Abdominal Compartment Syndrome: All About the Abdominal Crisis

Introduction

Abdominal compartment syndrome (ACS) is a medical emergency that occurs due to increased intra-abdominal pressure (above 20 mm Hg) in critically ill patients. Failure in early diagnosis and management has increased the rate of mortality and morbidity associated with ACS. ACS can lead to multiple organ dysfunction. A sustained intra-abdominal pressure(IAP) above 12 mm Hg results in Intra-abdominal Hypertension (IAH). ACS presents with a sustained IAP above 20 mm Hg and associated organ failure.

IAH (intra-abdominal hypertension) is classified as follows:

• Grade Ⅰ - 12 to 15 mm Hg.

• Grade Ⅱ - 16 to 20 mm Hg.

• Grade Ⅲ - 21 to 25 mm Hg.

• Grade Ⅳ - > 25 mm Hg.

In patients with grade Ⅳ Intra-Abdominal Hypertension(IAH), the incidence of organ failure is the highest. IAH, if not detected at an early stage or treatment is delayed, will progress to ACS. The heart, kidneys, and lungs are the organs that are mainly affected by ACS.

What Are the Different Types of ACS?

ACS is of three types- Primary, Secondary, and Recurrent.

Primary ACS:

Primary ACS is characterized by brief IAH duration and intraabdominal etiology (cause). It mainly occurs in postoperative surgical patients and traumatically injured patients. Primary ACS is associated with disease or injury in the abdominopelvic region. This condition requires early surgical or radiological intervention. The main causes include

• Ruptured abdominal aortic aneurysm (AAA).

• Abdominal blunt/trauma.

• Hemoperitoneum.

• Retroperitoneal haematoma.

• Acute pancreatitis.

• Liver transplantation.

Secondary ACS:

Secondary ACS is associated with extra-abdominal etiology that results in IAH. The main causes include:

• Major burns.

• Sepsis.

• Ascites.

• Capillary leak.

Recurrent ACS:

Recurrent ACS is characterized by the redevelopment of ACS symptoms after the resolution of earlier ACS episodes (either primary or secondary ACS). It represents a second-hit phenomenon.

Chronic cases of ACS are associated with certain conditions like pregnancy, obesity, cirrhosis, intraabdominal malignancy, peritoneal dialysis, etc.

What Is the Pathophysiology of Abdominal Compartment Syndrome?

ACS can affect the cardiovascular, gastrointestinal, renal, respiratory, and central nervous systems. The effects of ACS in these systems are:

Cardiovascular:

• Increased IAP and inferior vena cava compression result in reduced cardiac output.

• Reduced stroke volume.

• Hypotension.

• Increased systemic vascular resistance.

• Increased risk of venous thrombosis.

Renal:

• Reduced renal blood flow.

• Reduced urinary output.

• Reduced glomerular filtration rate (GFR).

Hepatic:

• Reduced portal blood flow.

• Jaundice.

• Increased serum liver enzymes.

Gastrointestinal:

• Reduced celiac blood flow.

• Reduced mucosal blood flow.

• Reduced perfusion to abdominal organs.

Central Nervous System:

• Increased intracranial pressure.

• Reduced cerebral perfusion pressure.

• Increased agitation.

• Changes in mental status.

Respiratory:

• Hypoxia.

• Increased intrathoracic pressure.

• Decrease tidal volume.

What Are the Signs and Symptoms of Abdominal Compartment Syndrome?

As ACS is an emergency condition with the critically ill being most affected, the patient is usually not in a position to communicate the symptoms. The usually reported symptoms are:

• Malaise.

• Lightheadedness.

• Dyspnoea.

• Abdominal pain.

On physical examination, the following findings are noted:

• Hypotension.

• Tachycardia.

• Oliguria.

• Abdominal tenderness.

• Tense and distended abdomen.

• Increased jugular venous pressure.

• Peripheral edema.

• Signs of hypoperfusion (like cold skin, restlessness, lactic acidosis, etc.).

• Cyanosis.

• Wheezing.

• Breathing difficulty.

What Diagnostic Tests Are Done for Abdominal Compartment Syndrome?

Diagnosis can be confirmed by intra-abdominal pressure (IAP) measurement. IAP is measured in two ways:

1. Direct Method: In the direct method, abdominal pressure is measured using a pressure transducer (eg. Using a Veress needle in laparoscopic surgery) or intraperitoneal catheter. The disadvantage of this method is that it is invasive, but the advantage is that it is highly accurate.

2. Indirect Method: The indirect method is commonly used for measuring IAP. This intravesicular catheter pressure technique is considered the gold standard for measuring IAP. The greatest advantage of this technique is its limited invasiveness and widespread availability. This technique uses a Foley catheter, and about 25 cubic capacity of sterile saline is injected into the bladder. This technique helps in measuring bladder pressure. A bladder pressure of less than 5 mm Hg is seen in healthy patients. A bladder pressure of 10 to 15 mm Hg is seen in obese patients and patients following abdominal surgery. A bladder pressure greater than 25 mm Hg is suspicious of ACS.

The trans bladder technique is contraindicated in cases of neurogenic bladder, pelvic hematoma, benign prostatic hypertrophy (BPH), and bladder trauma.

Other investigations done include:

• CT (computed tomography) and abdominal ultrasound reveal bowel thickening, a round abdomen, the collapse of the vena cava, and bilateral inguinal herniation.

• Oxygen saturation test to measure blood oxygen levels.

How Is Abdominal Compartment Syndrome Managed?

The most effective and primary treatment option is surgical decompression.

Nonsurgical therapeutic options aim at improving abdominal wall compliance and decreasing muscle contraction, surgical decompression, abdominal fluid drainage, and correction of positive fluid balance.

Non-surgical interventions are done to prevent IAH from progressing to ACS. NG tube placement is done for gastric decompression, renal tube placement for colonic decompression, and percutaneous drainage of abscesses, ascites, or for removing abdominal fluid. Neuromuscular blockade is used for abdominal musculature relaxation, which further decreases abdominal compartment pressure. If the condition does not resolve with conservative and medical management, then surgical decompression is done with emergency laparotomy. After emergent laparotomy, temporary abdominal fascia closure is done using devices (meshes, zippers, or vacs).

As multiorgan dysfunction occurs as a sequela of ACS, surgical abdominal decompression will improve the function of the affected organ systems. After surgical decompression, most patients require diuretics, fluid restriction, and deep venous thrombosis prophylaxis.

What Is the Prognosis of the Condition?

If untreated, ACS can lead to death. The mortality rate increases with a delay in treatment. Even after treatment, recovery is delayed due to multiorgan involvement.

In diabetic patients and those undergone major blood transfusions, the risk for mortality with ACS is higher. The mortality rate is directly proportional to abdominal pressure; the more pressure, the more the risk for death.

What Are the Complications?

The complications associated with ACS are

1. Renal failure.

2. Shock.

3. Bowel ischemia (reduced intestinal blood flow).

4. Respiratory distress (a life-threatening condition characterized by oxygen deficiency).

Conclusion

ACS is a rare but life-threatening medical emergency, which has been reported in all age groups, mostly in critically ill patients. ACS is associated with a high mortality rate due to failure in early diagnosis and delays in treatment. Early diagnosis and prompt treatment improve the prognosis of the condition.