<prompt> Which of the following differentiates SIRS from sepsis -Heart rate 90minTemperature 38 degreesAbsence of definitive evidence of infectionWBC 12000 cells mm3  <response>: Ans. is c i.e., Absence of definitive evidence of infection It is worth noting that Sepsis is the systemic response to infection and is defined as the presence of SIRS in addition to a documented infection.Definitions of sepsis, SIRS, severe sepsis, septic shockSystemic inflammatory response syndrome SIRS: Clinically recognized by the prescence of two or more of the following temperature 30deg or 36degCHeart rate 90 beatsminRespiratory rate 20 breathsmin or PaCO2 32 mmHgWBC 12,000 cellsmin3 4000 cellsmin3, or 10 immature band formsSepsis: systemic response to infection. Thus the clinical signs decribing SIRS are present, together with definitive evidence of infection.Severe sepsis: Severe when it is associated with organ dysfunction, hypoperfusion, or hypotension. The manifestations of hypoperfusion may include, but are not limited to, lactic acidosis, oliguria, or acute alteration in mental status.Septic shock : Sepsis with hypotension despite adequate fluid resuscitation combined with perfusion abnormalities that may include, but are not limited to, lactic acitosis, oliguria, or acute alteration in mental status. Patients who are on inotropic or vasopressor agents may not hypotensive at the time perfusion abnormalities are measure.Hypotension : Systolic blood pressure of 90 mmHg or a reduction of 40 mgHg from baseline in the absence of other causes for the fall in blood pressure. 