Sepsis is the leading cause of morbidity and mortality for critically ill patients, and the tenth leading cause of death overall.1 There are 660,000 to 750,000 cases of sepsis annually. Care of septic patients costs $17 billion in the United States per year ($22,000-$50,000 per patient).2 Sepsis is a continuum of physiologic stages characterized by infection, systemic inflammation, and hypoperfusion with widespread tissue injury. The American College of Chest Physicians and the Society of Critical Care Medicine developed definitions to utilize for sepsis (Table 25-1).3 Risk factors for sepsis include extremes of age, cancer, immunodeficiency, chronic organ failure, genetic factors (male, and non-white ethnic origin in North America), bacteremic patients, and polymorphisms in genes that regulate immunity. Pulmonary, gastrointestinal, genitourinary, and bloodstream infections account for the majority of sepsis cases.4
TABLE 25-1 American College of Chest Physicians/Society of Critical Care Medicine Definitions Related to Sepsis ||Download (.pdf)
TABLE 25-1 American College of Chest Physicians/Society of Critical Care Medicine Definitions Related to Sepsis
|Bacteremia (fungemia)||Presence of viable bacteria (fungi) within the bloodstream|
|Infection||Inflammatory response to invasion of normally sterile host tissue by the microorganisms|
|Systemic inflammatory response syndrome (SIRS)||Systemic inflammatory response to a variety of clinical insults that can be either infectious or noninfectious|
|Sepsis||SIRS secondary to an infection|
|Severe sepsis||Sepsis associated with organ dysfunction, hypoperfusion, or hypotension|
|Septic shock||Sepsis with persistent hypotension despite fluid resuscitation|
|Multiple-organ dysfunction syndrome (MODS)||Presence of altered organ function requiring intervention to maintain homeostasis|
Gram-positive and gram-negative bacteria, fungal species, and viruses cause sepsis. Gram-positive infections account for 30% to 50% of sepsis and septic shock cases. The percentages of gram-negative, polymicrobial, and viral sepsis cases are 25%, 25%, and 4%, respectively.4-7 Multidrug resistant bacteria are responsible for approximately 25% of sepsis cases, aredifficult to treat, and increase mortality. The rate of fungal sepsis increased 200% from 1979 to 2000.
The development of sepsis is complex and multifactorial.8,9 The normal host response to infection is designed to localize and control bacterial invasion and initiate repair of injured tissue through phagocytic cells and inflammatory mediators. The key factor in the development of sepsis is inflammation, which is intended to be a local and contained response to infection or injury. Infection or injury is controlled through pro- and anti-inflammatory mediators. Systemic responses ensue when equilibrium in the inflammatory process is lost.
The clinical presentation of sepsis varies and the rate of development of clinical manifestations may differ from patient to patient (see Tables 25-1 and 25-2 for definitions related to sepsis and the systemic inflammatory response syndrome criteria).3,...