Intra-abdominal hypertension (defined as a sustained urinary bladder pressure > 12 mm Hg) may be an under-recognized problem in the ICU, especially in patients after abdominal surgery or who have gone massive volume resuscitation with blood and/or fluids (think hemorrhage, burns and sepsis). When high abdominal pressures ( > 20 mm Hg sustained) cause organ failure and/or shock, it's called  abdominal compartment syndrome.