Monday, May 7, 2007

Monday May 07, 2007
Revisting Intra-Abdominal Hypertension (IAH)


Intra-Abdominal Hypertension (IAH) and Abdominal Compartment Syndrome (ACS) are encountered in critical care setting, which requires prompt identification and management.


DEFINITIONS

1. Intraabdominal pressure (IAP): The steady-state pressure concealed within the abdominal cavity.
2. Abdominal perfusion pressure (APP):


APP = MAP - IAP
* Mean arterial pressure (MAP)


3. Intra-abdominal Hypertension (IAH): IAH is defined by a sustained or repeated pathologic elevation of IAP >12 mmHg. Normal IAP is approximately 5-7 mmHg in critically ill adults.

4. Abdominal Compartment Syndrome (ACS): ACS defined as a sustained IAP > 20 mmHg (with or withou an APP less than 60 mmHg) that is associated with new organ dysfunction / failure.

HOW TO MEASURE

IAP should be expressed in mmHg (1 mmHg = 1.36 cmH2O) and measured at end-expiration in the complete supine position after ensuring that abdominal muscle contractions are absent and with the transducer zeroed at the level of the mid-axillary line. The reference standard for intermittent IAP measurement is via the bladder with a maximal instillation volume of 25 mL of sterile saline. Normal IAP is approximately 5-7 mmHg in critically ill adults.

GRADES of IAH:
Grade I , 12-15 mmHg
Grade II, 16-20 mmHg
Grade III, 21- 25 mm Hg
Grade IV, more than 25 mm Hg

Related web site: The World Society of the Abdominal Compartment Syndrome (WSACS)

See following diagram from commercially available product - AbViser® AutoValve™ - click on pic to get bigger image