The role of source control in abdominal sepsis

Abdominal sepsis represents the host’s systemic inflammatory response to bacterial or yeast peritonitis.

In the event of peritonitis Gram-negative, gram-positive, as well as anaerobic bacteria, including common gut flora, such as Escherichia coli, Klebsiella pneumoniae, Streptococcus spp. and Bacteroides fragilis, enter the peritoneal cavity. Sepsis from an abdominal origin is initiated by the outer membrane component of gram-negative organisms (e.g., lipopolysaccharide [LPS], lipid A, endotoxin) or Gram-positive organisms (e.g., lipoteichoic acid, peptidoglycan), as well anaerobe toxins. This lead to the release of proinflammatory cytokines such as tumor necrosis factor α (TNF-α), and interleukins 1 and 6 (IL-1, IL-6). TNF-α and interleukins lead to the production of toxic mediators, including prostaglandins, leukotrienes, platelet-activating factor, and phospholipase A2, that damage the endothelial lining, leading to increased capillary leakage. Cytokines lead to the production of adhesion molecules on endothelial cells and neutrophils. Neutrophil-endothelial cell interaction leads to further endothelial injury through the release of neutrophil components. Activated neutrophils release nitric oxide, a potent vasodilator that leads to septic shock. Cytokines also disrupt natural modulators of coagulation and inflammation, activated protein C (APC) and antithrombin. As a result, multiple organ failure may occur.

The timing and adequacy of source control are of outmost importance in the management of intra-abdominal sepsis, as late and/or incomplete procedures may have severely adverse consequences on outcome.

Source control encompasses all measures undertaken to eliminate the source of infection, reduce the bacterial inoculum and correct or control anatomic derangements to restore normal physiologic function. Early control of the septic source can be achieved using both operative and non-operative techniques. An operative intervention remains the most viable therapeutic strategy for managing abdominal sepsis.

The initial aim of the surgical treatment of peritonitis is the elimination of bacterial contamination and inflammatory substances and prevention or reduction, if possible, of fibrin formation. Generally, the surgical source control employed depends on the anatomical source of infection, the degree of peritoneal inflammation and generalized septic response, and the patient’s pre-morbid condition.

Surgical source control entails resection or suture of a diseased or perforated viscus (e.g. diverticular perforation, gastroduodenal perforation), removal of the infected organ (e.g. appendix, gallbladder), debridement of necrotic tissue, resection of ischemic bowel and repair/resection of traumatic perforations with primary anastomosis or exteriorization of the bowel.

The primary objectives of surgical intervention include a) determining the cause of peritonitis, b) draining fluid collections, c) controlling the origin of the abdominal sepsis.

In recent years, laparoscopy has been gaining wider acceptance in the diagnosis and treatment of intra-abdominal infections. Laparoscopic approach in the treatment of peritonitis is feasible and effective without any specific complications in experienced hands. Laparoscopy has the advantage to allow, at the same time, an adequate diagnosis and appropriate treatment with the less invasive abdominal approach. However, in unstable patients laparoscopy is generally avoided because increased intra-abdominal pressure due to pneumoperitoneum seems to have a negative effect in critical ill patients leading to acid–base balance disturbances, as well as changes in cardiovascular and pulmonary physiology.

In certain circumstances, infection not completely controlled may trigger an excessive immune response and sepsis may progressively evolve into severe sepsis, septic shock, and organ failure.

Such patients would benefit from immediate and aggressive surgical treatment with subsequent re-laparotomy strategies, to curb the spread of organ dysfunctions caused by ongoing sepsis.

Three strategies in the management of these difficult patients have been reported:

  • Relaparotomy on demand (when required by the patient’s clinical condition)
  • Planned relaparotomy in the 36-48-h post-operative period (when relaparotomy is planned after first operation)
  • Open abdomen procedure

Choosing the best option is not a simple task. In 2007, van Ruler et al., published a randomized clinical trial comparing on-demand vs. planned relaparotomy strategy in patients with severe peritonitis. Patients in the on-demand relaparotomy group did not have a significantly lower mortality rate or major peritonitis-related morbidity compared with the planned relaparotomy group but they had a substantial reduction in re-laparotomies, health care utilization, and medical costs. However accurate and timely identification of patients who need a relaparotomy is a very difficult decision-making process. At present there are no clinical criteria to select patients for a relaparotomy.

