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What is meant by SIRS, sepsis and septic
shock?
For many years doctors, attending intensive care units, used a variety of
terms to describe illnesses associated with infection, or illness that
looked like infection. These terms included sepsis, septicemia,
bacteremia, infection, septic shock, toxic shock etc. Unfortunately there
were two problems with these terms: 1. There were no strict definitions
for the terms used, and often these words or phrases were used
incorrectly. 2, An emerging body of evidence arose which led us to believe
that systemic inflammation, rather than infection, was responsible for
multi-organ failure. In the early 1990s a consensus conference between the
ACCP and the SCCM laid out a new series of definitions for what is
inflammation and what is sepsis
(3).
The terminology has come into common usage, albeit with some reservations
(4;5)
,
and I recommend that you learn and use these definitions.
ACCP/SCCM Consensus
Conference Definitions (3)
Please note
that these definitions have recently been revised: the new definitions
will be published in the summer of 2002.
Infection
A host
response to the presence of micro-organisms or tissue invasion by
microorganisms.
Bacteremia.
The presence of viable
bacteria in circulating blood
Systemic Inflammatory
Response Syndrome (SIRS)
The systemic
inflammatory response to a wide variety of severe clinical insults,
manifested by two or more of the following conditions:
-
Temperature > 38°C or
< 36°C
-
Heart rate > 90
beats/min
-
Respiratory rate > 20
breaths/min or PaCO2 < 32 mm Hg
-
WBC count > 12,000/mm3
, < 4000/mm3 , or > 10% immature (band) forms.
Sepsis
The systemic
inflammatory response to infection. In association with infection,
manifestations of sepsis are the same as those previously defined for
SIRS. It should be determined whether they are a direct systemic response
to the presence of an infectious process and represent an acute alteration
from baseline in the absence of other known causes for such abnormalities.
The clinical manifestations would include two or more of the following
conditions as a result of a documented infection:
Severe Sepsis/SIRS.
Sepsis (SIRS)
associated with organ dysfunction, hypoperfusion, or hypotension.
Hypoperfusion and perfusion abnormalities may include, but are not limited
to, lactic acidosis, oliguria, or an
acute alteration in mental status.
Refractory (Septic)
Shock/SIRS Shock.
A subset of severe
sepsis (SIRS) and defined as sepsis (SIRS) induced hypotension despite
adequate fluid resuscitation along with the presence of perfusion
abnormalities that may include, but are not limited to, lactic acidosis,
oliguria, or an acute alteration in
mental status. Patients receiving inotropic or vasopressor agents may no
longer be hypotensive by the time they manifest hypoperfusion
abnormalities or organ dysfunction, yet they would still be considered to
have septic (SIRS) shock.
Multiple Organ
Dysfunction Syndrome (MODS).
Presence of altered
organ function in an acutely ill patient such that homeostasis cannot be
maintained without intervention.
References
CLICK HERE FOR REFERENCES
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