The objective of these definitions was to give a more differentiated understanding of sepsis to enable precise management. As a result the concept of systemic inflammatory response syndrome (SIRS) evolved with its diagnostic criteria put in place. Then sepsis was defined on the basis of SIRS, whereby sepsis was defined as “suspected or microbiologically proven infection together with SIRS”. Severe sepsis was then defined as “sepsis together with sepsis-induced organ dysfunction”. Finally septic shock was defined as “sepsis-induced hypotension persisting despite adequate fluid resuscitation” (Marik & Lipman, 2007).
A very valid question arises as to the need for such differentiated definitions. There is justification for these differentiated definitions, which is provided from the study of recent data on the mortality rates associated with each of these differentiated definitions. Mortality from sepsis ranges ten to fifteen percent; severe sepsis ranges from seventeen to twenty percent and septic shock ranges from forty-three to fifty-four percent. Thus the hierarchical definitions get justified by this. (Marik & Lipman, 2007).
Deeper examination of this data suggests that there is a wide difference in the mortality figures for severe sepsis and septic shock. This finding clearly indicates that it is most important to distinguish between severe sepsis and septic shock, so that they can be grouped into low and high mortality risk groups. It is in this aspect that the hierarchical definitions as created in 1991 are found to be deficient. The diagnostic criteria for septic shock still remain unclear and vague. To remove this deficiency Marik and Lipman, 2007, suggest that septic shock be defined as “ a systolic blood pressure less than 90mmHg (or a fall in systolic blood pressure of > 40mmHg), or a mean arterial pressure less than 65mmHg after a crystalloid fluid challenge of