Abdominal contents are primarily fluid in character so that pressure within this compartment follows Pascal’s hydrostatic law. Intra-abdominal pressure (IAP) is the steady state pressure within the abdominal cavity and changes during respiration with an inspiratory increase. Mean perfusion pressure (MPP) is the difference between mean arterial pressure (MAP) and central venous pressure (CVP).

Similarly abdominal perfusion pressure (APP) is calculated as the difference between MAP and IAP. MPP has been seen to be associated with progression of organ system injury.

Continuous intra-abdominal pressure has many possibilities:

First, an IAP trend allows to assess the effect of treatment, to visualize the interaction between physiologic variables in real time.

Second, CIAP allows the user to obtain a continuous APP trend as a potential better resuscitation target and for early identification of impending ACS.

Third, CIAP allows automation via computer analysis and calculation of the area under the curve (AUC) and the time above a threshold as in analogy to ICP where the pressure time-burden may be of prognostic value.

Fourth, CIAP allows to diagnose poly-compartment syndrome and prediction of acute kidney injury (AKI) and cardio-abdominal-renal syndrome (CARS) earlier than via the intermittent measurement technique.

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