Abdominal Compartment Syndrome

What are factors posing a risk for abdominal compartment syndrome?

Major trauma; damage control
Extensive burns
Large volume fluid resuscitation
Bowel distension from ileus, obstruction, or third spacing
Closure of abdomen under tension
Ischemia-reperfusion injury
Coagulopathy

What is abdominal compartment syndrome?

Intra-abdominal hypertension associated with end-organ dysfunction.

What are the three clinical findings associated with abdominal compartment syndrome?

1. Hypotension
2. Oliguria
3. Elevated peak airway pressures

What is the pathophysiology of abdominal compartment syndrome?

-Intra-abdominal hypertension decreases venous return and stroke volume, while increasing afterload, leading to a decrease in cardiac output.
-Decreased renal blood flow and GFR stimulates the renin-angiotensin-aldosterone system. However, direct renal vascular compression may lead to oliguria not responsive to volume.
-The diaphragm is displaced, decreasing TLC and FRC and increasing inspiratory pressures.
-Mesenteric flow decreases leading to splanchnic venous congestion, bowel mucosal edema, and acidosis.

What is intra-abdominal hypertension?

Intra-abdominal pressures greater than 10 mmHg

In the setting of intra-abdominal hypertension, what happens to CVP and PCWP readings?

Both appear elevated, even though the patient may have intravascular volume depletion.

What is a grading system used for intra-abdominal hypertension?

Grade I 10-15 mmHg - Maintain euvolemia
Grade II 15-25 mmHg - Volume expansion, may need surgery
Grade III 25-35 mmHg - Consider abdominal decompression
Grade IV >35 mmHg - Needs abdominal decompression with re-exploration

Signs of abdominal compartment syndrome usually do not manifest until Grade II intra-abdominal hypertension (greater than 15 mmHg or 20 cmH2O).

How do you measure abdominal pressures?

The most common surrogate is the measurement of bladder pressures.
1. Inject 50mL NS into the aspiration port of a Foley catheter.
2. Place an occlusive clamp distally, or use a 3-way stopcock.
3. Insert a needle into aspiration port and connect to a CVP manometer.
4. Zero the manometer at the pubic symphisis.

Note that different publications report their units in cmH2O (direct measurement of height of column of water) or mmHg (what most CVP manometers will read). The conversion factor is 1 mmHg = 1.36 cmH2O.

What are two independent predictors for the development of abdominal compartment syndrome in non-trauma surgical patients?

1. Elevated peak airway pressures
2. Positive 24-hr fluid balance

When is abdominal decompression generally recommended?

1. IAP greater than 20mmHg with UOP less than 0.5ml/kg/h, peak airway pressure greater than 45 cmH2O, and DO2 less than 600ml/min/m2.
2. IAP greater than 25mmHg.

There are no hard and fast rules here, but avoid signs of organ dysfunction!

What are outcomes of abdominal decompression?

80% of patients have improvement in organ function.
Overall there is a mean survival rate of 53% (reports of 17-75%)!

Are there methods to prevent abdominal compartment syndrome?

Avoid primary fascial closure after damage control laparotomy or if the patient is at high risk at the time of the index operation.
-Temporary towel clip closure
-Prosthetic mesh closure
-Vacuum-assisted closure device

What are some methods of dealing with an open abdomen after decompressive laparotomy?

1. Bogota bag - suture sterile irrigation bag to the skin to protect abdominal viscera
2. Pack abdomen with saline gauze then cover with Ioban, with or without sump drains
3. Prosthetic mesh closures (some have built-in zippers or velcro)
4. Vacuum-assisted closure devices

Protect the fascia if possible so it can be saved for definitive closure!

Late... SG

Sources:
Schwartz' Principles of Surgery, 8th ed.
Moore AFK, Hargest R, Martin M, Delicata RJ. Intra-abdominal hypertension and the abdominal compartment syndrome. Br J Surg 2004; 91: 1102-1110.