Sepsis is a continuum of physiologic stages characterized by infection, systemic inflammation, and hypoperfusion leading to tissue injury and organ failure (Table 26-1 for definitions to use for sepsis syndromes). Risk factors for sepsis include extremes of age, cancer, immunodeficiency, chronic organ failure, genetic factors (male and non-white ethnic origin in North America), patients with bacteremia, and genetic polymorphisms associated with immune regulation. Pulmonary, gastrointestinal, genitourinary, and bloodstream infections account for the majority of sepsis cases.
The development of sepsis is complex and multifactorial. The key factor in the development of sepsis is inflammation. Infection or injury is controlled through pro- and anti-inflammatory mediators. Systemic responses ensue when there is an overwhelming pro-inflammatory response.
TABLE 26-1Definitions Related to Sepsis ||Download (.pdf) TABLE 26-1 Definitions Related to Sepsis
|Condition ||Definition |
|Bacteremia (fungemia) ||Presence of viable bacteria (fungi) within the bloodstream |
|Infection ||Inflammatory response to invasion of normally sterile host tissue by the microorganisms |
|Sepsis ||Life-threatening organ dysfunction caused by a dysregulated host response noted by ≥2 point increase in SOFA score |
|Septic shock ||Septic patients who display underlying cardiovascular, cellular, and/or metabolic derangements requiring volume resuscitation, have a serum lactate ≥2 mmol/L, and require vasopressor support to maintain a mean arterial pressure ≥65 mm Hg |
|Multiple-organ system failure || |
Presence of altered organ function requiring intervention to maintain homeostasis
The clinical presentation of sepsis varies and the development of clinical manifestations may differ from patient to patient (see Table 26-1). The Sequential (sepsis-related) Organ Failure Assessment (SOFA) score defines those patients with sepsis-related organ dysfunction identified with a score 2 or greater. This score is calculated from various organ system functional assessments including respiratory function, coagulation, hepatic function, cardiovascular function, central nervous system function, and renal function. A rapid, bedside screening tool to identify patients at risk for sepsis-related organ dysfunction is known as the qSOFA or “quick” SOFA score and is considered positive in the presence of any two of the three following criteria: respiratory rate 22 or more, altered mentation, or systolic blood pressure 100 mm Hg or less. The cumulative burden of sepsis complications is the leading factor in mortality. The most common complications are disseminated intravascular coagulation (DIC), acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and hemodynamic compromise.
Gram-positive and gram-negative bacteria are major causes of sepsis, but fungal species and viruses can also cause sepsis. Microbiologic cultures should be obtained before anti-infective therapy is initiated; however, antibiotic therapy should not be delayed until the return of Gram stain or culture data. Cultures take 6 to 48 hours for results to be returned and often reveal no growth of bacterial organisms, but negative cultures do not rule out infection. Rapid identification of bacteria or fungi from blood cultures can be performed on positive blood cultures with results available ...