[Measurement of the intra abdominal pressure in clinical practice]

In recent years, significant interest has been observed in intra-abdominal hypertension and abdominal compartment syndromes. Intra-abdominal pressure (IAP) has been defined as a static pressure between organs in the abdominal cavity. Continuous or recurrent increase in the IAP above 12 mm Hg (1.6 kPa) is regarded as abdominal hypertension (IAH). Among the most common causes of IAH are massive fluid resuscitation after major injuries or burns, and ischemia of intestines after major vascular surgery. Abdominal compartment syndrome has been defined as a continuous intra-abdominal pressure above 20 mm Hg (2.67 kPa) with coexisting organ dysfunction or failure. The mortality of patients with recognized abdominal compartment syndrome may be as high as 42%. Diagnosis of intra-abdominal hypertension is based on the measurement of IAP only. The World Society of the Abdominal Compartment Syndrome (WSACS) has been advising screenings of IAP in all patients admitted to intensive care units with certain risk factors. As a standard measurement of IAP, the pressure in the bladder filled maximally with 25 mL of sterile normal saline is accepted. IAP should be measured at the end-expiratory phase, in the flat supine position, after relaxation of abdominal muscles and referred to the median axillary line as a zero-level. In confirmed cases of IAH and/or ACS, immediate action should be taken. It consists of evacuation of gastric and bowel contents, maintenance of adequate blood pressure, diuretics and/or ultrafiltration, and ultimately deeper sedation and/or muscle relaxation. Surgical percutaneous evacuation of the fluid or a decompression laparotomy may be considered.