Background
Sepsis is uncontrolled infection—a potentially fatal condition manifested by tachycardia, leukocytosis, fever, and hypotension. In the United States, the overall incidence is estimated to be more than 1.1 million cases per year at an annual cost of $24.3 billion. More than 70% of septic patients have associated comorbidities, and more than 60% of episodes occur in persons aged 65 years and older. Despite advances in antimicrobial agents, supportive care, and surgical management, the in-hospital mortality rate ranges from 14.7% to 29.9%.
Conditions that can progress to abdominal sepsis include perforated peptic ulcer, diverticulitis, cholecystitis, appendicitis, pancreatitis, bowel ischemia, trauma, and deep space abscesses. Specific colorectal-related causes of sepsis include anastomotic leaks, perforation from diverticulitis, malignant or benign obstructions, inflammatory strictures, enterocutaneous fistula and fistula-in-ano, postoperative intra-abdominal abscesses, and unrecognized bowel injury, especially in patients undergoing a repeat operation. Treatment of sepsis by control of the septic focus, prompt institution of antimicrobial agents, and goal-directed fluid therapy is usually successful. This chapter presents the principles upon which effective treatment of abdominal sepsis is based.
Prevention
Defining Risk
Smoking, poorly controlled diabetes mellitus, radiation exposure, immunodeficiency, steroid and other immunosuppressant use, extremes of age, hypothermia, malnutrition, shock, and a lengthy preoperative inpatient course are all significant risk factors for sepsis in surgical patients. Wound status is also important. The National Research Council categorized wounds into four classes in an effort to better predict infection rates for closed wounds ( Table 84-1 ). Wounds classified as contaminated or dirty along with any surgery lasting longer than 2 hours, any intra-abdominal procedure, and the presence of three or more associated medical diagnoses at the time of discharge were found to be independent risk factors for surgical site infections. The number of risk factors present helps to better predict the risk of postoperative infection.
| Class | Definition | Example | Risk of Wound Infection |
|---|---|---|---|
| Clean | Atraumatic No entry into respiratory, urinary, gastrointestinal, or biliary tracts No inflammation No break in sterile technique | Breast biopsy | 1%–3% |
| Clean–contaminated | Controlled entry into respiratory, urinary, gastrointestinal, or biliary tracts Minor break in sterile technique | Elective bowel resection | 5%–10% |
| Contaminated | Traumatic wound, gross spillage from gastrointestinal tract Acute nonpurulent infection Major break in sterile technique | Appendectomy for acute appendicitis | 15% |
| Dirty | Existing purulent infection Perforated viscus | Hartmann procedure for perforated diverticulitis | 40% |
Preventive Measures
Bowel Preparation
The use of mechanical bowel preparation prior to elective bowel resection aims to decrease the total bacterial load and minimize the possibility of fecal contamination of the abdomen while improving the technical ease of the operation. However, numerous recent studies have shown similar perioperative infection rates with and without the use of bowel preparation. For emergency operations, mainly obstructions, intraoperative colonic lavage is effective in clearing retained stool.
Prophylactic Antibiotics
The timely administration of perioperative parenteral antibiotics (given at the time of induction) aimed at anaerobes and gram-negative rods is geared toward achieving high systemic antibiotic levels at the time of greatest risk for contamination. Repeat dosing is encouraged for longer cases and is determined by the half-life of the antibiotic chosen. A common choice for patients undergoing bowel resection is ampicillin-sulbactam (Unasyn), 3 g administered via intravenous piggyback upon the call to the operating room, with repeat dosing at 3-hour intervals, or long-acting ertapenem (Invanz).
Intact Anastomosis
A safe, tension-free, well-vascularized anastomosis is the most critical part of any colorectal restorative resection. Anastomotic dehiscence is a primary cause of postoperative intra-abdominal sepsis. Therefore, techniques that decrease the risk of anastomotic leakage will also decrease the risk of postoperative abdominal sepsis.
Tension-Free Anastomosis
For left colectomy or anterior resection, tension-free anastomosis is best achieved through full mobilization of the splenic flexure, high ligation of the inferior mesenteric artery, and transection of the inferior mesenteric vein at the level of the ligament of Treitz. For ileal J pouch anal anastomoses, the terminal ileum must be fully mobilized by dissecting the retroperitoneum to the level of the duodenum. Occasionally, division of the ileocolic artery is necessary to achieve a tension-free anastomosis.
Well-Vascularized Anastomosis
Good blood supply is critical in minimizing most anastomotic complications (leak, stricture, or outright failure). Although many new technological advances have been made in assessing the blood flow to an anastomosis (e.g., FIREFLY and SPY), seeing pulsatile flow from the cut edge of the mesentery and bowel is sufficient.
Consideration for Diversion
An astute surgeon may prevent an anastomotic leak by opting to avoid primary anastomosis when patient or procedural risk for anastomotic dehiscence is high. Here one or both bowel ends are brought out as stomas. A second strategy, using a diverting stoma proximal to a primary anastomosis, will facilitate the management of an anastomotic leak and minimize the severity of the ensuing sepsis. An anastomosis should be avoided or at least diverted in the settings of radiation exposure/damage, hypotension, vasopressors, high-dose corticosteroids, recent use of biologic immunosuppressive agents and certain chemotherapeutic agents, preoperative albumin levels lower than 3.0 g/dL, intraoperative blood loss of 500 mL or more, operative time of 200 minutes or more, and/or the need for intraoperative transfusion.
Appropriate Use of Drains
Although there is no role for the routine use of drains in the prevention of intra-abdominal sepsis, drains are frequently needed in its management. A well-placed drain, often placed with CT or ultrasound guidance, along with appropriate antibiotic coverage, will sometimes prevent the need for a patient to undergo re-exploration for postoperative sepsis. Once cultures results are obtained, antibiotic coverage may be tailored accordingly.
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