Intra-Abdominal Pressure Monitor

Reviewed and revised 15 August 2014

OVERVIEW

• device used to assess intra-abdominal pressure (IAP)
• intra-abdominal pressure is the steady state pressure concealed within the abdominal cavity

USE

• measurement of intra-abdominal pressure in patients at risk of, or suspected of having, abdominal compartment syndrome

DESCRIPTION

• can be performed using proprietary devices
• requires pressure transducer set up connected to indwelling urinary catheter
• one approach is to cross-clamp the tubing of the drainage bag and insert a 16-gauge needle through the aspiration port, which is connected to a pressure transducer
• Alternatively, a T-piece connector or a three- way stopcock is inserted between the catheter and the drainage bag

METHOD OF USE

Intra-abdominal pressure measurement (IAP) = bladder pressure (mmHg) when the following criteria fulfilled:

• end of expiration
• supine
• zeroed at iliac crest in the mid-axillary line (WSACS recommendation; other sources suggest using the pubic symphysis)
• instillation of 25mL of saline into the bladder (1ml/kg for children up to 25 kg, minimum of 3 mL)
• measured  60 seconds after instillation to allow detrusor muscle relaxation
• in absence of active abdominal muscle contraction

Usually measured every 4 hours (more frequent if IAP >12mmHg or otherwise concerned)

COMPLICATIONS

• as for IDC
• falsely high readings from chronic or radiation cystitis or pelvic haematoma
• falsely low readings if there is a leak in the system

FURTHER INFORMATION

Definitions

• IAP is normally ~ 5–7 mmHg in critically ill adults
• intra-abdominal hypertension (IAH) is defined by a sustained or repeated pathological elevation in IAP ≥ 12 mmHg
• abdominal compartment syndrome (ACS) is defined as a sustained IAP > 20 mmHg (with or without an abdominal perfusion pressure (APP) < 60 mmHg) that is associated with new organ dysfunction/failure

Grades of IAH

• Grade I = IAP 12–15 mmHg
• Grade II = IAP 16–20 mmHg
• Grade III = IAP 21–25 mmHg
• Grade IV = IAP > 25 mmHg

References and Links

LITFL

• CCC — Abdominal Compartment Syndrome

Journal articles

• Kirkpatrick AW, 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 Jul;39(7):1190-206. PMC3680657.

FOAM and web resources

• World Society of the Abdominal Compartment Syndrome
• RCH Melbourne — Intra-abdominal Pressure Monitoring