|About Us||Patients, Families & Visitors||For Health Professionals||Careers||Research & Training||Ways to Give|
It is the measurement of the pressure inside the abdominal compartment.
Normal Intra-abdominal Pressure (IAP) is 0 - 5 mmHg; 5-7 mmHg during critical illness.
Intra-abdominal Hypertension (IAH) is defined by pressures > 12 mmHg (may be sufficient to restrict perfusion to the organs of the gut)
Abdominal Compartment Syndrome (ACS) is defined as sustained pressures > 20 mmHg with evidence of organ dysfunction. General surgery notification should be considered and lactate monitored closely.
IAH is graded as follows:
Grade I: IAP 12–15 mmHg
Grade II: IAP 16–20 mmHg
Grade III: IAP 21–25 mmHg
Abdominal compliance refers to the ability of the abdominal compartment to accommodate volume and is influenced by the elasticity of the abdominal wall and diaphragm. It should is expressed as the change in intra-abdominal volume per change in IAP
Abdominal Perfusion Pressure (APP) should be > 60 mmHg and is defined as:
APP = MAP – IAP
APP is dependent upon an adequate MAP and low IAP
Primary IAH or ACS is the result of abdominopelvic injury or disease and often requires surgical or interventional radiology treatment
Secondary IAH or ACS is the result of conditions that originate outside the abdominopelvic region (e.g., systemic inflammation)
Pressure may rise rapidly with active bleeding. Edema (which occurs with any ischemic insult) will generally result in a later rise in the pressure (27 hours or more post insult)
Polycompartment syndrome is a condition where two or more anatomical compartments have elevated pressures
An open abdomen is a method for surgical decompression that requires a temporary abdominal wound closure because the skin and fascia have been left open.
Lateralization of the abdominal wall is a phenomenon where the musculature and fascia of the abdominal wall moves laterally away from the midline
How is it measured?
can be measured directly by inserting a catheter into the abdominal compartment,
or indirectly, by monitoring the pressure in the bladder, stomach or other
The simplest and most frequently used method is to measure bladder pressure from an indwelling Foley catheter.
Why is it done?
All patients who are edematous, critically ill or who have abdomonal distension for any reason are at risk. ARDS, intraabdominal disorders and inflammatory states are important risk factors.
The pressure inside the abdominal compartment can increase following trauma, as a result of the accumulation of blood, fluid or edema. Non-traumatic bowel ischemia/infarction or gastrointestinal hemorrhage can also lead to increased pressure in the abdominal compartment as ischemic cells swell or fluids collect. Coagulopathies with abdominal bleeding, cirrhosis, or profound hypothermia are other potential causes. Once the pressure in the abdominal compartment overcomes the pressure inside the capillaries that are responsible for perfusing the organs, ischemia and infarction of organs can occur.
Abdominal compartment pressure monitoring is done to help recognize life threatening elevations in pressure before ischemia or infarction of the abdominal organs occurs. When a patient exhibits a distended and taut abdomen, the measurement of abdominal compartment pressure can provide direction regarding the need for decompressive surgery.
compartment syndrome pressure can be measured very quickly, by hooking
a pressure monitoring system up to the luer lock connection of the drainage collecting tubing. Measurement via the drainage tubing sampling port (versus catheter) allows measurements from any catheter that is connected to continuous drainage.
The pressure monitoring circuit can be left connected to avoid opening of a closed circuit. Intermittent connection is often preferred to facility patient care/turning.
If the circuit is intermittently connected for pressure monitoring, it is important to ensure aseptic technique is maintained. The sampling port should be covered with an alcohol-based cap (like IV connections) and the ends of any tubing/syringes are kept sterile.
Prior to measuring pressure, the bladder should be empty. A volume of 25 ml of saline should be instilled into the empty bladder to allow pressure to facilitate pressure wave transmission while maintaining a constant bladder volume with each measurement.
