Abdominal Compartment Syndrome

Massive intestinal oedema often follows laparotomy for major tra uma where there has been prolonged shock. Crystalloid resuscitation, capillary leakage due to activated inflammatory mediators and reperfusion injury all contribute to this tissue swelling. Combined with intra-abdominal packing or retroperitoneal haematomas this may render the abdomen difficult or impossible to close. If the abdomen is closed, intra-abdominal pressure may rise to a level (>25 cmH2O) where it leads to significant cardiovascular, respiratory, renal and cerebral dysfunction.

Damage Control Surgery

Overview
Metabolic failure
Damage control laparotomy
Organ-specific techniques
Critical Care
Abdominal Compartment Syndrome
Reoperation

Cardiovascular
A rise in the intra-abdominal pressure leads to a fall in cardiac output, due mainly to compression of the inferior vena cava and reduction in venous return to the heart. Cardiac output is reduced despite apparent rises in central venous pressure, pulmonary artery occlusion pressure and systemic vascular resistance. This distortion of standard monitoring modalities makes adequate and appropriate resuscitation difficult.

Respiratory
Raised intra-abdominal pressure will effectively splint the diaphragm and lead to a rise in peak airway pressure and intra-thoracic pressure and subsequently a reduced venous return to the heart. The increase in airway pressures may also exacerbate barotrauma and contribute to the development of acute respiratory distress syndrome.

Renal
An acute increase in intra-abdominal pressure leads to oliguria and anuria probably due to compression of the renal vein and renal parenchyma. Renal blood flow, glomerular filtration are decreased with a corresponding increase in renal vascular resistance.

Cerebral
The rise in intra-abdominal pressure, intrathoracic pressure leads to a rise in central venous pressure which prevents adequate venous drainage from the brain, leading to a rise in intracranial pressure and worsening of intracerebral oedema.

Diagnosis of Abdominal Compartment Syndrome
The abdominal compartment should be suspected and sought for in any multiple trauma patient who has undergone a period of profound shock. Clinically it is characterized by a fall in urine output associated with an elevated central venous pressure. The diagnosis can be confirmed by the measurement of intra-abdominal pressure. This may be done either through a foley catheter in the bladder or a nasogastric tube in the stomach. Simple water-column manometry is used at 2 to 4 hourly intervals, although it is possible to connect a pressure transducer to a foley catheter.

Normal intra-abdominal pressure is zero or subatmospheric. A pressure of over 25cmH2O is suggestive, and over 30cmH2O diagnostic, of the abdominal compartment syndrome.

Management
It is better to anticipate the development of abdominal compartment syndrome and use an alternate wound closure technique to prevent its occurrence. If the abdomen is at all difficult to close, this procedure should be abandoned at alternative techniques applied. A good rule of thumb is that if, when looking at the abdomen horizontally, the guts can be seen above the level of the wound, the abdomen should be left open and temporary closure utilized.

The easiest method to control the open abdomen is to use a silo-bag closure. A 3 litre plastic irrigation bag is emptied and cut open so it lies flat. The edges are trimmed and sutured to the skin, away from the skin edges, using a continuous 1 silk suture. It is useful to place a sterile absorbent drape inside the abdomen to soak up some of the fluid and ease control of the laparostomy.

An alternative technique is the 'vacuum-pack' technique. Here the 3 litre bag is opened and placed into the abdomen to protect the gut contents, under the sheath. Two large calibre suction drains are placed over this, and a large adherent steridrape placed over the whole abdomen. The suction catheters are connected to high-displacement suction to provide control of fluid losses and create the 'vacuum-pack' effect.

Do not suture material to the sheath. Repeated suturing of the sheath damages it and makes definitive closure impossible. If the sheath cannot be closed at a subsequent operation, the defect may be closed with an absorbable mesh system.

Sudden release of the abdominal compartment syndrome may lead to an ischaemia-reperfusion injury causing acidosis, vasodilatation, cardiac dysfunction and arrest. Prior to release the patient should be pre-loaded with crystalloid solution. Mannitol and vasodilators such as dobutamine or the phosphodiesterase inhibitors may have a place here.

Reoperation