The evaluation and management of critically ill patients requires assessing multiple pieces of clinical, laboratory and physiologic information. Since intra-abdominal hypertension causes severe physiologic alterations as well as misleading data such as CVP and pulmonary arterial occlusion pressure, it is important for the clinician to know the patients intra-abdominal pressure to be able to assess the entire clinical scenario. In addition, unlike many conditions where supportive care is all that is possible, interventions exist to treat elevated intra-abdominal pressure. For these reasons, all patients at risk of developing IAH should have intra-abdominal pressure measured, trended and recorded.

Rising intra-abdominal pressure is a clinically silent process that is not apparent until the disease is well progressed.[1, 2] Detecting intra-abdominal hypertension early requires a high index of suspicion, recognition of early symptoms and a consistently applied method to measure intra-abdominal pressure. Unfortunately, clinical exam is notoriously inaccurate.[1, 2] Kirkpatrick et al conducted a study comparing measured intra-abdominal pressures to physician clinical exam.[1] They found that clinical judgment failed to detect significant intra-abdominal hypertension over 40% of the time. Sugrue, et al found similar results.[2] Both authors conclude that clinical exam is unreliable and recommend routine intra-abdominal pressure monitoring.

Since clinical exam is inaccurate, early detection of increasing intra-abdominal pressure requires a reliable, reproducible method of measuring it. In addition, the method should be simple enough that the nursing staff is willing to take frequent measurements to allow early detection of rising IAP. Since recent literature notes that patients develop ACS in as little as 6 to 8 hours, it is probably reasonable to suggest initial measurements be taken at least every 1 to 2 hours until a clear trend is established (See IAP monitoring algorithm).[3] To date, the most reliable method is via pressure transduction through a catheter within the peritoneal cavity. Other less invasive options include pressure transduction through a tube placed in the stomach, bladder, or rectum.[1, 2] Of these options, Obeid et al found bladder pressure to most closely reflect intraperitoneal pressure and to be the most technically reliable.[4] Other authors confirm Obeid’s findings.[5] Bladder pressures taken through a Foley catheter correlate very closely with pressures measured directly in the abdominal cavity and are becoming the primary method of monitoring intra-abdominal pressure.

1. Kirkpatrick, A.W., et al., Is clinical examination an accurate indicator of raised intra-abdominal pressure in critically injured patients? Can J Surg, 2000. 43(3): p. 207-11.
2. Sugrue, M., et al., Clinical examination is an inaccurate predictor of intraabdominal pressure. World J Surg, 2002. 26(12): p. 1428-31.
3. Balogh, Z. and F.A. Moore, Recent advance in the characterisation of post-injury abdominal compartment syndrome. International J Intensive Care, 2004. 11(1): p. 30-42.
4. Obeid, F., et al., Increases in intra-abdominal pressure affect pulmonary compliance. Arch Surg, 1995. 130(5): p. 544-7; discussion 547-8.
5. Iberti, T.J., C.E. Lieber, and E. Benjamin, Determination of intra-abdominal pressure using a transurethral bladder catheter: clinical validation of the technique. Anesthesiology, 1989. 70(1): p. 47-50.