TABLE 45–1Definitions Related to Sepsis |Favorite Table|Download (.pdf) TABLE 45–1 Definitions Related to Sepsis
|Condition ||Definition |
|Bacteremia (fungemia) ||Presence of viable bacteria (fungi) in the bloodstream |
|Infection ||Inflammatory response to invasion of normally sterile host tissue by the microorganisms |
|SIRS ||Systemic inflammatory response to a variety of clinical insults, which can be infectious or noninfectious. The response is manifested by two or more of the following conditions: temperature >38°C (>100.4°F) or <36°C (<96.8°F); HR >90 beats/min; RR >20 breaths/min or PaCO2<32 mm Hg (<4.3 kPa); WBC >12,000 cells/mm3 (>12 × 109/L), <4,000 cells/mm3 (<4 × 109/L), or >10% (>0.10) immature (band) forms |
|Sepsis || |
SIRS secondary to suspected or documented infection
Additional criteria include general variables (altered mental status, positive fluid balance of >20 mL/kg over 24 hours, hyperglycemia >120 mg/dL [>6.7 mmol/L]); inflammatory variables (plasma C-reactive protein/procalcitonin >2 SD above normal value); hemodynamic variables (arterial hypotension <90mm Hg (<12.0 kPa) or MAP <70 mm Hg (<9.3 kPa), elevated mixed venous oxygen saturation of >70% (>0.70); CI >3.5 L/min (>0.058 L/s); organ-dysfunction variables (arterial hypoxemia; acute oliguria of <0.5ml/kg/hr or 45 ml/hr for at least 2 hr, creatinine increase >0.5 mg/dL (>0.44 μmol/L), coagulation abnormalities, paralytic ileus, platelets <100,000 /mm3 (<100 × 109/L), bilirubin >4 mg/dL (>68 μmol/L); tissue-perfusion variable (hyperlactatemia >1 mmol/L, decreased capillary refill)
|Severe sepsis ||Sepsis associated with one or more organ dysfunctions, hypoperfusion, or hypotension. Hypoperfusion and perfusion abnormalities may include but not limited to arterial hypoxemia (PaO2 /FiO2<300) lactic acidosis, oliguria, increase in creatinine, coagulation abnormalities (INR>1.5), and elevated bilirubin |
|Septic shock ||Sepsis with persistent hypotension despite fluid resuscitation (intravenous fluid of 30 mL/kg) or hyperlactatemia >1 mmol/L |
ETIOLOGY AND PATHOPHYSIOLOGY
The sites of infections that most frequently lead to sepsis are the respiratory tract (39%–50%), urinary tract (5%–37%), and intra-abdominal space (8%–16%). Sepsis may be caused by gram-negative (50%–62% of sepsis) or gram-positive bacteria (37%–47%), as well as by fungi (5%) or other microorganisms.
Escherichia coli, Klebsiella species, and Pseudomonas aeruginosa are the most commonly isolated gram-negative pathogens in sepsis. Other common gram-negative pathogens are Serratia spp., Enterobacter spp., and Proteus spp. P. aeruginosa is the most frequent cause of sepsis fatality. Common gram-positive pathogens are Staphylococcus aureus, Streptococcus pneumoniae, coagulase-negative staphylococci, and Enterococcus species.
Candida species (particularly Candida albicans) are common fungal etiologic agents of bloodstream infections. The 30-day mortality rate for sepsis due to candidemia was 54%.
The pathophysiologic focus of gram-negative sepsis has been on the lipopolysaccharide (endotoxin) component of the gram-negative cell wall. Lipid A is a part of the endotoxin molecule from the gram-negative bacterial cell wall that is highly immunoreactive ...
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