Open abdomen procedure (OA), is defined as intentionally leaving the fascial edges of the abdomen un-approximated (laparostomy). The abdominal contents are exposed and protected with a temporary coverage. The OA technique, when used appropriately, may be useful in the management of surgical patients with severe abdominal sepsis (severe sepsis/septic shock). However, the role of the OA in the management of severe peritonitis is still being debated.

Current clinical guidelines suggest that OA technique should not be used routinely, but individualized for each patient with abdominal sepsis.

The OA concept is closely linked to damage control surgery, and may be easily adapted to patients with advanced sepsis and can incorporate the principles of the Surviving Sepsis Campaign.

Patients may progress to sepsis and septic shock having progressive organ dysfunction, hypotension, myocardial depression and then coagulopathy. These patients are hemodynamically unstable and clearly not optimal candidates for immediate complex operative interventions.  After initial surgery, the patient is rapidly taken to the ICU for physiologic optimization. Early treatment with aggressive hemodynamic support can limit the damage of sepsis-induced tissue hypoxia and may limit the over stimulation of endothelial activity. Following the early hemodynamic support, in principle after 24–48 h, reoperation may be performed with or without final abdominal closure.

In these patients an OA approach may be required for different reasons including:

  • controlling any persistent source of infection,
  • preventing abdominal compartment syndrome and
  • deferring definitive intervention and anastomosis.

The first stage of open abdomen procedure in managing abdominal sepsis is an adequate and prompt source control. The primary objectives of surgical intervention include:

  • determining the cause of peritonitis;
  • draining fluid collections;
  • controlling the origin of the abdominal sepsis.

Once an OA strategy is decided, the optimal method chosen for laparostomy should allow an easy re-entry to the abdominal cavity, and allow for expansion in order to prevent abdominal compartment syndrome.

The second stage of open abdomen procedures involves resuscitation, which should include fluid administration, vasopressive agents and adequate antimicrobial therapy.

In principle, following 24 to 48 h after the initial surgery the patient should be taken back to the operating room for re-operation. Re-operation should be performed within 24–48 h after the initial surgery because exploration of peritoneal cavity with lavage, drainage and source control is feasible.

Following re-exploration, the goal is early and definitive closure of the abdomen, in order to reduce the complications associated with an open abdomen, such as enteroatmospheric fistulas, fascial retraction with loss of abdominal wall domain, and development of massive incisional hernias.

The literature suggests a bimodal distribution of primary closure rates, with early closure depending on post-operative intensive care management and delayed closure depending on the choice of the temporary abdominal closure technique

Early definitive closure is the basis of preventing or reducing the risk of these complications.

The ideal temporary abdominal closure method should protect the abdominal contents, prevent evisceration, allow removal of infected or toxic fluid from the peritoneal cavity, prevent the formation of fistulas, avoid damage to the fascia, preserve the abdominal wall domain, make re-operation easy, safe and facilitate definitive closure. The first and easiest method to perform a laparostomy was the application of a plastic silo (the ‘Bogota bag’). This system is inexpensive, readily available and preserves the intact fascia when sutured to the skin edges. However, it does not provide sufficient traction to the wound edges and allows the fascial edges to retract laterally, resulting in difficult fascial closure under significant tension, especially if the closure is delayed. Negative pressure therapy techniques have become the most extensively used methods for temporary abdominal wall closure. NPT actively drains toxin or bacteria-rich intra-peritoneal fluid and has resulted in a high rate of fascial and abdominal wall closure.

OA as part of a damage control strategy may be a life-saving strategy in a well-selected group of surgical patients with severe abdominal sepsis. Once severe sepsis has been controlled, definitive surgical reconstruction should be performed within 48 h. In 2016 Dublin Consensus Conference for management of intra-abdominal infections the expert panel declared  that there is insufficient evidence to advocate damage control surgery as general strategy in patients with secondary peritonitis and that damage control surgery may be an option in selected significantly physiologically deranged patients with ongoing sepsis.

Massimo Sartelli

References

Sartelli M, Abu-Zidan FM, Ansaloni L, Bala M, Beltrán MA, Biffl WL, et al. The role of the open abdomen procedure in managing severe abdominal sepsis: WSES position paper. World J Emerg Surg. 2015 Aug 12;10:35.

Sartelli M, Catena F, Di Saverio S, Ansaloni L, Malangoni M, Moore EE, et al. World J Emerg Surg. 2014 Mar 27;9(1):22.

Sartelli M, Catena F, Abu-Zidan FM, Ansaloni L, Biffl WL, Boermeester MA, et al.  Management of intra-abdominal infections: recommendations by the WSES 2016 consensus conference. World J Emerg Surg. 2017 May 4;12:22.