shockintro

the micro-organisms that seem to have itin for us... tum out... to be rather morę like

bystanders____Itis our response to their presence that makes the disease. Our arsenals for fighting

offbacteria are so powerful... that we are morę in danger from them than the invaders.

Lewis Thomas, The Lives of a Celi: Notes of a Biology Watcher, 1974

The normal response to bacterial infection is a complex inflammatory process that attempts to localize the infection and repair the tissue. This response involves the activation of circulating and fixed phagocytic cells, and the generation of both pro-inflammatory and anti-inflammatory mediators. A balance hetween these mediators helps to facilitate tissue healing. Sepsis results when the balance is lost; the inflammatory response to an infection extends beyond the infected tissues, and becomes generalized. The process to control the infection then becomes uncontrolled, unregulated and self-sustaining. It is estimated that 750,000 cases of sepsis are diagnosed annually, and result in morę than 210,000 deaths despite antibiotics and intensive care.

The nonienclature for this section can get confusing. In 1992, the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference (Crit Care Med 1992 Jun;20(6):364-74) agreed on the following definitions:

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Systemie inflammatory response syndrome (SIRS) is a widespread inflammatory response to a variety of severe clinical insults. This syndrome is clinically recognized by the presence of two or morę of the following:

•    Temperaturę >38°C or <36°C

•    Heart ratę >90 beats/min

•    Respiratory ratę >20 breaths/min or PaC02 <32 mmHg

•    WBC >12,000 cells/mm3, <4000 cells/mm3, or with >10 percent immature (band) forms.

Sepsis is the systemie response to infection. So if a patient has sepsis, they have the clinical signs of SIRS with concrete evidence of infection.

Severe sepsis is associated with organ dysfunction, hypoperfusion, or hypotension. Clinical manifestations of hypoperfusion may include lactic acidosis, oliguria, or an acute alteration in mental status.

Septic shock is sepsis with hypotension despite adequate fluid resuscitation combined with perfusion abnormalities that may include. but are not limited to, lactic acidosis, oliguria, or an acute alteration in mental status. Patients who require inotropic or vasopressor support, despite adequate fluid resuscitation, are in septic shock.

Hypotension is defined as a systolic BP of <90 mmHg or a reduction of >40 mmHg from baseline in the absence of other causes for the fali in blood pressure.

Multiple organ failure is the presence of altered organ function in an acutely ill patient such that homeostasis cannot be maintained without intervention.

Bacteremia is the presence of viable bacteria in the blood.