusion: Secondary abdominal compartment syndrome may occur in patients with scleroderma without evidence of intra-abdominal trauma or emergent abdominal surgery. Further research is warranted to investigate the relationship between scleroderma and secondary abdominal compartment syndrome.

EARLY SURGERY TO PATIENTS SUFFERING FULMINANT ACUTE PANCREATITIS WITH ABDOMINAL COMPARTMENT SYNDROME

Objective To retrospectively analyze and compare conservative versus surgical treatment of patients with fulminant acute pancreatitis (FAP) plus abdominal compartment syndrome (ACS). Methods From January 1998 to September 2005, 21 patients with FAP plus ACS were retrospectively analyzed. Ten patients were conservatively treated by means of intensive care medicine without surgery, and 11 patients received open surgical management and suction drainage. Results Seven of the 10 non-surgical patients died, comprising one with mild, four with moderate and two with severe ACS (70% mortality rate). Of the 11 patients receiving open surgical management in the early phase (within 3 days of disease initiation), three died, comprising one with moderate and two with severe ACS (27.3% mortality rate). The difference in mortality rates was found to be statistically significant. Conclusion Our data indicate patients suffering FAP with severe ACS should be treated with open management of the abdomen in the early phase (within 3 days), even in the absence of infection. This approach appears superior to that of conservative management. Surgical treatment resulted in abdominal decompression and subsequently significantly decreased the mortality rate and improved overall prognosis.

克罗恩病合并腹腔间隔室综合征:1例报道并文献复习

腹腔间隔室综合征(abdominal compartment syndrome,ACS)是临床中的一种急危症,死亡率较高。在此,我们报道1例克罗恩(Crohn’s disease,CD)患者,在病程进展中并发了ACS。此病例为国内外首次报道此种合并症,希望为临床医师提供参考。

横结肠癌术后并发ARDS和ACS患者1例的护理干预

目的:横结肠癌术后容易发生腹腔间隔室综合征(ACS)和急性呼吸窘迫综合征(ARDS)。对1例横结肠癌术后并发ARDS和ACS患者进行护理干预后病情得到控制,本文总结采用的护理干预方法。

Study of intra-abdominal hypertension prevalence and awareness level among experienced ICU medical staff

Background:Intra-abdominal hypertension(IAH) is a disease with high morbidity and mortality among critically ill patients.The study's objectives were to explore the prevalence of IAH and physicians' awareness of the 2013 World Society of Abdominal Compartment Syndrome(WSACS) guidelines in Chinese intensive care units(ICUs).Methods:A cross-sectional study of four ICUs in Southwestern China was conducted from June 17 to August 2,2014.Adult patients admitted to the ICU for more than 24 h,with bladder catheter but without obvious intravesical pressure(IVP) measurement contraindications,were recruited.Intensivists with more than 5 years of ICU working experience were also recruited.Epidemiological information,potential IAH risk factors,IVP measurements and questionnaire results were recorded.Results:Forty-one patients were selected.Fifteen(36.59%) had IVP?12mm Hg.SOFA(Sequential Organ Failure Assessment) hepatic and neurological sub-scores were utilized as independent predictors for IAH via logistic backward analysis.Thirty-seven intensivists participated in the survey(response rate:80.43%).The average score of each center was less than 35 points.All physicians believed the IAH prevalence in their departments was no more than 20.00%.A significant negative correlation was observed between the intensivists' awareness of the 2013 WSACS guidelines and the IAH prevalence in each center(r=-0.975,P=0.025).Conclusion:The prevalence and independent predictors of IAH among the surveyed population are similar to the reports in the literature.Intensivists generally have a low awareness of the 2013 WSACS guidelines.A systematic guideline training program is vital for improving the efficiency of the diagnosis and treatment of IAH.

Effect of laparoscopic abdominal surgery on splanchnic circulation: Historical developments

With the developments in medical technology and increased surgical experience, advanced laparoscopic surgical procedures are performed successfully. Laparoscopic abdominal surgery is one of the best examples of advanced laparoscopic surgery (LS). Today, laparoscopic abdominal surgery in general surgery clinics is the basis of all abdominal surgical interventions. Laparoscopic abdominal surgery is associated with systemic and splanchnic hemodynamic alterations. Inadequate splanchnic perfusion in critically ill patients is associated with increased morbidity and mortality. The underlying pathophysiological mechanisms are still not well understood. With experience and with an increase in the number and diversity of the resulting data, the pathophysiology of laparoscopic abdominal surgery is now better understood. The normal physiology and pathophysiology of local and systemic effects of laparoscopic abdominal surgery is extremely important for safe and effective LS. Future research projects should focus on the interplay between the physiological regulatory mechanisms in the splanchnic circulation (SC), organs, and diseases. In this review, we discuss the effects of laparoscopic abdominal surgery on the SC.

Elevated intra-abdominal pressure:A review of current knowledge

Elevated intra-abdominal pressure(IAP)is a known cause of increased morbidity and mortality among critically ill patients.Intra-abdominal hypertension(IAH)and abdominal compartment syndrome can lead to rapid deterioration of organ function and the development of multiple organ failure.Raised IAP affects every system and main organ in the human body.Even marginally sustained IAH results in malperfusion and may disrupt the process of recovery.Yet,despite being so common,this potentially lethal condition often goes unnoticed.In 2004,the World Society of the Abdominal Compartment Syndrome,an international multidisciplinary consensus group,was formed to provide unified definitions,improve understanding and promote research in this field.Simple,reliable and nearly costless standardized methods of non-invasive measurement and monitoring of bladder pressure allow early recognition of IAH and timely optimized management.The correct,structured approach to treatment can have a striking effect and fully restore homeostasis.In recent years,significant progress has been made in this area with the contribution of surgeons,internal medicine specialists and anesthesiologists.Our review focuses on recent advances in order to present the complex underlying pathophysiology and guidelines concerning diagnosis,monitoring and treatment of this life-threatening condition.

Intra-abdominal pressure:Time ripe to revise managementguidelines 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 Pub Med, 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-BiliaryPancreatic 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.

Noninvasive monitoring of intra-abdominal pressure by measuring abdominal wall tension

BACKGROUND: Noninvasive monitoring of intra-abdominal pressure(IAP) by measuring abdominal wall tension(AWT) was effective and feasible in previous postmortem and animal studies. This study aimed to investigate the feasibility of the AWT method for noninvasively monitoring IAP in the intensive care unit(ICU).METHODS: In this prospective study, we observed patients with detained urethral catheters in the ICU of Shanghai Tenth People's Hospital between April 2011 and March 2013. The correlation between AWT and urinary bladder pressure(UBP) was analyzed by linear regression analysis. The effects of respiratory and body position on AWT were evaluated using the paired samples t test, whereas the effects of gender and body mass index(BMI) on baseline AWT(IAP<12 mm Hg) were assessed using one-way analysis of variance.RESULTS: A total of 51 patients were studied. A significant linear correlation was observed between AWT and UBP(R=0.986, P<0.01); the regression equation was Y=–1.369+9.57X(P<0.01). There were signif icant differences among the different respiratory phases and body positions(P<0.01). However, gender and BMI had no signif icant effects on baseline AWT(P=0.457 and 0.313, respectively).CONCLUSIONS: There was a signif icant linear correlation between AWT and UBP and respiratory phase, whereas body position had signif icant effects on AWT but gender and BMI did not. Therefore, AWT could serve as a simple, rapid, accurate, and important method to monitor IAP in critically ill patients.