All pressures should be taken with the patient lying supine, head flat and transducer level confirmed. Each measurement should be taken at end expiration.
|Figure 1: Set up showing syringe connected to stopcock on pressure tubing. End of pressure tubing is connected to luer lock sampling port on drainage tubing.|
Key Points for Accurate Measurement
Risk Factors for Intra-abdominal Hypertension (from Kirkpatrick 2013):
Diminished abdominal wall compliance
Increased intra-luminal contents
Increased intra-abdominal contents
Hemoperitoneum/pneumoperitoneum or intra-peritoneal fluid
Intra-abdominal or retroperitoneal tumors
Laparoscopy with excessive insufflation pressures
Liver dysfunction/cirrhosis with ascites
Capillary leak/fluid resuscitation
Damage control laparotomy
Increased APACHE-II or SOFA score
Massive fluid resuscitation or positive fluid balance
Increased head of bed angle
Massive incisional hernia repair
Obesity or increased body mass index
Shock or hypotension
Reduce abdominal wall tension:
Position patient to lower intra-abdominal pressures:
Reduce intralumen gastrointestinal contents:
Evacuation of intra-abdominal contents:
Optimize fluid balance and maintain an adequate abdominal perfusion pressure:
Maintain an adequate abdominal perfusion pressure and use goal directed resuscitation:
Modified classification scheme for the complexity of the open abdomen (Bjorck, 2016)
Open abdomen is classified according to whether there is “fixed”, if there is contamination and the degree of contamination.
Fixation refers to the mechanical properties of the abdomen. A “fixed” abdomen has adhesions between the abdominal wall and contents that impair elasticity and compliance.
1 No Fixation
1A: No fixation
1B: Clean, no fixation
1C: Enteric leak, no fixation
2 Developing fixation
2A: Clean, developing fixation
2B: Contaminated, developing fixation
2C: Enteric leak, developing fixation
3 Frozen abdomen
3A: Clean, frozen abdomen
3B: Contaminated, frozen abdomen
4 Established enteroatmospheric fistula, frozen abdomen
What findings may indicate organ dysfunction?
Patients with abdominal compartment syndrome should be monitored for the following:
The most common findings of abdominal compartment syndrome are renal and cardiopulmonary complications. In head injury, increased abdominal compartment pressure can increase ICP. Monitoring for abdominal compartment syndrome in patients who are at risk for intracranial and intra-abdominal hypertension is important.
Clinical Educator, CCTC
Revised: January 8, 2018
Bjorck, M., et al. (2016). Amended classification of the open abdomen. Scandinavian Journal of Surgery. Mar;105(1):5-10.
Bloomfield, G., Saggi, B., Blocher, C, & Sugerman, H. (1999). Physiologic effects of externally applied continuous negative abdominal pressure for intra-abdominal hypertension. Journal of Trauma: Injury, Infection and Critical Care. Jun; 46(6): 1014-6.
Cheatham, M. et al. (2007). Results from the international conference on experts on intra-abdominal hypertension and abdominal compartment syndrome. II Recommendation. Intensive Care Medicine. 33:961-962.
Cheatham, M., et al., (2007). The impact of body position on intra-abdominal pressure
measurement: A multicenter analysis. Crit Care Medicine, 37(7), 2187-90.
Diebel, L., Dulchavsky & S., Brown, W. (1997). Splanchnic ischemia and bacterial translocation in the abdominal compartment syndrome. Journal of Trauma: Injury, Infection and Critical Care. Nov; 43(5): 852-5.
Ivatury, R., et al. (1998). Intra-abdominal hypertension after life-threatening penetrating abdominal trauma: prophylaxis, incidence, and clinical relevance to gastric mucosal pH and abdominal compartment syndrome. Journal of Trauma: Injury, Infection and Critical Care. Jun; 44(6): 1016-23.
Kirkpatrick, A. et al. (2013). 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. 39:1190-1206.
Malbrain, M. et al. (2006) Results from teh international conference of experts on intra-abdominal hypertension and abdominal compartment syndrome. Intensive Care Med, 32:1722–1732
Milanesi, R and Caregnato, RC. (2016). Intra-abdominal pressure: An integrated review. Einstein. 14(3): 423-30.
Offner, P. & Burch, J. (1998). Abdominal compartment syndrome, part 1: presentation and workup: cardiopulmonary and renal findings are among the most prominent signs. Journal of Critical Illness. Oct; 13(10): 634-8.
Offner, P. & Burch, J. (1998). Abdominal compartment syndrome, part 2: management guidelines: which patients will require abdominal decompression? Journal of Critical Illness. Oct 13(10): 639-42.
Williams, M. & Simms, H. (1997). Abdominal compartment syndrome: case reports and implications for management in critically ill patients. American Surgeon. Jun; 63(6): 555-8.