2 learning resources available for this topic
Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, affecting over 1.7 million adults in the United States annually. Septic shock — characterized by vasoplegic circulatory failure and cellular metabolic abnormalities — carries mortality exceeding 40%.
The pathophysiology of sepsis involves microbial pattern recognition by innate immune receptors (TLRs, NLRs), triggering a massive cytokine release that disrupts endothelial integrity, activates coagulation, and impairs mitochondrial function. This produces microvascular dysfunction, distributive shock (decreased SVR with relatively preserved cardiac output), and ultimately multi-organ failure affecting the kidneys, liver, lungs, and brain.
Clinical reasoning uses the Sepsis-3 criteria: suspected infection plus a SOFA score increase ≥2. qSOFA (altered mentation, respiratory rate ≥22, SBP ≤100) is a bedside screen. Septic shock is diagnosed when vasopressors are needed to maintain MAP ≥65 despite adequate resuscitation. The 1-hour bundle includes blood cultures, broad-spectrum antibiotics, lactate measurement, and 30mL/kg crystalloid for hypotension or lactate ≥4. Source identification and control are paramount — differentials for septic shock include distributive causes (anaphylaxis, neurogenic) and non-distributive shock (cardiogenic, obstructive).
Common clinical reasoning questions about this topic
Sepsis-3 defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, identified by a SOFA score increase of 2 or more points. Septic shock is a subset with vasopressor requirement to maintain MAP ≥65 mmHg and lactate >2 mmol/L despite adequate resuscitation.
The surviving sepsis campaign 1-hour bundle includes: measuring lactate, obtaining blood cultures before antibiotics, administering broad-spectrum antibiotics, beginning 30mL/kg crystalloid for hypotension or lactate ≥4 mmol/L, and applying vasopressors if hypotension persists.
SIRS (systemic inflammatory response syndrome) can occur from non-infectious causes like pancreatitis or trauma. Sepsis requires a suspected or confirmed infectious source. Procalcitonin and lactate help differentiate, though clinical context is most important.