Updated Abdominal Compartment Society Consensus Definitions (WSACS)

Expert Consensus On Definitions And Management Of Intra-Abdominal Hypertension And Abdominal Compartment Syndrome

An international team of experts is working on a project called updated WSACS consensus definitions. The goals of this study are to:

1. To generate expert consensus on the definitions and classification of IAH and ACS.
2. To generate expert consensus on definitions regarding the pathophysiology of IAH and ACS.
3. To generate consensus on definitions regarding the methods of measurement of intra-abdominal pressure (IAP).

Study Overview

• Status: Enrolling by invitation
• Conditions: Abdominal Compartment Syndrome; Abdominal Hypertension
• Intervention / Treatment: Other: Delphi study

Detailed Description

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are frequently encountered in critically ill or injured patients and remain associated with significant morbidity and mortality. IAH is defined as a sustained increase in intra-abdominal pressure (IAP) equal to or above 12 mmHg. It is diagnosed in approximately one-third of mixed medical and surgical intensive care unit (ICU) patients at admission and develops in about half during the first week of ICU stay. IAH has consistently been shown to be an independent predictor of adverse outcomes, including multi-organ dysfunction and death.

Following the original consensus definitions and subsequent guideline updates by the Abdominal Compartment Society (WSACS), the understanding and management of IAH and ACS have evolved substantially. While surgical etiologies such as trauma and ruptured abdominal aortic aneurysm were historically predominant, more recent data highlight that IAH and ACS frequently occur in medical ICU populations as well. Contributing factors include excessive fluid resuscitation, massive transfusion, venous congestion, and capillary leak, which can lead to secondary IAH and subsequent organ failure even in the absence of direct abdominal pathology.

Despite the availability of consensus guidelines and an improved understanding of the pathophysiology, it remains unclear whether prevention or active treatment of IAH directly improves patient outcomes. Furthermore, there is growing recognition of the need to refine the definitions, measurement techniques, and classification systems for IAH and ACS to reflect current clinical knowledge and practice across diverse healthcare settings.

The WSACS - The Abdominal Compartment Society - previously published comprehensive consensus definitions and recommendations in 2013. Since then, new research has provided additional insights into epidemiology, measurement technologies, classification systems, and the broader clinical implications of IAH and ACS. A recent global survey among healthcare professionals identified emerging areas of uncertainty and priority topics for definition updates.

In response, this study will conduct an international modified Delphi process to achieve expert consensus on updated definitions and clinical practice statements for IAH and ACS. The Delphi method will systematically collect and refine expert opinions over several iterative rounds, with the goal of reaching agreement on revised definitions, measurement approaches, pathophysiological frameworks, and classification criteria.

The outcome of this Delphi process will be a set of updated, evidence-informed, and globally endorsed definitions and recommendations for IAH, ACS, and the open abdomen. These consensus statements aim to harmonize terminology, support clinical decision-making, guide future research, and ultimately improve patient care. The target audience includes physicians, surgeons, intensivists, anesthesiologists, nurses, and policymakers involved in the management of critically ill or injured patients across both high- and low-to-middle-income countries.

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

Study Locations

• Poland
  • Lublin, Poland, 20090
    • Medical University of Lublin

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Inclusion Criteria: Panellists will be identified based on either of the following criteria At least 5 years of clinical experience as a staff member in Anesthesiology, Surgery or Intensive Care Medicine with involvement in care of patients with postoperative complications Author of at least one publication (observational studies or randomised controlled trials) on intra-abdominal hypertension or abdominal compartment syndrome. For patients and public involvement Individuals who have either personally experienced IAH or ACS following surgery or ICU within the last 5 years or, primary caregivers of such patients will be recruited as patient care representatives. Proficiency in English is required. To mitigate potential bias, patient care representatives mustn't maintain a professional or advisory relationship with the steering committee or panellists. Co-authors from previous WSACS survey published in 2024, former or current WSACS ambassadors, representative from WSES, ESAIC, ES

Description

Inclusion Criteria: Panellists will be identified based on either of the following criteria At least 5 years of clinical experience as a staff member in Anesthesiology, Surgery or Intensive Care Medicine with involvement in care of patients with postoperative complications Author of at least one publication (observational studies or randomised controlled trials) on intra-abdominal hypertension or abdominal compartment syndrome. For patients and public involvement Individuals who have either personally experienced IAH or ACS following surgery or ICU within the last 5 years or, primary caregivers of such patients will be recruited as patient care representatives. Proficiency in English is required. To mitigate potential bias, patient care representatives mustn't maintain a professional or advisory relationship with the steering committee or panellists. Co-authors from previous WSACS survey published in 2024, former or current WSACS ambassadors, representative from WSES, ESAIC, ESICM.

