Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (86 page)

Damage control laparotomy (DCL) is a concept that has expanded from its initial role in trauma surgery (see also
Chapter 13
). Trauma patients become hypothermic, acidotic and coagulopathic, and surgery becomes unsurvivable. Rapid, immediately life-saving surgery (‘staple, pack and go’) is carried out and the patient returned to ICU for warming and resuscitation, with more definitive surgery deferred for 24–48 hours once coagulopathy has been corrected and homeostasis returned towards normal. In abdominal sepsis it holds true that the first laparotomy carries the best chance for salvage.
²⁸
However, in severely unstable patients it can be better to make an active decision to quickly drain pus, remove dead tissue, stop bleeding by packing and close overtly leaking bowel with staples (without resection) before terminating the operation. Indications for this include haemodynamic instability, massive haemorrhage, coagulopathy, abdominal compartment syndrome and acute mesenteric ischaemia.
³²
Packs should generally be removed as early as possible once clotting is restored and usually the next day. The small bowel becomes adherent remarkably quickly and can be damaged as packs are removed. Packs should be removed cautiously under direct vision with saline irrigation and gentle finger separation.

This term refers to the planned re-exploration of the abdomen, planned at the previous procedure in order to re-operate before any clinical deterioration occurs. The term distinguishes it from ‘laparotomy on demand’, which is now the more common approach and where the abdomen is only explored when a new problem is diagnosed. After DCL, a second look is obviously required to complete the necessary definitive procedures, but the term is more commonly applied to ‘looking again’ after laparotomy for intestinal ischaemia. The extent of intestinal ischaemia may not be fully evident at the first operation and, particularly if the bowel has been re-anastomosed, looking again at 48–72 hours, depending on progress, can identify further ischaemia before the patient deteriorates. In some cases of intestinal ischaemia where there may be doubt as to the extent, it may be preferable to resect and staple off the bowel ends, forcing the surgeon to re-explore 48 hours or so later, rather than gamble on anastomosing bowel that might be subclinically ischaemic and subsequently break down at a later date.

Repeated planned re-laparotomies have been used aggressively for abdominal sepsis with MOF in both Europe and North America for some years. In this method of treatment, the abdomen is typically re-operated upon every 24–48 hours for several days to wash out the peritoneal cavity and remove any ongoing sepsis. However, a recent randomised trial has shown that this approach is associated with significantly more laparotomies and prolonged ICU stay compared to a ‘re-laparotomy on demand’ approach.
³³
Although on occasions there may be a case for a single planned second-look laparotomy in patients with severe faecal peritonitis, even this is debatable. This should not, however, divert the surgeon from maintaining a low threshold for early laparotomy on demand when indicated, as delaying necessary surgery worsens outcome.
²⁸

In adverse circumstances, the abdomen is occasionally left open as a last resort in allowing pus and enteric contents to drain. More often it is left open in preference to closing it with undue tension. Abdominal compartment syndrome (see below) may also lead to an open abdomen. Leaving the abdomen open in appropriate circumstances can avoid or reduce septic, enteric and wound complications. It also allows improved systemic function, faster weaning from the ventilator and can facilitate early enteral nutrition. However, it is deforming, increases evaporative losses, and exposes the bowel to risk of damage and fistulation. The open abdomen is particularly challenging to nurse, and comfortable, secure, wound care may be difficult to achieve.
³⁴
Prolonged healing is usually required with a risk of late herniation. These deleterious effects are significant enough to make one caution against unnecessary use of laparostomy.
¹⁹
It is undoubtedly a valuable and life-saving technique when needed but it is also a significant future burden to the patient in its own right.

In closing the abdomen during laparotomy for abdominal sepsis, the surgeon should close the fascia conventionally but avoid tension. Tension sutures have little to recommend them and their continued use is not supported. If bowel distension, oedema, haemorrhage (or packing) combine to make closure impossible, then there are several options open to the surgeon, depending on a number of factors, including the likely time course of recovery. In general, each end of the wound is closed conventionally to the point of reasonable tension and the central defect left open. For short-lived oedema (e.g. after aortic aneurysm repair or traumatic haemorrhage) the defect can be covered with abdominal packing, which is changed daily until such time as the defect can be closed or a longer-term solution implemented (see below). Early dressing changes should be carried out by the surgical team. The small bowel will become adherent to any gauze dressings, and gentle separation will be required to avoid injury.

A double-sandwich dressing of semipermeable adhesive dressing with moist gauze between the layers of dressing protects the bowel with less adhesion formation than with standard gauze packs. There are various commercial plastic sheets that can be used. Alternatively, a version of the Bogota bag can be used (
Fig. 18.3
). In this technique, a sterile 3-litre intravenous fluid bag is slit open and sutured to the fascia, covering and protecting the bowel and providing it with a clean, moist environment. Again, as the oedema subsides, usually within 72 hours or so, the Bogota bag or double-sandwich dressing can be removed and the abdomen either closed or a longer-term technique instituted.

