Septic Shock:

Multiorgan Dysfunction Syndrome
Sepsis is described as an autodestructive process that permits the extension of normal pathophysiologic response to infection (involving otherwise normal tissues), resulting in multiple organ dysfunction syndrome. Organ dysfunction or organ failure may be the first clinical sign of sepsis, and no organ system is immune to the consequences of the inflammatory excesses of sepsis.

Circulation


Central circulation


Regional circulation


Hypotension

Pulmonary dysfunction

Endothelial injury in the pulmonary vasculature leads to disturbed capillary blood flow. As many as 40% of patients with severe sepsis develop acute lung injury.

Acute lung injuryThe acute lung injury may be reversible at an early stage, but, in many cases, the host response is uncontrolled, and the acute lung injury progresses to ARDS.
Gastrointestinal dysfunction and nutrition

The gastrointestinal tract may help to propagate the injury of sepsis. Overgrowth of bacteria in the upper gastrointestinal tract may aspirate into the lungs and produce nosocomial pneumonia. The gut's normal barrier function may be affected, thereby allowing translocation of bacteria and endotoxin into the systemic circulation and extending the septic response. Septic shock usually causes ileus, and the use of narcotics and sedatives delays the institution of enteral feeding. The optimal level of nutritional intake is interfered with in the face of high protein and energy requirements.

Liver dysfunction

Renal dysfunction

Central nervous system dysfunction


Mechanisms of Organ Dysfunction and Injury

Hypoxic hypoxia

Direct cytotoxicity

Apoptosis (programmed cell death)

Immunosuppression


Coagulopathy


Characteristics of Sepsis that Influence Outcomes
Clinical characteristics that relate to the severity of sepsis include the following:
•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

Frequency
United States
Since the 1930s, studies have shown an increasing incidence of sepsis. In 1 study, the incidence of bacteremic sepsis (both gram-positive and gram-negative sepsis) increased from 3.8 cases per 1000 admissions in 1970 to 8.7 cases per 1000 admissions in 1987. The incidences of nosocomial blood stream infection in 1 institution from 1980-1992 increased from 6.7 to 18.4 cases per 1000 discharges. The increase in the number of patients who are immunocompromised and an increasing use of invasive diagnostic and therapeutic devices predisposing to infection are major reasons for the increase in incidences of sepsis.

The incidence of sepsis syndrome and septic shock in patients admitted to a university hospital was reportedly 13.6 and 4.6 cases per 1000 persons, respectively. In the United States, 200,000 cases of septic shock and 100,000 deaths per year occur from this disease.

A recently published article reported the incidence, cost, and outcome of severe sepsis in the United States. Analysis of a large sample from the major centers reported the incidence of severe sepsis as 3 cases per 1000 population, and 2.26 cases per 100 hospital discharges. Out of these cases, 51.1% received intensive care admission, an additional 17.3% were cared for in intermediate care or coronary care unit. Incidence ranged from 0.2 cases per 1000 admissions in children to 26.2 cases per 1000 admissions in individuals older than 85 years. The mortality rate was 28.6% and ranged from 10% in children to 38.4% in elderly people. Severe sepsis resulted in an average cost of $ 2200 per case, with an annual total cost of $16.7 billion nationally.5

Mortality/Morbidity
The mortality rate in patients with sepsis varies in the reported series from 21.6-50.8%. Over the last decade, mortality rates seem to have decreased. In some studies, the mortality rate specifically caused by the septic episode itself is specified and is 14.3-20%.


Septic Shock: eMedicine Critical Care