Medical therapy

The general principles guiding the treatment of intra-abdominal infections are 4-fold:

1) to control the infectious source;

2) to eliminate bacteria and toxins;

3) to maintain organ system function;

4) to control the inflammatory process.

Medical, nonoperative interventional, and operative treatment options are complimentary, not competitive, in the treatment of peritoneal infections.

Medical support includes:

1) systemic antibiotic therapy;

2) intensive care with haemodynamic, pulmonary, and renal replacement support;

3) nutrition and metabolic support;

4) inflammatory response modulation therapy.

Treatment of peritonitis and intra-abdominal sepsis always begins with volume resuscitation, correction of potential electrolyte and coagulation abnormalities, and empiric broad-spectrum parenteral antibiotic coverage.

Antibiotic therapy. It is based on culture results.

Third-generation cephalosporin:

Gram-negative E. coli.

Enterobacter species.

Klebsiella species.

Proteus species.

Second-generation cephalosporin, penicillins with anaerobic activity, quinolones with anaerobic activity, quinolone and metronidazole, aminoglycoside and metronidazole:

Gram-positive Streptococcus species.

Enterococcus species.

Anaerobic Bacteroides fragiles.

Other Bacteroides species.

Eubacterium species.

Clostridium species.

Anaerobic Streptococcus species.

Tertiary Gram-negative Enterobacter species.

Pseudomonas species.

Enterococcus speciez second-generation cephalosporin.

Carbapenems.

Triazolesoramphotericin(considered in fungal aetiology).

Several studies suggest that antibiotic therapy is not as effective in later stages of the infection and that early (preoperative) systemic antibiotic therapy can result in significant reduction of concentration and growth rates of viable bacteria in the peritoneal fluid. Therefore, begin empiric therapy as soon as the diagnosis of peritoneal infection is suspected. The initial therapy for acute peritonitis must be mainly active against gram-negative organisms (E. coli, Enterobacteriaceae species) and anaerobes (e.g., B. fragilis).

In severe and hospital-acquired intra-abdominal infections, imipenem, piperacillin/tazobactam, and a combination of aminoglycosides and metronidazole are often effective.

Carbapenem is effective compared to piperacillin or tazobactam in the treatment of complicated intra-abdominal infection and was well tolerated.

Additional clinical antimicrobial studies are underway investigating the efficacy of new quinolones in the treatment of intra-abdominal infection.

The optimal duration of antibiotic therapy must be individualized and depends on the underlying pathology, severity of infection, speed and effectiveness of source control, and the patient response to therapy.

In uncomplicated peritonitis with early adequate source control, a course of 5–7 days is adequate in most cases. Complicated persistent infections and infections in patients who are immunocompromised may warrant a prolonged course of antibiotic therapy.

Some patients demonstrate persistent signs of inflammation without a defined infectious focus. In these patients, continued broad-spectrum antibiotic therapy may be more useful.

Nonoperative drainage. Today, abundant literature documents the safety and efficacy of Ultrasonic- and CT-guided percutaneous drainage of abdominal and extraperitoneal abscesses.

Common reasons for failure of primary nonoperative management include enteric fistula (e.g., anastomotic dehiscence), pancreatic involvement, infected clot, and multiple or multilocated abscesses.

In peritoneal abscess formation caused by subacute bowel perforation (e.g., diverticulitis, Crohn’s disease, appendicitis), primary percutaneous management with percutaneous drainage was successful in most patients.

Surgical treatment

Surgery remains an important therapeutic modality for all cases of peritoneal infection. Any operation should address the first 2 principles of the treatment of intra-peritoneal infections: early and definitive source control and elimination of bacteria and toxins from the abdominal cavity.

The operative approach is directed by the underlying disease process and the type and severity of the intra-abdominal infection. The surgeon should always strive to arrive at a specific diagnosis and delineate the intra-abdominal anatomy as accurately as possible prior to the operation.

However, in severe abdominal sepsis, a delay of operative management may lead to a significantly higher need for reoperations and overall worse outcomes; early exploration may be indicated.

Open-abdomen technique and scheduled reoperation

In certain situations, staging the operative approach to intraperitoneal infections is appropriate. Staging may be performed as a scheduled second-look operation or through open management, with or without temporary closure (laparostomy).

Second-look operations may be used in a “damage control” manner. In these cases, the patient at initial operation is severely ill and unstable from septic shock or coagulopathy (e.g., mediator liberation, disseminated intravascular coagulation). The goal of the initial operation is to provide preliminary drainage and to remove obviously necrotic tissue.

Then, the patient is resuscitated and stabilized for 24–36 hours and returned to the operating room for a more definitive drainage and source control.

In conditions related to bowel ischaemia, the initial operation aims to remove all frankly devitalized bowel. The second-look operation serves to reevaluate for further demarcation and decision-making regarding reanastomosis or diversion.

In severe peritonitis, particularly with extensive retroperitoneal involvement (e.g., necrotizing pancreatitis), open treatment with repeat reexploration, debridement and intraperitoneal lavage has been shown to be effective.

Temporary closure of the abdomen to prevent herniation and contamination from the outside of the abdominal contents can be achieved using gauze and large, impermeable, self-adhesive membrane dressings, mesh (e.g., Vicryl, Dexon), nonabsorbable mesh (GORE-TEX, polypropylene) with or without zipper or Velcrolike closure devices, and vacuum-assisted closure (VAC) devices. Advantages of this management strategy include avoidance of abdominal compartment syndrome (ACS) and easy access for reexploration. The disadvantages include significant disruption of respiratory mechanics and potential contamination of the abdomen with nosocomial pathogens.

