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 .