The abdomen is left open in specific circumstances: as part of a damage control strategy, planned second-look operations, and prevention of abdominal compartment syndrome. However, in the combat setting the open abdomen will be used much more liberally for several additional reasons. In general, combat injuries can be more severe, often multi-system, and resources and personnel may be limited. CT scans (“truth machines”) are not available in far-forward locations. Multiple fragment wounds or blast injuries have a higher potential for missed injuries or progression of injury that can be identified at a second-look operation. Limited time, limited supplies, and multiple casualties waiting for an operation will often mandate rapid temporary closure even in situations where you might otherwise perform a definitive closure. And don’t forget to consider the evacuation process – you cannot monitor your patients for missed injuries or the development of catastrophic abdominal complications or compartment syndrome if they are on a helicopter or airplane.

Damage control surgery is required for the seriously injured patient, when it is critical to get in and get out and avoid the lethal triad of metabolic acidosis, coagulopathy, and hypothermia. Rapid initial surgeries have specific goals: control of hemorrhage by ligating, repairing or shunting injured vessels, and/or packing of solid organ or pelvic injuries and control of contamination by identifying injuries to bowel and repairing, diverting, or stapling ends without any attempt at anastomosis. By accomplishing only what is absolutely necessary, the patient can be taken to the ICU to continue resuscitation and prepare the patient for more definitive operations when they are more stable. The abdomen is closed temporarily with dressings detailed below, but whipstitch skin closure only or penetrating towel clamps can also be used if that is all that is available.

Packing is an essential component of damage control if bleeding from solid organ or venous injury is present. The abdomen is packed, temporary closure is achieved, and the patient is stabilized prior to further treatment of the injuries. Packing must provide enough pressure to tamponade bleeding, but care must be taken to not compress the inferior vena cava and decrease venous return to the heart. Hypovolemia is often present in this scenario, exacerbating the problem. If a patient cannot be stabilized after packing, reassess the packing and temporary closure. Although time is a critical factor in these patients, do not just assume that a panicked abdominal packing is an adequate damage control procedure. An extra 10 or 20 min in the OR to assure that you have adequate hemorrhage and contamination control is much preferred to watching your patient bleed out from their abdominal wound in the ICU. Abdominal compartment syndrome is still possible with vacuum closures and other temporary closures and may prompt an early return to the operating room or a bedside laparotomy in the ICU.

The abdomen should always be left open if a second look is planned. This is especially useful if the second look will be done by another surgeon at a higher level of care. Clearly dead bowel should be resected; however, it is not always obvious if bowel cannot be saved. If there is a question of bowel viability at the initial surgery, an extensive resection of potentially viable bowel should be avoided and a second look should be planned. Bowel viability may improve with continued resuscitation, and prevention of extensive resection is necessary to avoid short gut syndrome. Anastomoses in a patient with potential for deterioration are risky and so are often better served by delay until a subsequent return to the OR. An ostomy could be avoided if the patient remains stable after the initial operation, and an ostomy can be formed at the second look if the situation for an anastomosis is not ideal. A failed anastomosis that is not immediately recognized can lead to overwhelming sepsis requiring significant fluid resuscitation and virtually guarantee an open abdomen that is difficult to close.

It is critical to identify abdominal compartment syndrome (ACS) and predict patients who may develop this syndrome. Unfortunately, we have no absolute measures for predicting which casualties will go on to develop ACS. Patients that are already acidotic, hypothermic, and coagulopathic are at the highest risk for ACS and should be left open. Other high risk factors are patients receiving massive transfusion or large volume resuscitation, large thermal injuries, high grade liver injuries, and mesenteric vascular injuries. The abdominal domain is limited, and excessive visceral or retroperitoneal edema, blood, gas, ascites, or stool can cause systemic life-threatening problems. Abdominal compartment syndrome can occur in patients without intra-abdominal injuries (secondary ACS) in cases of substantial bowel or retroperitoneal edema from massive fluid resuscitations or systemic inflammatory responses with capillary leak causing extensive interstitial edema. Clinical signs of ACS include a tight and distended abdomen, hypotension, low urine output, and rising ventilatory peak pressures. This clinical picture should prompt immediate opening or reopening of the abdominal cavity. One exception to this rule is the patient who has a purely secondary ACS , which is usually due to massive volume resuscitation and the buildup of tense abdominal ascites, most commonly seen in injured patients with significant burns. Emergent laparotomy in a significant burn patient has a tremendously high mortality rate. Attempting all other methods of decreasing abdominal pressure is best. A quick bedside ultrasound or diagnostic tap can identify the presence of massive ascites, and these patients may be better managed by large volume paracentesis or placement of a percutaneous drain. Improving ventilation, decreasing fluid overload, improving sedation, and nasogastric or orogastric decompression can help mitigate an elevated abdominal pressure.