Gastrointestinal decompression. It is indicated in patients with severe peritonitis and ileus. It is achieved by transnasal, transstomal or transanal small or/and large bowel tube. The aims of procedure are:

– removing of toxic bowel content;

– stabilization of bowel motor function;

– enteral nutritional supporting;

– prevention of postoperative adhesion bowel obstruction.

Laparoscopy

Laparoscopy is gaining wider acceptance in the diagnosis and treatment of abdominal infections. Initial laparoscopic examination of the abdomen can assist in determination of the aetiology of peritonitis. Laparoscopic diagnosis and peritoneal lavage in patients with peritonitis secondary to diverticulitis without faecal peritoneal contamination has helped to avoid operation in most patients in small clinical trials.

Successful laparoscopic repair of perforated gastric and duodenal ulcers has also been reported.

The treatment of perihepatic infections via laparoscopic approach has been well established in acute cholecystitis, where laparoscopic cholecystectomy has become the mainstay of therapy. More recently, primary treatment of subphrenic abscesses and laparoscopic Ultrasonic-assisted drainage of pyogenic liver abscesses have been performed successfully.

Individual reports also describe successful drainage of peripancreatic fluid collections and complicated intra-abdominal abscesses that are not amenable to CT scan – or Ultrasonic-guided percutaneous drainage.

As minimally invasive procedures continue to advance technologically, use of these approaches is likely to increase, reducing the need for the open surgical approach for peritoneal abscess drainage.

Preoperative details

Volume resuscitation and prevention of secondary organ system dysfunction are of utmost importance in the treatment of patients with intra-abdominal infections. Depending on the severity of the disease, these patients should have Foley catheters placed to monitor urine output. Use invasive haemodynamic monitoring in severely ill patients to guide volume resuscitation and inotropic support. Correct existing serum electrolyte disturbances and coagulation abnormalities as best as possible before any intervention.

Begin empiric broad-spectrum systemic antibiotic therapy as soon as the diagnosis of intra-abdominal infection is suspected. Remember that patients with peritonitis often have severe abdominal pain. Provide adequate analgesia with parenteral narcotic agents as soon as possible. In the setting of significant nausea, vomiting, or abdominal distension caused by obstruction or ileus, institute nasogastric decompression as soon as possible. Consider intubation and ventilator support early in patients with evidence of septic shock or altered mental status to prevent further decompensation.

In patients with severe infections and certain disease processes (e.g., necrotizing pancreatitis, bowel ischaemia), informed consent should include the potential need for several reoperations and enteric diversion. The involved physicians and surgeon should not downplay the significant morbidities associated with abdominal sepsis when discussign these issues with the patient and/or family.

Intraoperative details

A vertical midline incision is the incision of choice in most patients with generalized peritonitis because it allows access to the entire peritoneal cavity. In patients with localized peritonitis (e.g., acute appendicitis, cholecystitis), an incision directly over the site of pathology (e.g., right lower quadrant, right subcostal) is usually adequate.

In patients with an unclear aetiology of the peritonitis, initial diagnostic laparoscopy may be useful.

The intra-abdominal anatomy may be significantly distorted because of inflammatory masses and adhesions. The inflamed organs are often very friable, and the surgeon must exercise great caution when exploring the patient with peritoneal infection.

Haemodynamic instability may occur at any time during treatment because of bacteremia and cytokine release. Patients often demonstrate significant fluid shifts with third spacing. Swelling of the bowel, retroperitoneum, and abdominal wall may preclude safe abdominal closure after prolonged cases in patients who are severely ill.

Inflammation causes regional hyperemia, and sepsis may cause coagulation deficits and platelet dysfunction, leading to increased bleeding. Careful dissection and meticulous haemostasis are of utmost importance.

One of the critical decisions in the surgical treatment of patients with severe peritonitis is regarding whether to use a closed-abdomen or open-abdomen technique. The goal of the closed-abdomen technique is to provide definitive surgical treatment at the initial operation; perform primary fascial closure and perform repeat laparotomy only when clinically indicated. The goal of the open-abdomen technique is to provide easy direct access to the affected region. Source control is achieved through repeated reoperations or open packing of the abdomen. This technique may be well suited for initial damage control in extensive peritonitis. Also consider patients who are at high risk for development of abdominal compartment syndrome (e.g., intestinal distension, extensive abdominal wall and intra-abdominal organ oedema) for this technique because attempts to perform primary fascial closure under significant tension in these circumstances are associated with an increased incidence of multiorgan faluation (e.g., renal, respiratory), necrotizing abdominal wall infections, and mortality.

Postoperative details

Postoperatively, monitor all patients closely in the appropriate clinical setting for adequacy of volume resuscitation, resolution or persistence of sepsis, and the development of organ system failure. Appropriate systemic broad-spectrum antibiotic coverage must be continued without interruption for the appropriate time.

The patient’s overall condition should improve significantly and progressively within 24–72 hours of the initial treatment (i.e., resolution of the signs and symptoms of infection, mobilization of interstitial fluid). This time course may be prolonged in patients who are critically ill with significant multiple organ system dysfunction. A lack of improvement should prompt an aggressive search for a persistent or recurrent intraperitoneal or new extraperitoneal infectious focus.

Patients requiring surgical intervention for peritonitis demonstrate a significantly increased risk for surgical site infections and wound healing failure.

All patients who are critically ill and patients receiving prolonged antibiotic therapy are at increased risk for developing secondary opportunistic infections (e.g., fungal infections, central venous catheter infections, ventilator-associated pneumonia).

Nutrition. In general, patients with peritonitis develop some degree of gut dysfunction (ileus) after exploration. If enteral feeding is contraindicated or not tolerated, parenteral nutrition should be instituted.

Follow-up care

After resolution of peritonitis and peritoneal abscesses, follow-up care is directed mostly by specifics of the underlying disease process and the presence or absence of chronic complications (e.g., enterocutaneous fistulae).