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Prognosis
The mortality rate of severe sepsis and septic shock is frequently quoted as anywhere from 20% to 50%. In some studies, the mortality rate specifically caused by the septic episode itself is specified and is 14.3-20%.
In recent years, mortality rates seem to have decreased. The National Center for Health Statistics study showed a reduction in hospital mortality rates from 28% to 18% for septicemia over the years; however, more overall deaths occurred due to the increased incidence of sepsis. The study by Angus et al, which likely more accurately reflects the incidence of severe sepsis and septic shock, reported a mortality rate of about 30%.[19]
Given that there is a spectrum of disease from sepsis to severe sepsis to septic shock, mortality varies depending on the degree of illness. The following clinical characteristics are related to the severity of sepsis:
?An abnormal host response to infection
?Site and type of infection
?Timing and type of antimicrobial therapy
?Offending organism
?Development of shock
?Any underlying disease
?Patient’s long-term health condition
?Location of the patient at the time of septic shock
Factors consistently associated with increased mortality in sepsis include advanced age, comorbid conditions, and clinical evidence of organ dysfunction.[19, 24] One study found that in the setting of suspected infection, just meeting SIRS criteria without evidence of organ dysfunction did not predict increased mortality; this emphasizes the importance of identifying organ dysfunction over the presence of SIRS criteria.[24] However, there is evidence to suggest that meeting increasing numbers of SIRS criteria is associated with increased mortality.[26]
In patients with septic shock, several clinical trials have documented a mortality rate of 40-75%. The poor prognostic factors are advanced age, infection with a resistant organism, impaired host immune status, poor prior functional status, and continued need for vasopressors past 24 hours. Development of sequential organ failure, despite adequate supportive measures and antimicrobial therapy, is a harbinger of poor outcome. The mortality rates were 7% with SIRS, 16% with sepsis, 20% with severe sepsis, and 46% with septic shock.[27]
A link between impaired adrenal function and higher septic shock mortality has been suggested. The adrenal gland is enlarged in patients with septic shock compared with controls. A study by Jung et al found that an absence of this enlargement, indicated by total adrenal volume of less than10 cm3, was associated with increased 28-day mortality in patients with septic shock.[28]
In 1995, a multicenter prospective study published by Brun-Buisson (1995) reported a mortality rate of 56% during ICU stays and 59% during hospital stays.[4] Twenty-seven percent of all deaths occurred within 2 days of the onset of severe sepsis, and 77% of all deaths occurred within the first 14 days. The risk factors for early mortality in this study were higher severity of illness score, the presence of 2 or more acute organ failures at the time of sepsis, shock, and a low blood pH (< 7.3).
Studies have shown that appropriate antibiotic administration (ie, antibiotics that are effective against the organism that is ultimately identified) has a significant influence on mortality. For this reason, initiating broad-spectrum coverage until the specific organism is cultured and antibiotic sensitivities are determined is important.
The long-term use of statins appears to have a significant protective effect on sepsis, bacteremia, and pneumonia.[29]
End-organ failure is a major contributor to mortality in sepsis and septic shock. The complications with the greatest adverse effect on survival are ARDS, DIC, and ARF. (See Clinical Presentation.)
The frequency of ARDS in sepsis has been reported from 18-38%, the highest with gram-negative sepsis, ranging from 18-25%. Sepsis and multiorgan failure are the most common cause of death in ARDS patients. Approximately 16% of patients with ARDS died from irreversible respiratory failure. Most patients who showed improvement achieved maximal recovery by 6 months, with the lung function improving to 80-90% of predicted values.
Controversy exists over the use of etomidate as an induction agent for patients with sepsis, with debate centered on its association with adrenal insufficiency. Sprung et al, in the CORTICUS study, reported that patients who received etomidate had a significantly higher mortality rate than those who did not receive etomidate.[30]
However, the authors did not address the fact that those patients receiving etomidate required orotracheal intubation and thus were a sicker subset. There have been no studies to date that have prospectively evaluated the effect of single-dose etomidate on the mortality of septic shock.
Although sepsis mortality is known to be high, its effect on the quality of life of survivors was previously not well characterized. New evidence shows that septic shock in elderly persons leads to significant long-term cognitive and functional disability compared with those hospitalized with nonsepsis conditions. Septic shock is often a major sentinel event that has lasting effects on the patient’s independence, reliance on family support, and need for chronic nursing home or institutionalized care.[31]
http://emedicine.medscape.com/article/168402-overview#aw2aab6b2b5 |
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楼主: Rose2013
狗仔卡
发表于 2012-7-30 00:20:14
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