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

Table 1 Definitions and diagnostic criteria for intra-abdominal hypertension/abdominal compartment syndrome

1	IAP is the steady-state pressure concealed within the abdominal cavity
2	APP = MAP - IAP
3	FG = GFP-PTP = MAP - 2 × IAP
4	IAP should be expressed in mmHg 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
5	The reference standard for intermittent IAP measurement is via the bladder with a maximal instillation volume of 25 mL of sterile saline
6	Normal IAP is approximately 5-7 mm Hg in critically ill adults
7	IAH is defined by a sustained or repeated pathologic elevation of IAP ≥ 12 mmHg
8	IAH is graded as follows:
	Grade I: IAP 12-15 mmHg
	Grade II: IAP 16-20 mmHg
	Grade III: IAP 21-25 mmHg
	Grade IV: IAP > 25 mmHg
9	ACS is defined as a sustained IAP > 20 mmHg (with or without an APP < 60 mmHg) that is associated with new organ dysfunction/failure
10	Primary ACS is a condition associated with injury or disease in the abdomino-pelvic region that frequently requires early surgical or interventional radiological intervention
11	Secondary ACS refers to conditions that do not originate from the abdomino-pelvic region
12	Recurrent ACS refers to the condition in which ACS redevelops following previous surgical or medical treatment of primary or secondary ACS

(Adapted with permission from Kirkpatrick et al[30]). ACS: Abdominal compartment syndrome; APP: Abdominal perfusion pressure; FG: Filtration gradient; GFP: Glomerular filtration pressure; IAH: Intra-abdominal hypertension; IAP: Intra-abdominal pressure; MAP: Mean arterial pressure; PTP: Proximal tubular pressure.