Sindrome compartimental abdominal (SAC)

1. Intra-abdominal pressure (IAP) is the pressure concealed within the abdominal cavity. IAP varies with respiration. The normal adult IAP is around 5mmHg, but can be non-pathologically increased in the obese. Elevated IAP is a common finding among critically ill medical and surgical patients.

2. IAP should be expressed in mmHg (1 mmHg = 1.36 cm H2O) and measured at end-expiration in the complete supine position after ensuring that abdominal muscle contractions are absent and with the transducer zeroed at the level of the mid-axillary line.

3. The current reference standard IAP measurement method is the pressure measured via an indwelling urinary drainage catheter within the bladder.

4. The recommended standard technique for measuring IAP is as follows: 1) connect the culture aspiration port of the urinary tubing to a transducer; 2) clamp the tubing distal to the aspiration port; 3) instil a maximal volume of  25 ml of sterile room temperature saline into the bladder with the patient in the complete supine position; 4) zero the transducer at the mid-axillary line; 5) after a stabilisation period of at least 30-60 seconds,mean IAP is read either on the bedside monitor or as the height of the urine column in the drainage tubing.

5. APP= MAP– IAP > 60 mmHg Abdominal perfusion pressure (APP) assesses not only the severity of IAP, but also the adequacy of the patient’s systemic perfusion. APP = mean arterial pressure (MAP) – IAP.

6. Intra-abdominal hypertension (IAH) is the pathologic elevation of IAP. IAH is defined by a sustained or repeated IAP > 12 mmHg or an APP < 60 mmHg.

7. IAH may be graded as follows:




12-15 mm Hg


maintain normovolemia

16-20 mm Hg


hypervolemic resuscitation

21-25 mm Hg



> 25 mm Hg


decompression and re-exploration

8. According to the duration of symptoms, IAH may also be classified into two types:

9. Abdominal Compartment Syndrome (ACS) is present when organ dysfunction occurs as a result of IAH. ACS is defined by a sustained or repeated IAP > 20 mmHg and/or APP < 60 mmHg in association with new-onset single or multiple organ system failure. In contrast to IAH, ACS is not be graded, but rather considered as an “all or nothing” phenomenon.

10. ACS may be further classified into three types:


Etiologic factors for IAH
• Acidosis (pH below 7.2)
• Hypothermia (core temperature below 33°C)
• Polytransfusion (> 10 units of packed red cells / 24 hours)
• Coagulopathy (platelet count below 55000/mm3 OR anactivated partial thromboplastin time (APTT) more than 2times normal OR a prothrombin time (PTT) below 50% ORan international standardised ratio (INR) more than 1.5)
• Sepsis (as defined by the American - EuropeanConsensus Conference definitions)
• Bacteraemia
• Liver dysfunction with ascites
• Mechanical ventilation
• Use of positive end expiratory pressure(PEEP) or the presence of auto-PEEP
• Pneumonia
• Abdominal surgery, especially with tight abdominal closures
• Massive fluid resuscitation (> 5 liters ofcolloid or crystalloid / 24 hours)
• Gastroparesis / gastric distention / Ileus
• Haemoperitoneum
• Pneumoperitoneum