From the Guidelines
The surest value of increased intraabdominal pressure is 12 mmHg or higher, which is the threshold for diagnosing intraabdominal hypertension (IAH). This value is based on the most recent and highest quality study, which defines IAH as a sustained or repeated pathological elevation in IAP ≥ 12 mmHg 1. IAP should be measured using a standardized technique, typically via a bladder catheter with the patient in a supine position and the transducer zeroed at the level of the mid-axillary line. Normal IAP ranges from 5-7 mmHg in critically ill adults. IAH is graded in severity:
- Grade I (12-15 mmHg)
- Grade II (16-20 mmHg)
- Grade III (21-25 mmHg)
- Grade IV (>25 mmHg). When IAP exceeds 20 mmHg with evidence of new organ dysfunction, this constitutes abdominal compartment syndrome (ACS), a medical emergency requiring immediate intervention 1. Elevated IAP can compromise organ perfusion by reducing cardiac output, compressing renal vessels, and restricting diaphragmatic excursion, leading to multisystem dysfunction. Regular monitoring of IAP is essential in at-risk patients, including those with major abdominal surgery, massive fluid resuscitation, or conditions causing significant abdominal distension.
In terms of morbidity, mortality, and quality of life, early detection and management of IAH and ACS are crucial to prevent complications and improve outcomes 1. The experts suggest monitoring IAP in patients at risk of intra-abdominal pressure elevation to early detect abdominal compartment syndrome, and recommend admission to an institution with the 24/7 capacity to perform an emergency haemostatic laparotomy for at least the first 24 hours in a unit with continuous monitoring.
Therefore, the most appropriate answer is A. 12-15 mmHg, as it represents the threshold for diagnosing IAH and the starting point for grading its severity.
From the Research
Definition of Increased Intraabdominal Pressure
The surest value of increased intraabdominal pressure is defined as:
- Intra-abdominal hypertension (IAH) is diagnosed when the intra-abdominal pressure (IAP) is more than 12 mmHg 2, 3
- Abdominal compartment syndrome (ACS) is defined as IAP ≥ 20 mmHg (with or without an abdominal perfusion pressure < 60 mm Hg) that is associated with dysfunction or failure of one or more organ systems that was not previously present 3
Values of Increased Intraabdominal Pressure
The values of increased intraabdominal pressure are:
- IAH: more than 12 mmHg 2, 3
- ACS: ≥ 20 mmHg 3 Based on these values, the correct answer is:
- More than 25 mmHg is not the surest value, but rather a value that is higher than the defined threshold for ACS
- 20-25 mmHg includes the threshold for ACS, but is not the surest value
- 15-20 mmHg is below the threshold for ACS, but above the threshold for IAH
- 12-15 mmHg is the threshold for IAH, but not the surest value for increased intraabdominal pressure in general, as it does not account for ACS
Clinical Significance
Increased intraabdominal pressure can lead to: