Critical Care Medicine 978-1-4963-0291-5 chapter 27

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SECTION II • Medical and Surgical Crises

SYSTEMIC INFLAMMATORY

RESPONSE SYNDROME (SIRS)

SEPSIS

INFECTION

eventually regain premorbid levels of function in most organs; however, there is a growing aware- ness that a significant proportion of patients are left with long-lasting cognitive and neuromuscular impairments (see Chapter 18). The average survivor requires 7 to 14 days of intensive care support, with much of this time spent receiving mechanical ven- tilation. After intensive care unit (ICU) discharge, an additional 10- to 14-day hospital stay is typical. Thus, the hospital length of stay for survivors aver- ages 3 to 5 weeks. Massive hospital bills are often generated during the care of septic shock even when the course of treatment and recovery are relatively uncomplicated. After hospital discharge, long-term skilled inpatient care or challenging home care and rehabilitation are often required. Most survivors of septic shock are discharged on numerous medica- tions, require office visits to physicians frequently during the year after discharge, and are readmitted one or more times for treatment of complications. RELATIONSHIP OF INFECTION TO SEPSIS Recovery of a pure growth of a pathogen from a normally sterile site (e.g., blood or joint or cerebro- spinal fluid [CSF]) diagnoses infection ; however, most infected patients do not develop overt sepsis. This fact suggests that it is not infection per se that is etiologic but rather the combination of infection and host response that determines if an individual will develop organ dysfunction. Interestingly, a clear microbiologic explanation is absent in many patients, even though cultures grow some organism 60% to 80% of the time. Many of these “positive” cultures are obtained long after symptomatic sepsis or septic shock is established and represent insignifi- cant colonization, contamination, or superinfection. FIGURE 27-1.  Formerly prevailing classification of systemic inflammatory states. In this nosology, SIRS is defined by a specific pattern of vital sign abnormali- ties. Infection is the presence of a microbe within the host at a normally sterile site. When infection causes SIRS, the resulting syndrome is called sepsis (central overlap). If an organ failure results from sepsis, the syndrome is called severe sepsis.

SEVERE SEPSIS

SEVERE SIRS

Victims of trauma, immunosuppressed patients, and patients with chronic debilitating medical conditions (e.g., diabetes, chronic obstructive lung disease) or those undergoing complicated surgical procedures are most at risk. Overall, approximately 30% of patients with sep- tic shock die despite receiving “standard therapy” consisting of antimicrobial therapy and organ system support with fluids, vasoactive drugs, mechanical ventilation, dialysis, and nutrition. Such statistics motivate continuing efforts to recognize and optimally treat this high-risk patient group, as exemplified by the recurring Surviving Sepsis campaigns. Elderly and hypothermic patients have a substantially worse prognosis than those without these factors; however, the best practical clinical predictor of outcome is the number of dysfunctional organ systems. Among the possible organ failures, circulatory failure (shock) has a disproportionately negative prognostic value. Morbidity and mortality from septic shock remain unacceptably high, and billions of dollars are spent caring for this desperately ill group of patients. Fortunately, survivors usually

INFECTION

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SEPSIS

SEPTIC SHOCK

FIGURE 27-2. Suggested revision of the classification scheme for septic conditions.

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