The following is from Emedicine/Medscape Pediatric Sepsis accessed 1/31/2015
The spectrum of sepsis ranges from microbial invasion of the bloodstream or intoxication with early signs of circulatory compromise—including tachycardia, tachypnea, peripheral vasodilation, and fever (or hypothermia)—to full-blown circulatory collapse with multiple organ dysfunction syndrome (MODS) and death (see the image below).
Pathogenesis of sepsis and multiple organ dysfunction syndrome (MODS) [Above Figure].
All these manifestations are part of what is more appropriately termed the systemic inflammatory response syndrome (SIRS), which may be caused by noninfectious or infectious conditions. SIRS results from an insult (infectious, traumatic, chemical, malignant, autoimmune, or idiopathic) and the host response to the insult. The outcome depends on the intricate interplay of upregulating and downregulating cytokines and inflammatory cells and the direct effects of the insult itself. Sepsis is SIRS developing in conjunction with infection.
Experts have come together to develop a consensus on definitions of sepsis, SIRS, severe sepsis, and septic shock that are appropriate for the pediatric population.Age-related variables have been applied to the definition of SIRS and sepsis. The definition of SIRS now requires either fever or white blood cell (WBC) abnormality.
The earliest, mildest manifestation of SIRS is typified by the triad of hyperthermia (or hypothermia), tachypnea, and tachycardia. If SIRS is identified and reversed early, the subsequent inflammatory cascade can often be avoided or mitigated. However, in some situations, further damage occurs because the insult or the resultant host immune response is too great. This damage can result in increased cardiac output, peripheral vasodilation, increased tissue oxygen consumption, and a hypermetabolic state (ie, warm shock).
If SIRS is not identified and reversed early, cardiac output may fall, peripheral vascular resistance may increase, and shunting of blood may ensue (ie, cold shock). This results in tissue hypoxia, end-organ dysfunction, metabolic acidosis, end-organ injury or failure, and death.