Measurements of intra-abdominal pressure are useful for identifying impending or active ACS and are usually achieved by indirect methods. Bladder pressure is most commonly used (Fig. 12.1): the bladder is decompressed with a Foley catheter, 50–200 cc of sterile saline is infused into the catheter, and the catheter is then clamped distal to the area of pressure measurement. A pressure transducer with a needle (like that used for arterial pressure measurements) is used to puncture the hub of the Foley as shown in Fig. 12.1. The transducer should be zeroed at the symphysis pubis with the patient in a supine position and then allow the waveform time to equilibrate. Although bladder pressure is most commonly used, you can measure intra-abdominal pressure via any hollow structure in the abdominal cavity. Alternative methods of indirect measurements include intragastric (NG tube) or inferior vena cava pressure through the femoral vein. If pressure-transducing equipment is not available, see Appendix A for a low-tech bedside method of estimating bladder pressure.

Although every patient may respond differently, organ dysfunction increases with increasing intra-abdominal pressure (IAP), and a value of >25 mmHg has been suggested as a target for decompression. Reopening and re-exploration is recommended for anyone with a pressure above 35 mmHg. One pitfall you have to take into consideration is that these pressure cutoffs generally apply to normotensive patients. Abdominal compartment syndrome can occur with bladder pressures of less than 20 in patients with hypotension! Think of the abdominal cavity like the cranial vault – the perfusion pressure will be a function of the mean arterial pressure (MAP) minus the abdominal compartment pressure. Therefore, if the MAP is already low, then even an abdominal pressure of 15 mmHg can result in a perfusion pressure that is inadequate. Remember that abdominal compartment syndrome is a clinical diagnosis  – no single test is absolutely necessary for the diagnosis and treatment of ACS. A patient with a tight abdomen and who is difficult to ventilate should have consideration given to opening the abdomen. When in doubt, open a closed abdomen or leave the abdomen open.

Intra-abdominal contents must be protected from desiccation and from insensible losses. Temporary closures have been used to achieve this goal, and many different types of closure have been described. The most common method of temporary closure involves using any type of plastic occlusive barrier such as large sterile irrigation bags or Steri-Drape® (3 M®, St. Paul, MN) plastic sheeting with small slits cut in the plastic to allow egress of fluid. A sterile X-ray cassette cover will also work very well – use a scalpel to make multiple small slits in the plastic to allow fluid to flow into the vacuum component. This sheeting is then tucked under the fascia down to the paracolic gutters (Fig. 12.2), ensuring that all exposed bowel is covered and protected from direct contact with any sponge material. Laparotomy sponges or operative towels are then placed over the plastic barrier, with drains within or on top of the sponges. An occlusive dressing like Ioban® (3 M®, St. Paul, MN) is then used to seal the wound. Fluid egress is achieved with large tubes (often nasogastric tubes with the air vent portion of the sump drain tied into a knot, chest tubes, or 2 JP drains) placed on top of the towels or gauze and underneath the occlusive dressing with attachment to continuous wall suction. It is important to create a “mesentery” with the Ioban® around the tube used to prevent leaks and pressure on the skin (Fig. 12.3a, b). Adaptors are needed to attach the closure to suction, and it is important to identify which adaptors will be needed ahead of time.