Exclusion Criteria:

• None

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Panelist	Other: Delphi study; structured interview via online survey

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Level of consensus on definitions of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS)	Proportion of predefined definition statements for IAH and ACS reaching consensus among expert panellists, measured using a structured Delphi process. Consensus is defined a priori as ≥80% agreement on a 5-point Likert scale (ratings of 4-5 indicating agreement). Outcomes will include: Number and percentage of statements reaching consensus Median and interquartile range (IQR) of Likert scores per statement Stability of responses across Delphi rounds	3-6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Level of consensus on pathophysiological concepts of IAH and ACS	Proportion of predefined pathophysiological statements related to IAH and ACS reaching consensus among expert panellists using a Delphi process. Consensus is defined as ≥80% agreement on a 5-point Likert scale. Outcomes will include: Number and percentage of statements reaching consensus Median and IQR of Likert scores per statement Changes in agreement across Delphi rounds	3-6 months
Level of consensus on measurement methods for intra-abdominal pressure (IAP)	Proportion of predefined statements regarding IAP measurement techniques reaching consensus among expert panellists using a Delphi process. Consensus is defined as ≥80% agreement on a 5-point Likert scale. Outcomes will include: Number and percentage of statements reaching consensus Median and IQR of Likert scores per statement Agreement trends across Delphi rounds	3-6 months

Collaborators and Investigators

• Sponsor: Medical University of Lublin
• Investigators: Principal Investigator: Prashant Nasa, MD, The Royal Wolverhampton NHS Trust Wolverhampton, UK

