How is intraabdominal pressure monitored?
Intraabdominal pressure can be measured by transducing the pressure in the urinary bladder via a Foley catheter.
Twenty to 50 mL saline solution is instilled into the urinary bladder to ensure a continuous column of fluid. A needle (connected to a pressure transducer) is aseptically placed into the sampling port of the drainage tubing, which is clamped downstream from the port. The pubic symphysis is used as a zero reference. Alternatively, the drainage tubing itself can be used as a manometer.
Because urinary specific gravity is approximately 1, the height of the fluid column in centimeters needs to be multiplied by 0.74 to convert to millimeters of mercury.
Respiratory variation should be observed in the measured pressure to confirm that pressure is being transduced in the abdomen.
A sustained Intraabdominal pressure above 20 mm Hg with end-organ dysfunction (renal dysfunction, ventilator failure, or intestinal ischemia) is defined as 'Abdominal Compartment Syndrome.'