In recurrent sepsis, where recovery is likely to be slow, prosthetic mesh can be used to restrain the viscera. In abdominal sepsis, absorbable polyglactin meshes are preferred to non-absorbable polypropylene meshes, as there is less likelihood of chronic mesh infection and fistulation to underlying bowel.
³⁵
Caution is also required in the use of bioprosthetic collagen meshes on account of complications and cost.
³⁵

Whichever technique is employed to close the abdomen, the later development of an incisional hernia is almost inevitable, but might be less so with the non-absorbable mesh. If the contamination is particularly severe such that a further laparotomy and lavage is planned in 24–48 hours, then mesh placement can be deferred until then. Likewise if oozing requires gauze packing then mesh placement can be effected when the gauze is removed. The mesh and bowels must still be kept moist and protected, and a double-sandwich dressing achieves this admirably. If there is a lot of effluent or tissue fluid, then use of low-grade suction can help provide control. As the wound shrinks, these bulky dressings can be changed to a large fistula bag, even if there is no fistula, as again it provides a non-adherent moist environment.

Use of commercial vacuum dressings has become widespread as they make wound management considerably easier, and provide a ready-made technique for the non-expert unit. Early cohort studies suggested that vacuum-assisted closure was well tolerated in the open abdomen, with intestinal fistulation rates of 5%.
³⁶
However, these findings have not been borne out by the only randomised trial on vacuum-assisted closure in the open abdomen, which compared it to polyglactin absorbable mesh. Whilst not statistically significant, the rate of fistulation in the vacuum-assisted closure arm was 21%.
³⁷
Controversy regarding the rate of intestinal fistulation continues,
^34
,
38
while the results of a national audit coordinated by the National Instititute of Health and Clinical Excellence (NICE) are awaited. Until the intestinal fistulation rate has been clarified, particular caution is required on the use of vacuum dressings in the presence of suture or staple lines, repaired serosal tears or enterotomies.

Normally, intra-abdominal pressure is low (< 10 mmHg), but it is increasingly recognised that it can be raised in abdominal sepsis (and other acute abdominal conditions, including trauma and pancreatitis) to the significant detriment of the patient. The condition is recognised with increasing frequency and is probably not as uncommon in our practice as previously thought.
³⁹
As abdominal pressure rises, venous return is impaired and with it cardiac output. The tense abdomen can cause pulmonary compromise, oliguria, mesenteric ischaemia and even raised intracranial pressure. These features constitute the abdominal compartment syndrome (ACS) – similar in some ways to a tension pneumothorax, within the abdomen.
⁴⁰

ACS is caused by multiple factors that exist after certain operations, typically those for peritonitis, abdominal aneurysm and abdominal trauma. Tissue oedema results from the combined effects of tissue injury, intravenous fluid infusion and leaky capillaries, while bowel distension and haematomas also contribute. ACS is seen most commonly after fascial closure but it can also occur in the abdomen that has been left open and packed, especially if there is ongoing haemorrhage. Operations likely to cause ACS include those involving significant haemorrhage, retroperitoneal or intestinal oedema, bowel distension, aortic clamping, hypothermia, massive transfusion or prolonged surgery. These circumstances should heighten the surgeon's awareness of ACS as a potential complication. ACS is not restricted to emergency surgery and prolonged elective surgery with a scarred and rigid abdominal wall may also lead to this condition. The anaesthetist may signal an unacceptable rise in the ventilatory pressure as the abdomen is closed but more commonly ACS develops on the critical care unit, some 12–30 hours after surgery. Oligo/anuria and raised ventilatory pressures are the usual presenting features.

Intra-abdominal pressure (IAP) is measured via the bladder following instillation of 25 mL of normal saline. The IAP is measured through the aspiration port of the catheter tubing using a transducer. The transducer should be zeroed at the level of the mid axillary line, and IAP measured in the supine position at end expiration.
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Standardised definitions for ACS were developed in 2006 by an international consensus group
⁴¹
(
Box 18.8
).

In intra-abdominal hypertension (IAH) and ACS, a number of medical treatment options are of benefit in reducing IAP.
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Abdominal wall compliance can be improved with adequate sedation, analgesia and neuromuscular blockade. Intraluminal contents should be evacuated with nasogastric and rectal decompression and the use of prokinetic agents. Abdominal fluid collections should be aspirated. Positive fluid balance can be corrected with fluid restriction, diuretics or dialysis/ultrafiltration. However, if pressures above 20 mmHg persist despite these measures, or organ dysfunction worsens, then the abdomen will need to be decompressed and left open using the techniques discussed above.