Publications and helpful links

General Publications

• Nasa P, Jain R, Juneja D. Delphi methodology in healthcare research: How to decide its appropriateness. World J Methodol. 2021 Jul 20;11(4):116-129. doi: 10.5662/wjm.v11.i4.116. eCollection 2021 Jul 20.
• Miller RS, Morris JA Jr, Diaz JJ Jr, Herring MB, May AK. Complications after 344 damage-control open celiotomies. J Trauma. 2005 Dec;59(6):1365-71; discussion 1371-4. doi: 10.1097/01.ta.0000196004.49422.af.
• Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, Shamseer L, Tetzlaff JM, Akl EA, Brennan SE, Chou R, Glanville J, Grimshaw JM, Hrobjartsson A, Lalu MM, Li T, Loder EW, Mayo-Wilson E, McDonald S, McGuinness LA, Stewart LA, Thomas J, Tricco AC, Welch VA, Whiting P, Moher D. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021 Mar 29;372:n71. doi: 10.1136/bmj.n71.
• Alhazzani W, Lewis K, Jaeschke R, Rochwerg B, Møller MH, Evans L, et al. Conflicts of interest disclosure forms and management in critical care clinical practice guidelines. Intensive Care Med. 2018;44(10):1691-8.
• Traversy G, Barnieh L, Akl EA, Allan GM, Brouwers M, Ganache I, et al. Managing conflicts of interest in the development of health guidelines. CMAJ. 2021;193(2):E49-E54.
• Schünemann HJ, Al-Ansary LA, Forland F, Kersten S, Komulainen J, Kopp IB, et al. Guidelines International Network: Principles for Disclosure of Interests and Management of Conflicts in Guidelines. Ann Intern Med. 2015;163(7):548-53.
• Gattrell WT, Logullo P, van Zuuren EJ, Price A, Hughes EL, Blazey P, et al. ACCORD (ACcurate COnsensus Reporting Document): A reporting guideline for consensus methods in biomedicine developed via a modified Delphi. PLoS Med. 2024;21(1):e1004326.
• Nasa P, Azoulay E, Khanna AK, Jain R, Gupta S, Javeri Y, et al. Expert consensus statements for the management of COVID-19-related acute respiratory failure using a Delphi method. Crit Care. 2021;25(1):106.
• Nasa P, Wise RD, Smit M, Acosta S, D'Amours S, Beaubien-Souligny W, et al. International cross-sectional survey on current and updated definitions of intra-abdominal hypertension and abdominal compartment syndrome. World J Emerg Surg. 2024;19(1):39.
• Roberts DJ, Zygun DA, Kirkpatrick AW, Ball CG, Faris PD, Bobrovitz N, et al. A protocol for a scoping and qualitative study to identify and evaluate indications for damage control surgery and damage control interventions in civilian trauma patients. BMJ Open. 2014;4(7):e005634.
• Higa G, Friese R, O'Keeffe T, Wynne J, Bowlby P, Ziemba M, et al. Damage control laparotomy: a vital tool once overused. J Trauma. 2010;69(1):53-9.
• van Brunschot S, Schut AJ, Bouwense SA, Besselink MG, Bakker OJ, van Goor H, et al. Abdominal compartment syndrome in acute pancreatitis: a systematic review. Pancreas. 2014;43(5):665-74.
• Strang SG, Van Lieshout EM, Breederveld RS, Van Waes OJ. A systematic review on intra-abdominal pressure in severely burned patients. Burns. 2014 Feb;40(1):9-16. doi: 10.1016/j.burns.2013.07.001. Epub 2013 Sep 17.
• Karkos CD, Menexes GC, Patelis N, Kalogirou TE, Giagtzidis IT, Harkin DW. A systematic review and meta-analysis of abdominal compartment syndrome after endovascular repair of ruptured abdominal aortic aneurysms. J Vasc Surg. 2014 Mar;59(3):829-42. doi: 10.1016/j.jvs.2013.11.085. Epub 2014 Jan 16.
• Malbrain ML, Chiumello D, Cesana BM, Reintam Blaser A, Starkopf J, Sugrue M, et al. A systematic review and individual patient data meta-analysis on intra-abdominal hypertension in critically ill patients: the wake-up project. World initiative on Abdominal Hypertension Epidemiology, a Unifying Project (WAKE-Up!). Minerva Anestesiol. 2014;80(3):293-306.
• Moll V, Khanna AK, Kurz A, Huang J, Smit M, Swaminathan M, et al. Optimization of kidney function in cardiac surgery patients with intra-abdominal hypertension: expert opinion. Perioper Med (Lond). 2024;13(1):72.
• Reintam Blaser A, Regli A, De Keulenaer B, Kimball EJ, Starkopf L, Davis WA, et al. Incidence, Risk Factors, and Outcomes of Intra-Abdominal Hypertension in Critically Ill Patients-A Prospective Multicenter Study (IROI Study). Crit Care Med. 2019;47(4):535-42.
• Regli A, Reintam Blaser A, De Keulenaer B, Starkopf J, Kimball E, Malbrain M, et al. Intra-abdominal hypertension and hypoxic respiratory failure together predict adverse outcome - A sub-analysis of a prospective cohort. J Crit Care. 2021;64:165-72.
• Strang SG, Van Lieshout EM, Van Waes OJ, Verhofstad MH. Prevalence and mortality of abdominal compartment syndrome in severely injured patients: A systematic review. J Trauma Acute Care Surg. 2016 Sep;81(3):585-92. doi: 10.1097/TA.0000000000001133.
• Kirkpatrick AW, Roberts DJ, De Waele J, Jaeschke R, Malbrain ML, De Keulenaer B, et al. 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 Med. 2013;39(7):1190-206.
• De Waele JJ, Cheatham ML, Malbrain MLNG, Kirkpatrick A, Sugrue M, Balogh Z, et al. Recommendations for research from the International Conference of Experts on Intra-abdominal Hypertension and Abdominal Compartment Syndrome. Acta Clin Belg. 2009;64(3):203-9.
• Cheatham ML. Nonoperative management of intraabdominal hypertension and abdominal compartment syndrome. World J Surg. 2009 Jun;33(6):1116-22. doi: 10.1007/s00268-009-0003-9.
• Cheatham ML, Malbrain ML, Kirkpatrick A, Sugrue M, Parr M, De Waele J, et al. Results from the International Conference of Experts on Intra-abdominal Hypertension and Abdominal Compartment Syndrome. II. Recommendations. Intensive Care Med. 2007;33(6):951-62.
• Malbrain ML, De laet I, Cheatham M. Consensus conference definitions and recommendations on intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS)--the long road to the final publications, how did we get there? Acta Clin Belg Suppl. 2007;62(1):44-59.
• Malbrain ML, Cheatham ML, Kirkpatrick A, Sugrue M, Parr M, De Waele J, et al. Results from the International Conference of Experts on Intra-abdominal Hypertension and Abdominal Compartment Syndrome. I. Definitions. Intensive Care Med. 2006;32(11):1722-32.
• Murphy PB, Parry NG, Sela N, Leslie K, Vogt K, Ball I. Intra-Abdominal Hypertension Is More Common Than Previously Thought: A Prospective Study in a Mixed Medical-Surgical ICU. Crit Care Med. 2018;46(6):958-64.
• Blaser AR, Sarapuu S, Tamme K, Starkopf J. Expanded measurements of intra-abdominal pressure do not increase the detection rate of intra-abdominal hypertension: a single-center observational study. Crit Care Med. 2014;42(2):378-86.

Helpful Links

• WSACS

Study record dates

Study Major Dates

• Study Start (Actual): October 13, 2025
• Primary Completion (Estimated): July 31, 2026
• Study Completion (Estimated): July 31, 2026

Study Registration Dates

• First Submitted: January 8, 2026
• First Submitted That Met QC Criteria: April 30, 2026
• First Posted (Actual): May 4, 2026

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 30, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: abdominal compartment syndrome; intra-abdominal pressure; pathophysiology; measurement; abdominal hypertension; definitions; intra-abdominal volume
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Vascular Diseases; Cardiovascular Diseases; Muscular Diseases; Compartment Syndromes; Intra-Abdominal Hypertension
• Other Study ID Numbers: MUL2025WSACS001; PROSPERO CRD420251167137 (Other Identifier: MULublin)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The IPD is available to investigators and can be shared with appropriate requests.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No