Abdominal Compartment Syndrome

Question 1

You are asked to review a 64-year-old male patient who was admitted to the intensive care unit 1 day ago following an emergency laparotomy for excision of ischaemic bowel. He has a BMI of 42 and has a history of hypertension. He remains intubated and ventilated, is oliguric, and is now demonstrating worsening acidosis on his arterial blood gas.

What are the potential causes of deterioration in this patient?

Answer 1

• Sepsis.
• Fluid imbalance/hypovolaemia.
• Low cardiac output state/hypotension.
• Acute kidney injury.
• Electrolyte/metabolic disturbance.
• Raised intra-abdominal pressure.

Question 2

What is abdominal compartment syndrome?

Answer 2

• A sustained increased in intra-abdominal pressure above 20mmHg, with consequent signs and symptoms of organ dysfunction.

Normal intra-abdominal pressure is ~5mmHg, and intra-abdominal hypertension is defined as a pressure above 12 mmHg.

Question 3

What are the risk factors for the development of abdominal compartment syndrome?

Answer 3

Poor abdominal wall compliance:

• Lung pathologies causing increased thoracic pressure.
• Major abdominal surgery.
• Prone positioning.

Increased abdominal content:

• Ileus.
• Severe ascites.
• Pneumoperitoneum (iatrogenic/pathological).
• Pancreatitis (due to local complications e.g. pseudocyst formation or
  indirectly secondary to fluid resuscitation/ileus).
• Intra-abdominal bleeding (AAA, trauma,
  retroperitoneal haematoma).

Question 4

What are the risk factors for the development of abdominal compartment syndrome?

Continued…

Answer 4

Fluid and electrolyte imbalance:

• Burns.
• Trauma.
• Metabolic disturbances.
• Persistent hypotension.
• Hypothermia.
• Massive transfusion.
• Deranged clotting.
• Severe sepsis/shock.

Patient factors:
* Age.
* Raised BMI (particularly central obesity pattern).

Question 5

How can this patient’s intra-abdominal pressure be measured?

Answer 5

Intra-vesical measurement:

• Ensure the patient is catheterised and supine. Drain the catheter fully and clamp.
• Connect the patient’s catheter to a 3-way tap and a pressure transducer (zeroed).
• Inject 20–25mL of 0.9% sodium chloride into the bladder and measure the pressure at the end of expiration.

Question 6

The patient’s intra-abdominal pressure consistently measures above 25 mmHg.

What are the potential systemic complications?

Answer 6

• Decreased cardiac output, venous return and contractility through cardiac compression.
• A further drop in abdominal perfusion pressure, causing:
• Ischaemic bowel.
• Acute liver injury.
• Difficulty ventilating due to poor pulmonary compliance and increased thoracic pressure.
• Acute kidney injury secondary to poor perfusion and obstruction of the venous supply and ureters.
• Increased length of intubation/ventilation and stay on intensive care, with its associated risks.
• Overall increase in morbidity and mortality.

Question 7

How would you manage this patient?

Answer 7

Assessment:
* ABCDE assessment focusing on the risk factors/causes of raised intra-abdominal pressure.
* Serial monitoring of intra-abdominal pressure.
* Cardiac output assessment/monitoring to optimise fluid resuscitation
and the use of vasoactive substances.
* Consider the need for diagnostic imaging.

Treatment
* Largely supportive, ensuring optimal positioning (reverse Trendelenburg), ventilation, feeding and fluid balance of patient.
* Consider nasogastric and flatus tubes to decompress if appropriate.
* Ensure adequate sedation and paralysis to prevent increases in
pressure due to ventilator dysynchrony or coughing.
* Adjust the cardiovascular physiology to optimise abdominal
perfusion pressure and fow.
* Consider renal replacement therapy if indicated.
* Multidisciplinary discussion with the surgical team to assess the
risks and benefits of a decompression laparostomy, which should be considered in patients with intraperitoneal fuid, abscess or blood.